com,~iittee on chem'icals and explosives …~iittee on chem'icals and explosives ce-| ......

402 COM,~IITTEE O N C H E M ' I C A L S A N D E X P L O S I V E S C E - |

Report of Committee on

Chemicals and Explosives

Corre la t inR C o m m i t t e e

Dr. R o b e r t W. Van Dolah , Chairman, Pittsburgh Mining and Safety Research Center,

Bureau of Mines, U.8. Department of the Interior, 4800 Forbes Ave., Pittsburgh, PA 16213

C h e s t e r I. Babcock , t s ~ r v . National Fire protection Assn., 470 Atlantic Ave., Boston, MA 02210

W. 11. Doyle, Simsbury, CT H e n r y T. R i t t m a n , Insti tute of Makers o~ T h o m a s E. Duke , Fire Prevention & En- Explosives

g,neering Bureau of Texas R i c h a r d F. S c h w a b , Allied Chemical Corp, Dr. R i c h a r d Y. Le Vine, Olin Corp.

tNonvoting

Sec t iona l C o m m i t t e e o n C h e m i s t r y L a b o r a t o r i e s

Dr. R i c h a r d Y. Le Vine, Chairman, Olin Corp., 120 Long Ridge Rd., Stam/ord, CT 06904

C h e s t e r I. B a b o o . k , tSecretary, National Fire Protection Aesn. 470 Atlantic Ave., Boston, MA 02210

Dr. E r n e s t 1. Becker , American Chemical Society

L. H. Bradley , National Automatic Sprinkler. & Fire Control Assn., Inc.

H a r l a n R. Bra tvo ld , Underwriters' Labora- tories, Inc.

C h a r l e s E. B u r a p u s , McClellan AFB Fire Dept.

J . D. Coons , Factory Mutual Eagmeering Corp.

T r e n t o n Crow, U.8. Environmental Pro- tection Agency.

R. F. Fol tz , American Society of Safety Engineers

J a m e s E. F r e n c h , Scientific Apparatus Makers Aesa.

J o h n Frca ina , Campus Safety Association H o w a r d F. Kempse l l , American Petroleum

Institute IF. Owen Kublas , Glidden-Durkee, Die. of

SCM Corp. J o h n R. Leach , Omce of Administrative

Services, National Institutes of Health F. C. Loos, Fire Marshals Assn. of North

America H o r a c e Muhley , Woodbury, N . J .

tNonvoting

J o h n R o m l n e , R & D Section, Natienn} Safety Council

T h e o d o r u s R u y s , American Institute 01 Architects

R. F. Schwab , M~nufacturing Chemisl#' Assn.

Vic tor Se i t en . DHEW, Facilities Engineer. hag &.Construction

N o r m a n V. S teera , Minneapolis, Minn. R o b e r t J . W a h l , American Mutual in,

suranee Alliance J o h n H. W a r r e n , Paulsboro, N.J. Wi l l i am S. Wood, West Chester, Pa Alexander H. Z l m m e r m a o , BuildiM

Oflleials & Code Administrators Inter. national, Inv.

A l t e rna t e s .

M a r k Donde ro (Alternate to John Fresina) /

Pau l K. Hef ls tedt . (Alternate to Alexander H. Zimmerman)

George F. M u r p h y (Alternate to JChB Romine)

Kar l T. Spence , (Alternate to Trente0 �9 Crow)

i~K.2 S E C T I O N A L C O ~ M I T T E E S 403

Ser C o m m i t t e e o n Elec t r ica l E q u i p m e n t In C h e m i c a l A t m o 6 p h e r e s

Dr. R i c h a r d Y. Le Vine, Chairman. Olin Corp., 120 Long Ridge Rd., Stamford, CT 06904

C h e s t e r I. Babcock , tS~:retary, National Fire Protection Association, 470 Atlantic Ave., Boston, MA 02210

0 ~ J, llnll, Panel No. 14, N. E. Code Com- o l t ~

~ r t P. Howel l , American Petroleum titute

{ , ~ a O. Hunt, Jr., Manufacturing ~hcmtsts' A~e.

| / ton L. Lltehfleld, Safety Research Center. ~orvau of Mines, U.S. Department of the letsrlor pdmerlck L. M a l t b y , Instrument Society of

cries g. Miller, Factory Mutual Engineering

(~Orp. ~ T ~ k . E , R a d e m ~ c h e r , Factory Insurance

l,qOnvOtiOg

J o h n E. Ro~erson , Procter & Gamble Co. P. J . S c h r a m , Underwriters' Laborotories,

Inv. R. F. S c h w a b , Allied Chemical Corp. W. A. Sho r t , National Electrical Manu-

facturers Assn.

A/tefnAte8.

P. D. Al ro th (Alternate to P. J. Sehrsm) W. Ca lde r (Alternate to F. L. Maltby) W. H. Levers (Alternate to Roger P. Howell) J . R e n n l e (Alternate to C. L. Miller) T h o m a s S. S t a r o n (Alt~rnat~ to Freak E.

P.mdeme cher~

Sec t iona l C o m m i t t e e o n Explo61ves

H e n r y 3". R i t t m a n , Jr., Chairman, E. I. duPont de Nemours & Co., 12426 Nemours Bldg., Wilmin~,ton, DE 19898

(rep. Institute of Makers of Explosives)

C h e s t e r l . Bal~ock, t~qecr~ary. National Fire Prnteetion Association, 470 Atlantic Ave.. Boston. MA 02210

i ~ n n l d L. Bri#~s. Bureau of Alcohol, I'obnseo and Firearms. U.S. Dept. of the ' f r ~ s u r y

|)r . G l e n n H. D u m o n , Washington, DC ~, M. G r a z l a n o , Bureau of Explosives, As-

toeiatioo of American Railroads &, S. Hill , Sporting Arms and Ammunition

Manufacturers ' Institute ~ e | J o r d a n , Fire Marshals Assn. of North

America i[0acph McLa in , American Pyrotechnics

A~n. (floyd E. Oue l l e t t e , Manufacturing Chem-

t in ' ' A~sn. ~ t m u e l J . Por te r , Arlington, Va. ~dward C. Sab ln , Factory Insurance A~n. (}~lroll E. S h a w , New Haven, Conn.

Dr. Wi l l i am J . Tay lo r , Institute of Makers of Explosives

S t e p h e n C. U r m a n , Occupational Safety & Health Administration, Office of Standards

Dr. R o b e r t W. Van Dolah , Pittsburgh Min- ing & Safety Research Center, Bureau of Mines, U.S. Dept. of Interior

W. J . Welsh. Munitions Carriers Conference, lee,

AIterna tes. J a m e s E. Coll ier (Alternate to Edwald C.

Sabin A n t h o n y Fabr lz l (Alternate to Joseph

MeLain) C. W. Schu l t z (Alternate to R, M. Graziano) Te rence P. S m i t h (Alternate to Stephen C.

Urman)

INo~votin~

404 C O M M I T T E E O N C H E M I C A L S AND E X P L O S I V E S C E ~ I

Sec t iona l C o m m i t t e e o n Stara0te, I l a n d l l n g , a n d T r a n s p o r t a t i o n of I t a z a r d o u s C h e m i c a l s

WBI lam H. Doyle. Chairman, 36 Massacott, Simsbury, CT 06070

C h e s t e r i . Babcock , tSecretary, National Fire Protection Association, 470 Atlantic Ave., Boston, MA 02210

M. M. Ander son , : Manufacturing Chemists' Assn.

Caput. I l ewle t t R. Bishop, National Cargo ~ a , Inc.

Lt . Michae l T. B o h l m a n . U. S. Coast Guard

WIBlam Brndford,S Olin Corporation W. H. B u t t e r b a u ~ h , s Manufacturing Chem-

ists' Assn., Inc. J o h n A. Davenpo r t , Factory Insurance

Affisn. Ben F. Day,4 The Fertilizer Institute G e r a l d D u a r t e , Fire Marshals A~o. of

North America C. R. Eas tman ,8 American Petroleum In-

stitute L. P. H e r m a n , Rolf Jeusen & Associate~,

Inc. George H u c k e h a . American Mutual In-

surance Alliance H a r r y M c l n t y r e . e National Agricultural

Chemists Assn. S a m u e l J . Po r t e r , Arlington, Ca.

Ge ra ld P. S c h u l t z , t Society of the P l a l t ~ Industry

A r t h u r W. Sheldon,T Society of the Plmttb~ Industry

D a m o n W. S n o w , ' Monsanto Co. H e r m a n H. S p a e t h , lusuranee S e r v l ~

Office - - Pacific Region A r t h u r S p l e g e l m a n , American lasuran~

A~n. E u l a n G. T u c k e r , Toledo Fire Divlel0Q

Toledo, Ohio Dr. R o b e r t W. Van Dolah , P i t t sbut~

Mining & Safety Re~eareh Center, Bu~4~ of Min~

Al t e rna t e s .

J . P. Car ro l l (Alternate to A. W. Sheldon 6 G. P. Scliultz)

Cal~ct. D. W. G a t e s (Alternate to Cai~ wlett R. Bishop)

R. D. Mil ler (Alternate to Ben F. Day) R o b e r t W. Nelson (Alternate to John

Davenport) A n t h o n y San to s , Factory Mutual Engineer- C a p t . S. F. S a m m i s (Alternate to Qs~

ing Corp. Hewlett R. Bishop) C. W. S c h u l t z , Bureau of Explosive~ W . A . T l d r i d g e (Alternate to M. M. Andr0

Laboratory ~,m)

tNonvoting.

:Vote limited to NFPA 43A, 43B, 43C, 43D, 490 6Vote limited to NFPA 43D, 490

|Vote limited to NFPA 43A, 490 6Vote limited to NFPA 43A, 43D, 490

SVote limited to NFPA 43A, 43B TVote limited to NFPA 43B

Vote limited to NFPA 490 8Vote limited to NFPA 43A, 43B, 43(3, 4 ~

This list represents the membership at the time the Committee ume balloted on the text of this rdt l~ 8inse thai time, changes in the membership may have occurred.

EXPLANATION OF ItEpORT 405

The report of the Committee on Chemicals and Explosives is in ~ven parts:

Part I, prepared by the Sectional Committee on Explosives, #0poses adoption of amendments of the Code for the Manufacture, ftlnsportation, and Storage of Fireworks, NFPA No. 44A ~ 1973.

Part I, Ires been submitted for ballot to the Sectional Committee on Ex- #.,~lives, which consists of 75 voting members, of whom 13 have voted , ~'tmatively One member voted negatit~elr (R. M. Graziano), and I asked /'~ be recorded as not voting (S. Porter).

Part I has also been submitted for ballot to the Correlating Committee, ei~a'th consists of 6 voting members, of whom 6 have voted affirmatively.

Part II, prepared by the Sectional Committee on Chemistry 0e]boratories, proposes Tentative adoption of a Fire Protection qlandard for Laboratories Using Chemicals, NFPA No. 45-T.

Pari II has been submitted Jor ballot to the Sectional Committee on Chem- t',,~,l~ Laboratories, which consists of 24 voting members, of whom 22 have r~d~l affirmatively, and 2 Imve not voted (C. E. Bumpus, H. Mahley).

Part H has also been submitted to the Correlating Committee, which con- 'Oil of 6 voting members, of whom 6 have voted qffirmatively,

Part HI, prepared by the Sectional Committee on Storage, Handl- l~llh and Transportation of Hazardous Chemicals, proposes adoption t~'amendments of the Code for the Storage of Liquid and Solid (~)xldizing Materials, NFPA No. 4 3 A - 1973.

Part III has been submitted for ballot in two sections to the Sectional Com- e,tree on Storage, Handling, and Transportation of Hazardous Chemicals, r consists of 19 members entitled to vote on this Code. On Items 1-9,18 r162 affirmatively, and I did not return his ballot (D. Snow). On item lO, 04 uoted affirmatively, 2 negatively (W. Bradford, A. Spiegelman), 2 ~r recorded not voting (M. T. Bohlman, L. P. Herman), and I did not r162 his ballot (D. Snow).

Part III has also been submitted for ballot to the Correlating Committee, ~',~ith consists of 6 voting members of whom 6 have voted affirmatively.

Part IV, prepared by the Sectional Committee on Storage, |landling, and Transportation of Hazardous Chemicals, proposes 0'entative adoption of a Code for Storage of Pesticides in Portable r NFPA No. 4 3 D - P.

406 COMMITTEE ON CHEMICALS AND EXPLOSIVES C g

Part IV has been submitted for ballot to the Sectional Committo r Storage, Handling, and Transportation of Hazardous Chemicals, w~,~,: consists of 18 members entitled to vote on this Code, of whom 17 have t~;r affirmatively and 1 negatively ( A. Spiegelman).

Part IV has also been submitted for ballot to the Correlating Committt2 which consists of 6 voting members, of whom 6 have voted affrmativelv.

Part V, prepared by the Sectional Committee on Storage, Handl ing, and Transportation of Hazardous Chemicals, proposes "i'r tative adoption of a Code for the Storage of Gaseous Oxidizif~ Materials, NFPA No. 43C-P.

Part V has been submitted for letter ballot to the Sectional Committee r Storage, Handling, and Transportation of Hazardous Chemicals, whi~ consists of 16 members entitled to vote on this Code, of whom 1 1 have volta4 affirmatively, 4 negatively (07. A. Davenport, L. P. Herman, C. W. Schutl~, E. G. Tucker), and 1 has not returned a ballot (D. Snow).

Part V has also been submitted for ballot to the Correlating Committ~, which consists of 6 voting members of whom 6 have voted a~rmatioely.

Part VI, prepared by the Sectional Committee on Storage, HandD ing, and Transportation of Hazardous Chemicals, proposes Recoo firmation of the Standard for the Storage and Handling of Cellul~ Nitrate Motion Picture Film, NFPA No. 40 - - 1967.

Part VI has been submitted for ballot approval to the Sectional Co~ mittee on Storage, Handling, and Transportation of Hazardous Chemieol~ which consists of 14 members entitled to vote on tta's Standard, of whom IO have voted affirmatively.

Part VI has also been submitted for ballot to the Correlating Committo.j wta'ch consists of 6 voting members, of whom 6 have voted affirmatively.

Part VII, prepared by the Sectional Committee on Electrical Equipment in Chemical Atmospheres, proposes a complete revisi~ of the Standard for Purged and Pressurized Enclosures" for Electrir Equipment in Hazardous Locations, NFPA No. 496 - - 1972.

Part VII has been submitted for ballot approval to the Sectional Cor~ mittee on Electrical Equipment in Chemical Atmospheres, win'oh consists of I~ voting members, of whom 1/ have voted affirmatively and I asked to recorded as not voting (F. E. Rademather).

Part VII has also been submitted.for ballot to the Correlating Gommitter~ which consists of 6 voting members, of whom 6 have voted affirmatively.

REVISIONS TO NFPA NO. 44A 407

44A-1

Part I

Proposed Amendments of

Code for the Manufacture, Transportation, and Storage of Fireworks

N F P A No . 4 4 A ~ 1973

/~ Foreword, paragraph I, last sentence. Delete "and handling."

,~ Foreword, paragraph 2, first sentence, Delete "handling" and change ~)lher" to "most."

Foreword, paragraph 2, last sentencee. Change " than other explosive I. ~r to " than most explosive materials."

Foreword, paragraph 3, "first sentence. Change "if and when" to iN case of."

~ Foreword, paragraph 4, Revise to read: "Degree of confinement of P~eworks, whether by packaging, building walls or barricades, is of [~ramount importance. In contrast many Class A explosives will (,'~tonate when shock-initiated even if unconfined."

O, Foreword, paragraph 5. Delete "if and when an accident does ( {cur . "

~o Chapter 7, Section 11d. Change "shipment" to "manufacture" change "handling" to "storage."

PA Chapter l, Article 15. Revise definition of Bullet-Sensitive Explosives Material to read:

~ULLET-SENsITIVE EXPLOSIVES MATERIAL. Means any explosive rl~tterial that when tested at a density equal to that of the explosive (~l~tterial when packaged for shipment can be detonated by a 0~0-grain full metal case projectile (150-grain M2 ball ammunition) (]~:d from a standard .30-06 caliber rifle having a nominal muzzle ~clocity of 2,700 feet per second. The bullet is fired from a distance ~ 100 feet and the test material is at a temperature of 70 ~ to 75~ ~nd is immediately in front of a ~ inch - th i ck steel plate.

408 44A-2 C O M M I T T E E ON C H E M I C A L S A N D EXPLOSIYCES

9. Chapter I, Article 15. Delete definition of Explosive Material.

10. Chapter 2, Section 211c. Change "explosive materials" to " e x . . plosive and pyrotechnic compositions."

11. Chapter 2, Section 276, sentence 2. Change "conductive shoes" to "conductive shoes and cotton socks."

12. Chapter 3, Section 314a. Delete "and other explosive materials."

13. Chapter 5, Section 571. Add " H e shall be familiar with the traffic regulations, with applicable state and Federal regulations concern, ing fireworks, and with the provisions of this Code."

14. Chapter 6, Table I. Add .Note 6, to read: "All distances in Table I are to be applied with or without barricades or screen-type bard, cades."

LABORATORIES USING CHEMICALS 409 45-5

Part II

Proposed Tentative Standard on

Fire Protection for Laboratories Using Chemicals

N F P A N o . 4 S - T ~ 1974

Foreword

This Standard on fire protection for laboratories using chemicals ~ s prepared during 1969-1974 by the Sectional Committee on r Laboratories. The NFPA assembled and chartered this (t~ommittee at the prompting of school, industrial, research and ~0vernmental authorities who felt an urgent need for standard Iglddance in the fire protection of laboratories.

The Standard is divided into ten chapters of requirements. []xplanatory, advisory and reference material is in four appendices, which are not part of the Standard.

Appendix A contains explanatory material and recommended. Oltrl practices. Each Appendix A item is printed at the bottom of the page on which the requirement it relates to is printed. The ~zr good practices in Appendix A are those which the qk, nmittee feels are desirable supplements to the requirements in ~hc Standard. Appcndiccs B, C and D arc printcd at thc end of thc Standard.

Appendix B contains a method of calculating shock wavcs for cx- ~|osions; Appendix C contains rccommcndations for cquipmcnt t~pccdon, tcsting and maintcnancc; and Appcndix D is a list of (~gnNFPA publications rcfcrcnccd in thc Standard.

During the prcparation of thc Standard thc Committcc gathcrcd cxpcricncc. Thc cxpcricncc shows that automatic cxtinguishing

r and particularly sprinklcr systcms havc been cffccfivc in (;Ibfimizing laboratory losscs from fire. Noncombustiblc construc- (,'0tI has also been cEccdvc in limiting damagc. The cxpcricncc has ~o drawn attcnfion to thc nccd for I) bcttcr training of laboratory ~rsonncl and students in basic fire prcvcntion and conduct in fire ~'|,r 2) incrcascd attention to clcctrically safe systcms and c;luipmcnt; 3) safcr storage and handling of flammable liquids and (,,|~cs and other hazardous chcmicals, and 4) better maintcnancc ~d inspcction of laboratory cquipmcnt and vcnfilation systems. ~)vr managcmcnt commitmcnt to firc loss prcvcntion is csscntial 1|)crsons, propcrty and laboratory opcrations arc to bc propcrly ~feguardcd against firc and cxplosion hazards.

410 45-6 LABORATORIES USING CHEMICALS

Chapter 1 General

1-1 Purpose.

1-1.1 The standard prescribes basic requirements for the prO tection of life and property in laboratories where hazardous chela icals are handled, through prevention and control of fires and et~ plosions involving hazardous chemicals. The unique nature s many laboratory operations may make more stringent requiremenl~ necessary.

1-1.2 The standard is designed to protect persons from the effects of toxic, corrosive or otherwise hazardous chemicals to which they may be exposed as a result of a fire or explosion. Although il does not at tempt to deal with health hazards that are not related tO fires or explosions, many of the requirements to protect agaiml fires and explosions, e.g., those for hood exhaust systems, will aho serve to protect persons from exposure to nonfire health hazardt of chemicals.

I-1.3 The standard has the objective of achieving a compre, hensive laboratory fire protection program.

1-2 Scope,

1-2,1 This standard applies to laboratories in which hazardous chemicals are handled or stored.

Exception No. I. It does not apply to laboratories in buildings in which patient care is provided and that are covered by the Safety Standard for Laboratories in Health-Related Institutions, ArFPA No. 5 6 C - 7973.

Exception Aro. 2. It does not apply to pilot plants.

Exception .No. 3. It does not apply to laboratories that are in fact manu. facturing plants.

Exception .No. 4. It does not apply to incidental testingJacilitieiJor in-procesl control located within the manufacturing areas.

NOTE: For requirements for incidental testing facilities in industrial plants see Flammable and Combustible Liquids Code, NFPA No. 30 1973, Chapter V, Industrial Plants.

411 GENERAL 4 5 - 7

I-2.2 This standard contains requirements for conducting !h~atory experiments and for handling and storage of hazardous

r .No. 1. It does not cover the special fire protection required when '!~iag explosive materials.

~)TE: For requirements for storage of explosive material see the Code r Ihe Manufacture, Transportation, Storage and Use of Explosive ~qj|erials, NFPA No. 4 9 5 - 1973.

';r .No. 2. It does not cover the special fire protection required when :~Jling radioactive material.

~O'rE: See Recommended Fire Protection Practice for Facilities Handling r Materials, NFPA No. 801 ~ 1970.

/ r .No. 3. It does not contain all-inclusive requireraentsfor conducting ~,~r experiments.

1.3 Definitions. The following terms, for the purpose of this 0,tdard, will have the meanings indicated below.

~0mbustible Liquid. See Flammable and Combustible Liquids.

~lucat ional Occupancies. Buildings used for the gathering of .~ or more persons for purposes of instruction, such as schools, ~ ~[versities, colleges, and academies.

t~tplosive Material . A chemical compound, mixture or device, 1'~2 primary or common purpose of which is to function by explosion.

R O T E : For a more detailed definition of explosive material see Code for |h~ Manufacture , Transporta t ion, Storage and Use of Explosive M a - qcrluls, N F P A No. 495 - - ! 973.

Flammable Gas. A gas that will burn in the normal coneen- (O0tion of oxygen in air.

Flammable and Combustible Liquids. A liquid having a flash ~3]nt below 100*F (37.80C) and having a vapor pressure not ;~ceeding 40 pounds per square inch (absolute) at 100~ (37.8~ I~il be known as a Class I liquid.

Class I liquids shall be subdivided as follows:

Class 1A shall include those having flash points below 73~ !~]2,8*C) and having a boiling point below 100~ (37.80C).

Class IB shall include those having flash points below 73~ ~2.8~ and having a boiling point at or above 100*F (37.8"12).

Class I(2 shall include those having flash points at or above t3*F (22.8*(2) and below 100*F (37.8*0).


COMBUSTIBLE Liqum. A liquid having a flash point at or a b ~ 100~ (37.8~

COMSUSTIBLE LIQUIDS shall be subdivided as follows:

Class I I liquids shall include those .having flash points at ~ above 100~ (37.8~ and below 140~ (60~

Class I I I A Liquids shall include those having flash points 0~ or above 140~ (60~ and below 200~ (93.4~

Class I I IB Liquids shall include those having flash points a~ or above 200~ (93.4~

Flash Point. The minimum temperature at which a liquid givo off vapor in sufficient concentration to form an ignitible mixtucr with the vessel as specified by appropriate test procedure and ap, paratus.

NOTE: The flash point of a liquid having a viscosity less than 45 SUS at 100~ (37.8~ and a flash point below 200~ (93.4~ shall be determined in accordance with the Standard Method of Test for Flash Point by the Tag Closed Tester, ASTM D 56--70. (See reference D1 in Appendix D.)

The flash point of a liquid having a viscosity of 45 SUS or more at 100~ (37.8~ or a flash point of 200~ (93.4~ or higher shall be determined in accordance with the Standard Method of Test for Flash Point by the Pensky-Martens Closed Tester, ASTM D 93--72. (See reference D15 in Appendix D.)

Hazardous Chemical. A chemical with one or more of the follow. ing. hazard ratings as defined in Recommended System for the Ident~, catwn of the Fire Hazards of Materials, ArFPA No. 704M--1969: Health 2, 3 or 4 ; Flammability, 2, 3 or 4; Reactivity, 2, 3 or 4.

NOTE: For hazard ratings of many chemicals see Hazardous Chemicals Data, NFPA No. 49 - - 1973 and Fire Hazard Properties of Flammable Liquids, Gases, and Volatile Solids, NFPA No. 325M - - 1969.

Health 4. Materials which on very short exposure could cause death or major residual injury even though prompt medical treat. ment were given, including those which are too dangerous to be approached without specialized protective equipment. This degree should include:

Materials which can penetrate ordinary rubber protective clothing;

Materials which under normal' conditions or under fire conditions give off gases which are extremely tiazardous (i.e., toxic or corrosive) through inhalation or through contact with or absorption through the skin.

Health 3. Materials which on short exposure could cause serious temporary or residual injury even though prompt medical treatment

413 GENERAL 4 S - 9

,:;rC given, including those requiring protection from all bodily ~, ~lact. This degree should include:

Materials giving off highly toxic combustion products;

Materials corrosive to living tissue or toxic by skin absorption.

I lealth 2. Materials which on intense or continued exposure ~,~dd cause temporary incapacitation or possible residual injury L ;dess prompt medical treatment is given, including-those requiring I ~ of respiratory protective equipment with independent air supply. t/his degree should include:

Materials giving off basic toxic combustion products;

Materials giving off highly irritating combustion products;

Materials which either under normal conditions or under fire ~0nditions give off toxic vapors lacking warning properties.

Flammability 4. Materials which will rapidly or completely ~porize at atmospheric pressure and normal ambient tempera- lore or which are readily dispersed in air, and which will burn ~adily. This degree should include:

Gases;

Cryogenic materials;

Any liquid or gaseous material which is a liquid while under pressure and having a flash point below 73~ (22.8~ and having a boiling point below 100~ (37.8~ (Class IA flammable liquids.)

Materials which on account of their physical form or environmental conditions can form explosive mixtures with air and which are readily dispersed in air, such as dusts of combustible solids and mists of flammable or combustible liquid droplets.

Flammability 3. Liquids and solids that can be ignited under almost all ambient temperature conditions. Materials in this degree produce hazardous atmospheres with air under almost all ambient temperatures or, though unaffected by ambient temperatures, are r ignited under almost all conditions. This degree should Include:

Liquids having a flash point below 73~ (22.8~ and having a boiling point at or above 100~ (37.8~ and those liquids having a flash point at or above 73~ (22.8~ and below 100~ (37.8~

Solid materials in the form of coarse dusts which may burn rapidly but which generally do not form explosive atmospheres with air;


Solid materials in a fibrous or shredded form which may b~l~,J, rapidly and create flash fire hazards, such as cotton, sisal and hetl~-

Materials which burn with extreme rapidity, usually, by reo~,~, of self-contained oxygen (e.g., dry nitrocellulose and many orgar~ peroxides) ;

Materials which ignite spontaneously when exposed to air.

Flammability 2. Materials that must be moderately heated (4 exposed to relatively high ambient temperatures before igniti~ can occur. Materials in this degree would not under normal e01~, ditions form hazardous atmospheres with air, but under high ambient temperatures or under moderate heating may release v a l ~ in sufficient quantities to produce hazardous atmospheres with ah' This degree should include:

Liquids having a flash point above 100 ~ F (37.8~ hut not exceeding 200~ (93.4~ ;

Solids and semisolids which readily give off flammable vapors,

Reactivity 4. Materials which in themselves are readily capable of detonation or of explosive decomposition or explosive reaction at normal temperatures and pressures. This degree should include materials which are sensitive to mechanical or localized thermal shock at normal temperatures and pressures.

Reactivity 3. Materials which in themselves are capable of detonation or of explosive decomposition or explosive reaction but which require a strong initiating source or which must be heated under confinement before initiation. This degree should include materials which are sensitive to thermal or mechanical shock at elevated temperatures and pressures or which react explosively with water without requiring heat or confinement.

Reactivity 2. Materials which in themselves are normally unstable and readily undergo violent chemical change but do not detonate. This degree should include materials which can undergo chemical change with rapid release of energy at normal temperatures and pressures or which can undergo violent chemical change at elevated temperatures and pressures. It should also include those materials which may react violendy with water or which may form potentially explosive mixtures with water.

Instructional Labora tory Unit. A laboratory unit in an educational occupancy in which the person or persons conducting chemical experiments or tests are under the direct supervision of a faculty member or his assistant.

GENERAL 415 45-11

l abora to ry . A facility for testing, analysis, research, instruction ~' similar activities which involves the use of chemical materials.

l abo ra to ry Building. A structure used wholly or primarily for 0aboratory use or in which 50 percent or more of the total floor area f~mtains laboratory units.

Laboratory Apparatus. Furniture, laboratory hoods, centrifuges, refrigerators, and commercial or made-on-site apparatus used in a laboratory.

Laboratory Equipment . See Laboratory Apparatus.

Laboratory Unit. An enclosed space used for experiments or tests. Laboratory units may include ollices, lavatories and other contiguous rooms maintained for or used by laboratory personnel and include corridors within the units.

NOTE: See Chapter 3, Laboratory Construction and Dcaign, for requirements for enclosure of laboratory units.

Class A Laboratory Unit. A laboratory unit in which the quantities of flammable or flammable and combustible liquids exceed those for a Class B laboratory unit as shown in Table 2-1 but do not exceed those shown for a Class A laboratory unit.

Class B Laboratory Unit. A laboratory unit in which the quantities of flammable or flammable and combustible liquids exceed those for a Class C laboratory unit as shown in Table 2-1 but do not exceed those shown for a Class B laboratory unit.

Class C Laboratory Unit. A laboratory unit in which the quantities of flammable or flammable and combustible liquids do not exceed those shown for a Class C laboratory unit as shown in Table 2-1.

Labora tory Unit Separation. All walls, partitions, floors and ceilings, including openings in them, between a laboratory unit and adjoining areas in the building.

Nonlaboratory Area. A space used for purposes not related direcdy to chemical experiments or tests (see definition o~ Laboratory Uni t ) .

Potential ly Explosive Reaction. Any chemical procedure that uses or forms reactive materials.

Reactive Material. A material that by itself is readily capable of detonation or of explosive decomposition or explosive reaction at normal or elevated temperatures and pressures. (See also in definition Of Hazardous Material the definitions of Reactivity 3 and Reactivity 4.)


Safety Can. An approved container, of not more than five galloJt~ capacity, having a spring-closing lid and spout cover and so designed that it will safely relieve internal pressure when subjected to fi~ exposure.

Storage Cabinet. A cabinet for the storage of flammable anti combustible liquids that is constructed in accordance with the re. quirements for storage cabinets for flammable and combustible liquids in the Flammable and Combustible Liquids Code, NFPA No. 30 1973.

Storage Room. A room for the storage of flammable and combustible liquids that is cut off from surrounding areas and constructed and ventilated in accordance with the requirements for inside storage rooms for flammable and combustible liquids in the Flammable and Combustible Liquids Code, .NFPA No. 30 ~ 1973.

Story. That portion of a building included between the upper surface of a floor and the upper surface of the floor or roof next above.

Unattended Laboratory Operation. No person present who is knowledgeable regarding the operation and emergency shutdown procedures.

1.-4 Interface with existing standards and codes. 1-4.1 Where areas of interface with existing NFPA and other

consensus standards and codes occur, reference is made to the ap- �9 propriate source in the text.

1-4.2 Where necessary, due to the special nature of laboratories, existing standards and codes are supplemented in this text so as to apply more specifically to buildings or portions of buildings de- voted to laboratory usage.

1-4.3 Where a construction or protection requirement o! a governmental agency having jurisdiction is more stringent than that in this standard, the more stringent requirement shall apply.

417 LABORATORY HAZARD CLASSIFICATION 45--13

Chapter 2 Laboratory Hazard Classification

~1 General.

This c h a p t e r classifies l abora to r ies on the basis of the a m o u n t of 0~, , t tnable and combus t ib l e l iquids present and defines w h e n an 6, ~)losion h a z a r d exists. T h e a p p r o p r i a t e p ro tec t ion for fire h a z a r d ~it found in C h a p t e r 4 and for s ignif icant explos ion haza rd in C h a p t e r %

2-1.1 Fire H a z a r d Classif icat ion.

2-1.1 .1" L a b o r a t o r y units shall be classified as Class A, B or q~ ~lccording to the quan t i t i e s specif ied in T a b l e 2-1.

A p p e n d i x A

Appendix A, which starts here and continues at the Jeet of other pages of the ~iandard as necessary, is not a part of the Standard and is included for eq[ormation purposes only.

*A2-1.1.1 Six conditions can affect the classification of a laboratory unit: 1, Iho quantity of Class I liquids per unit area; 2, the combined quantities of Classes |, I / a n d I l IA liquids per unit area; 3, the area of the laboratory unit; 4, the quantity of Class l liquids in safety cans and storage cabinets; 5, the combined qunndues of Classes I, II and IIIA liquids in safety cans and storage cabinets; mid 6, the presence of automatic sprinkler protection or other approved automatic fire extinguishing system.

Example 1. A 5000 square foot unsprinldered laboratory unit containing ?5 gallons of Class I liquids, 125 gallons of Clam II liquids, and 75 gallons of Class I I IA liquids (excluding quantities in storage cabinets and safety cans). This is a Class A laboratory unit. Reason: Although neither the quantity of Class I liquids per 100 square feet (2.5 gallons) nor the combined quantity of Class I, II and I l IA liquids per 100 square feet (5.5 gallons) exceeds the quantities per 100 square feet permitted for a Class B laboratory (5 and 10 gallons respectively) the total 9uantity of Classes I, II and I l IA liquids (275 gallons) exceeds that permitted m an unsprinklered Class B laboratory unit (200 gallons) but does not exceed that permitted in a Class A unit (400 gallons).

Example 2. The same laboratory unit as in Example 1 except that it is protected by sprinklers. This is a Class B laboratory unit. Reason: The total quantity of Classes 1, II and IIIA liquids (275 gallons) exceeds that permitted Jn a sprinklered Class C laboratory unit (200 gallons) but does not exceed that permitted in a sprinklered Class B unit (400 gallons).

Example 3. The same laboratory unit as in Example 2 but with an additional 200 gallons of Class I, 400 gallons of Class II and 300 gallons of Class I l iA liquids in storage cabinets and safety cans. This is a Class A laboratory unit. Reason : The total quantity of liquids (1175 gallons) exceeds that permitted in a sprinklered Class B laboratory unit (800 gallons) but does not exceed that permitted in a Class A unit (1600 gallons).

Example 4 . .An unsprinklered 1000 square foot laboratory unit containing the same quantities of liquids as in Example 1. A 1000 square foot laboratory unit with those quantities is not permitted. Reason: The combined quantity per 100 square feet 6f Classes I, II and I l i a liquids (27.5 gallons) exceeds that permitted in a Class A laboratory unit (20 gallons).

T a b l e 2-1. M a x i m u m Q . u a n t i t i e s o f F l a m m a b l e a n d C o m b u s t i b l e L i q u i d s i n L a b o r a t o r y U n i t s ' Outsade of Approved Flammable Liquid Storage Rooms

Flammable Laboratory or

Unit Combustible Class Liquid Class

Excluding Quantities in Storage Cabinets and Safety Cans

Maximum Quanti ty s

Per 100 Square Feet of .Maximum Allowable

Laboratory Quanti ty 8 Per Uni t . Laboratory Unit

Including Quantities in Storage Cabinets and Safety Cans

Maximum Quanti ty 2

Per 100 Square Feet of Maximum Allowable

Laboratory Quanti ty s Per Unit Laboratory Unit

UnspHnklered Sprinklered 5 Unsprinklered Sprinklered 6

A I 10 Gallons 300 Gallons 600 Gallons 20 Gallons 600 Gallons 1200 Gallons I, l I and IliA+ 20 Gallons 400 Gallons 800 Gallons 40 Gallons 800 Gallons 1600 Gallons

B I 5 Gallons 150 Gallons 300 Gallons 10 Gallons 300 Gallons 600 Gallons I, II and I l iA + 10 Gallons 200 Gallons 400 Gallons 20 Gallons 400 Gallons 800 Gallons

C I 2 Gallons 75 Gallons 150 Gallons 4 Gallons 150 Gallons 300 Gallons I, II and I l i A 4 4 Gallons 100 Gallons 200 Gallons 8 Gallons 200 Gallons 400 Gallons

t Class A Laboratory Units shall not be used as instructional laboratory units and the maximum quantities of flammable and combustible liquids in Class B and Class C Instructional Laboratory Units shall be 50% of those in Table 2-1.

-~ For maximum container sizes see Table 7-1.

, R ~ of th.~ magi." .mum aUow~.le q ~ , i t y , the max. tun anamtnt m a ~ t m ' y un,t shall ne~aer exceed

that calculated by using the maximum quantity per 100 square feet�9

+ The maximum quantities of Class I liquids shall not exceed the quantities specified for Class I liquids alone.

6 In laboratory units where water creates a serious fire or personnel hazard, a nonwater extinguishing system may be substituted for sprinlde~.

419 LABORATORY HAZARD CLASSIFICATION 45-15

2-1.1.2 Class A l abora to ry units shall not be used as in- q;o~telional l abo ra to ry units and the m a x i m u m quant i t ies of f lam-

>:;hie and combust ib le l iquids in Class B and Class C instruct ional I~*bratory units shall be 50 percent of that in T a b l e 2-1.

2-1.1.3 M a x i m u m capac i ty of conta iners in l abora to ry writs g~gdl co ,nply wi th T a b l e 7-1 and p a r a g r a p h 7-2.3.4.

2-1.1.4 Requ i remeuts for l abora to ry units in this s t anda rd {'.~3U apply to all l abora to ry units unless identif ied as app ly ing to a ?~l~watory unit of a specific haza rd class.

2-1.2 Exp los ion H a z a r d Class i f ica t ion.

2-1.2.1" A l abora to ry unit shall be considered to conta in an ,~plnsion hazard if any of the react ions descr ibed in (b) th rough (e) Ieb)w are present or any of the mater ia ls descr ibed in (a), (b) and ~} below are present in such quant i t ies and concent ra t ions tha t ,'.~Jor s t ructura l d a m a g e could result from an explosion. ~O'I'E: Explosions that will not cause major structural damage in a labora- lucy unit may injure or kill a person in the immediate vicinity of the blast.

(tO The s torage of mater ia ls with a react iv i ty of 4.

0)) T h e use or format ion of mater ia ls wi th a react iv i ty of 3 or 4.

~q') Highly exothermic react ions e.g., polymerizat ions , oxidat ions, ~leations, Fr iedel-Craf ts , Gr igna rds and cer ta in o ther o rgano- :~lallics.

((I) T h e use or format ion of mater ia ls whose structures indica te a (,),~lential haza rd but whose proper t ies have not been establ ished r Iriple bonds, epoxy radicals , ni tro and nitroso compounds and (,r

(e)* High pressure reactions.

~ O'['E: For reactivity ratings of many chemicals see Hazardous Chemicals ata, NFPA No. 49--1973 and Fire Hazard Properties of Flammable

|]qu|ds, Gases, and Volatile Solids, NFPA No. 3 2 5 M - 1969.

4ppendlx A (continued) A2-1.2.1 An explosion overpressure of 6 psi is sufficient to shatter an un-

r concrete or cinder-block wall 8 in. to 12 in. thick, shatter transi~e or

~W um board, buckle steel or aluminum paneling or buckle 2 in. by 6 in. wood cJ~,m. A formula and graph for estimating the peak reflected pressure is in-

~!~:~tl In Appendix B. The source is "Structures to Resist the Effects of Acci- c'!:;~l~l I~xplosions," (See reference D2 in Appendix D. )

A2-1.2.1e Items a through h below contain recommendations for classifying r162 in vessels.as high pressure and low pressure and contain recom-

"~.~l(Itttions for protecting against explosion hazards of reactions conducted at * t ? ~ atmospheric pressures.

0~ Reactions below the curve in Figure A2-1.2.1e should be classified as low ~ '~Brc reactions.


Appendix

1000

500 "~ 4 0 0

3oo

: 200

r moo b~ ,, 8 0

60

0 40 ~ 30

A (continued)

,, HI-PRESSURE REACTIOn, S

LOW

I ATMOSPHERE

I0 t I 0.01 0.1 I 4

Volume of Reactor (Liters)

Figure A2-1.2.1.e

b. Reactions above the curve ill Figure A2-1.2.1eshould be classified as high pressure reactions.

c. High pressure experimental reactions should be conducted behind sub. stantial fixed barricades able to withstand lateral forces of at least 1 psi static loading without fragmenting. The barricades should be firmly supported at the top and bottom to take those loads. At least one wall shou ldbe explosim~ venting (See Chapter 5 and see the Guide for Explosion Venting, NFPA No. 68 1074.)

d. Experimental reactions that are known to involve materials inherently unstable, such as reactions with acetylenic compounds and certain oxidatio~ such as halogenations and nitrations, should be barricaded even if, because 0~ the pressures and volumes, they fall below the curve in Figure A2-1.2.1e. (So Items a, b and r under 2-1.2.1.)

e. Routine reactions where pressures and temp.eratures are expected between certain predetermined limits based on long expezaence or routine work need n01 be conducted behind barricades if the vessels comply with items f and g below,

f. Vessels should be built of suitable materials of constxuction and ha~,e a~ adequate safety factor.

[~..Ml vessels should be provided with pressure relief in the form of a safet) rehef valve or a rupture disc. (See 9-2.6.)

h. Low pressure reactions, if it is deemed necessary to do so, should be con ducted in hoods or behind portable barricades.

LABORATORY CONSTRUCTION AND DESIGN 421 45-17

Chapter 3 Laboratory Construction and Defign

~-1" Labora tory Unit Enclosure.

3.1.1 The required construction of laboratory units depends '} the hazard classification, the area and the protection to be pro-

3.1.2 The construction requirements are the minimum per- filed and do not exclude the use of construction with greater fire

, ,~flstance.

3-1.2.1 Laboratory units shall be separated from non- I'~boratory spaces by construction equal to or greater than the fire- ,zllstance requirements shown in Table 3-1.

3-1.2.2 Laboratory units shall be separated from other I'd)oratory units of equal or lesser hazard class by construction meet- I QI or exceeding the fire-resistance requirerdents shown in Table 3-1.

3-1.2.3 Laboratory units shall be separated from other I~lboratory units of a higher hazard class by construction meeting or r162 the separation requirements for the higher hazard class 4h0wn in Table 3-1.

3.2 Maximum Area of Labora tory Units.

3-2.1 The maximum area of a laboratory unit shall be deter- ~ulned by the fire hazard classification, the construction of the build- 10g and the fire protection provided as shown in Table 3-1.

3-3 Means of Egress Requirements.

3-3.1 Means of Egress in Laboratory Buildings.

3-3.1.1 Means of egress requirements for a laboratory building shall comply with the exit requirements specified for the oc- fttpancy of the building in the Code for Safety to Life from Fire in Buildings and Structures, ~fFPA No. 101 ~ 1973. Laboratory buildings shall comply with the exit requirements for general purpose Industrial buildings except that such buildings as educational in- tlhutions shall comply with the exit requirements for educational occupancies.

Appendix A (continued) A3-! Consideration should be given to providing proper drainage for

Ilammable liquids and water used for fire extinguishment:

T a b l e 3-1. C o n s t r u c t i o n a n d F i r e P r o t e c t i o n R e q u i r e m e n t s f o r L a b o r a t o r y U n i t #

Labora- tory Uni t Class

Nonspr lnHered Labora tory Units Sprinldered Labora tory Units :

In Fire-resistive, Protected In Heavy Timber, Ordinary Any Building or Laboratory Noncombustible or Non- or Wood Frame Buildings Construction

combustible Buildings Separation from Separation from Separation from

Separation Laboratory Units Separation Laboratory Units Separation Laboratory Units Area of from Non- of Equal . from Non- of Equal from Non- of Equal

Laboratory laboratory or Lower laboratory or Lower laboratory or Lower Unit Units a Hazard Class a Units a Hazard Class a Units ~ Hazard Class s

Under 1000Sq. Ft. 1 Hour I Hour 2 Hours I Hour I Hour 1000-2000 Sq. Ft. 1 Hour 1 Hour Not Permitted 1 Hour 2001-5000 Sq. Ft. 2 Hour I Hour Not Permitted I Hour 5001-10,000 Sq. Ft. Not Permitted Not Permitted 1 Hour 10,000 or more

Sq. Ft. Not Permitted Not Permitted

Noncombustible' Noncombustible t Noncombustible'

1 Hour

Not Permitted

Under 20,000 Sq. Ft.

20,000 or more Sq. Ft.

1 Hour Noncombustible ~ 1 Hour 1 Hour

Not Permitted Not Permitted

Non- comb.' . ~ Noncombustible ~

Not Permitted

C Under 10,000 Sq. 1 Hour Noncombustible' 1 Hour

Ft. 10,000 or more 1 Hour Noncombustible' 1 Hour

Sq. Ft.

Noncombustible ~ Non- comb. ~. s No Requirement

1 Hour Non- comb. ' , j Noncombustible'

t Where a laboratory unit contains an explosion hazard, appropriate explosion protection shall be provided for adjoining laboratory units and nonlaboratory areas as specified in Chapter 5.

s In laboratory units where water creates a serious fire or personnel hazard, a n'onwatcr extinguishing system may Ix substituted far aininHetz.

including the resistance of wall, partition, floor and ceiling construction see "Fire Protection Handbook," Boston, NFPA, 1969, Thirteenth Edition, pages 8-86 ~.8-124. May be ~ - h o u r rated combustible construction in lieu of noncombustible construction separation.

s In educhtionaJ ~ c u ~ c s lal:x~'atm'y un iu shaft be

423 LABORATORY CONSTRUCTION AND DESIGN 4~--1~

3-3.2. Exit Access From Laboratory Units.

3-3.2.1 A second means of access to an exit shall be provided rh~*|~ a laboratory unit if any of the following conditions exist:

(a) A laboratory hood in a Class A or Class B laboratory ~ h is located adjacent to the door.

(b) The laboratory unit is a Class A unit and exceeds 500 r feet.

(c) The laboratory unit is a Class B or Class C unit and 6~eeds 1,000 square feet.

3-3.2.2 The main door of all laboratory units shall swing in ~he direction of egress.

3-3.3 Furn i tu re and Equipment.

3-3.3.1 Furniture and laboratory equipment in laboratory it,dis shall be arranged such that means of access to an exit may be Cfnched easily from any point.

3-3.4 Electrical Systems.

3-3.4.1 All electrical installations including wiring and ap- [}~trtenanees, apparatus, lighting, signal systems, alarm systems, fclnote control installations, commumcauon systems and emer- ~r power systems or parts thereof, shall be in conformance with the provisions of the .National Electrical Code, .AfFPA No. 7 0 - 1971.

3-3.4.2 Laboratories shall be considered as unclassified electrically, with respect to the JVational Electrical Code, JVFPA .No. 7 0 - - 1971, Article 500.

I~t'ception. Under some conditions of extraordinary hazard, it may be r to classify a laboratory or a part thereof as a hazardous location, for tb~ purpose of designating suitable electrical installations.

NOTE: For examples, see 9-2.3.1 and 9-2.5.1

424 45 -20 LABORATORIES USING CHEMICALS

Chapter 4 Fire Protection

4-1 Genera/.

4-1.1 All laboratory units shall have fire protection appropriate to the fire hazard as follows:

(a) Portable fire extinguishers (see Article 4-4). (b) An alarm system (see Article 4-5). (c) An evacuation and emergency plan (see Article 4-6).

4-1.2 In addition to the fire protection specified in 4-1.1, laboratory units under some conditions shall be provided with (a) automatic extinguishing systems (see Article 4-2), and (b) inside stand-pipe and hose systems (see Article 4-3).

4-2 Automatic Fire Ext inguishing Systems.

4-2.1" Genera/.

4.2.1.1 An automatic fire extinguishing system may be required in a laboratory unit, depending upon the construction of the building, the hazard class of the laboratory unit, the cofistruction of its enclosure, and its area. Table 3-1 in Chapter 3, which shows the interrelationship of hazard class, automatic protection, construction, and area, shall be followed.

4-2.2 Automatic Spr inkler Systems.

4-2.2.1 Automatic sprinklers for Class A laboratory units shall be designed for extra hazard occupancies or shall be hydraulic- ally calculated for Ordinary Hazard Group 3, as specified in the. Standard for the Installation of Sprinkler Systems, ~fFPA No. 7 3 - - 1973.

42.2.2 Automatic sprinklers for Class B laboratory units. shah be designed for ordinary hazard occupancies or shah be hy- draulically calculated for Ordinary Hazard Group 2, as specified in the Standard for the Installation of Sprinkl~ Systems, ArFPA .No. 1 3 - 1973.

Appendix A (continued)

A4-2.1 The automatic fire extinguishing system should be an automatic spr/nkler system. If extinguishment or control may be more effectively ac- compl/sbed by a type of automatic extingu/shing system that does not use water, it may be advisable to install another type of extinguishing system in lieu of sprinklers.

425 FIRE PROTECTION 45-21

4-2.2.3 Automatic sprinklers for Class C laboratory units shall be designed for ordinary hazard occupancies or shall be hy- draulically calculated for Ordinary Hazard Group 1, as specified in the Standard for the Installation of Sprinkler Systems, NFPA .No. 1 3 - 1973.

4-2.2.4 Automatic sprinkler systems shall be inspected regularly, cared for properly and maintained in service.

NOTE: See Recommended Practice for the Care and Maintenance of Sprinkler Systems, NFPA No. 13A - - 1971.

4-2.3 Other Automatic Extinguishing Systems. 4-2.3.1 Nonwater automatic extinguishing systems or special

hazard extinguishing systems when required, shall be designed, installed and maintained in accordance with the appropriate standards:

(a) Standard on Carbon Dioxide Extinguishing Systems, NFPA No. 12 - - 1973.

(b) Standard on Halogenated Fire Extinguishing Agent S y s t e m s - - H a l o n 1301, NFPA No. 1 2 A - - 1 9 7 3 .

(c) Standard on Halogenated Fire Extinguishing Agent S y s t e m s - - Halon 1211, NFPA No. 12B - - 1973.

(d) Standard for Dry Chemical Extinguishing Systems, NFPA No. 17 - - 1973.

(e) Standard for Foam Extinguishing Systems, NFPA No. 11 - - 1973.

(f) Standard for High Expansion Foam Systems, NFPA No. l l A - - 1970.

(g) Standard for Water Spray Fixed Systems for Fire Protection, NFPA No. 15 - - 1973.

(h) Standard on Explosion Prevention Systems, NFPA No. 69 - - 1973.

4-2.4 The discharge of an automatic fire extinguishing system shall activate an alarm system.

4-3 Standpipe and Hose Systems. 4-3.1" In all buildings with two or more stories above or below

ground level 1 - ~ inch hose connections with hose and combination straight stream and fog nozzle shall be provided for use by occupants.

NOTE: Ground level is meant to be the lowest point of accessibility for building entrance by the fire brigade or fire department.

Appendix A (continued) A4--3,1 Waterflow from the standpipe system should activate a fire alarm.


4-3.2 In all unsprinklered buildings with two or more storicj above or below ground level a standpipe with 2-1,,~ inch hose con, nections shall be provided for use by the fire brigade or fire deparl, ment.

4-3.3 Standpipes shall be installed in conformance with the requirements in the Standard for the Installation of Standpipe and Hose Systems, NFPA No. 1 4 - 1973.

4-3.4 Hose shall be of an approved type and shall be tested an0 cared for in accordance with the Standard for Care of Fire Hose, NFPA No. 198 - - 1972.

4-3.5 Standpipes and hose systemsshall be inspected and main. rained in accordance with the Standard for the Installation of Stand. pipe and Hose Systems, jVFPA .No. 1 4 - - 1973.

4-4 Por table Fire Extinguishers.

4-4.1 Portable fire extinguishers shall be installed and located in accordance with the Standard for the Installation of Portable Fire Extinguishers, JVFPA .No. 10 - - 1973. Class A laboratory units shall be graded as extra hazard, and Class B and C laboratory units as ordinary hazard.

4-5 Alarm Systems.

4-5.1 A manual fire alarm system shall be installed in a laboratory building if a fire may not of itself provide adequate warning to building occupants.

4-5.2 Fire alarm systems and fire detection systems, where required, shall be installed and maintained in accordance with one of the following:

(a) Standard for the Installation, Maintenance and Use of Local Protective Signaling Systems for Watchman, Fire Alarm and Supervisory Service, NFPA No. 7 2 A - 1972.

(b) Standard for the Installation, Maintenance and Use of Auxiliary Protective Signaling Systems for Fire Alarm Service, NFPA No. 7 2 B - 1972. "

(c) Standard for the Installation, Maintenance and Use of Remote Station Protective Signaling Systems, NFPA No. 72C - - 1972.

(d) Standard for the Installation, Maintenance and Use of Proprietary Protective Signaling Systems for Watchman, Fire Alarm and Supervisory Service, NFPA No. 72D 1973.

427 FIRE PROTECTION 45-23

4-5.2.1 Signal transmission for a larms designed to activate ~]gnals at more than one location shall be verified at each location during each inspection of the a la rm system.

4-5.3 The fire a la rm system, where required, shall be so de- dgned that all personnel endangered by the fire condi t ion or a contingent condi t ion will be alerted.

4-5.4 The fire a la rm system shall alert a local fire brigade or public fire depa r tmen t to a fire.

4-6 Fire Loss Prevention.

4-6.1 Emergency Procedures.

4-6.1.1" Procedures for laboratory emergencies shall be de- veloped. Such procedures shall include a la rm actuat ion, evacuat ion and equ ipment shutdown procedures, and provisions for fire-fighting action inc luding specific detailed plans for fire control operations by an emergency control organizat ion or a public fire depar tment .

NOTE: For additional information on fire loss prevention organization, see Recommendations for Organizations of Industrial Loss Prevention, NFPA No. 6 - - 1967.

4 6 . 2 F i r e Prevention Procedures.

4-6.2.1 Fire prevent ion procedures shall be established. The following critical areas require special considerat ions: hand l ing and storage of f lammable combust ible l iquids; hand l ing and storage of hazardous materials; open flame and spark-producing work permit system; a r rangement and use of portable electric cords; and smoking area controls.

Appendix A (continued) A4-4LI.1 Emergency telephones are of value when they are connected

direcdy to an emergency office and when they are located within the laboratory building so that they can be readily used by laboratory personnel and also when they are available at an exterior location for use by evacuees or passersby. An emergency telephone system should be inter-connected with a mass noti- fication system such as a public address system.

a. Evacuation procedures. The management of each laboratory or laboratory building covered by this standard should be responsible for promulgating and distributing an appropriate evacuation plan for the facility. T h e plan should be written with accompanyin~ diagrams and distributed to each supervisor and posted in appropriate Iocauons for all employees to read and study. In addition |o fires and explosions, the evacuation plan should also consider other hazardous events such as spills, leaks or releases of flammable, toxic or radioactive ma- r and acts of nature, such as tornadoes, hurricanes and floods.

The evacuation plan should cover, but not be limited to describing: (I) Under what conditions evacuation will be necessary. (2) Method of alarm transmission.

428 4 5 - 2 4 LABORATORIES USING CHEMICALS

4-6 .3* M a i n t e n a n c e P r o c e d u r e s . M a i n t e n a n c e p roceduf f~ sha l l be e s t ab l i shed . S u c h p r o c e d u r e s sha l l i n c l u d e t h e inspec t i0 th t e s t i ng a n d m a i n t e n a n c e of:

(a) U t i l i t i e s - s t e a m , gas, e l ec t r i ca l

(b) A i r s u p p l y a n d e x h a u s t sys t ems

(c) F i r e p r o t e c t i o n

(d) D e t e c t o r s a n d a l a r m s

(e) P r e s s u r e a n d t e m p e r a t u r e re l i e f va lves

(f) W a s t e d i sposa l sys t em

Appendix A (continued) (3) Action to be taken on receipt of alarm in addition to evacuation (i.r

turn off flames, other ignition sources). (4) Exit mutes: Primary and alternate mutes to horizontal and vertical

exits leading to the exterior of the building or safe refuge zones as may be per. ,nitted if total evacuation of the facility is not required and the alarm system b appropriately zoned.

(5) Instructions necessary to prevent evacuees from hampering fire fightenh or emergency organization from proceeding with essential duties (i.e., move away'from the' building to a pre-designated area).

(6) Accountability to determine if everyone has left the facility: Wardens or supervisors instructed on sound of the alarm to cheek all occupied spaces in their assigned area to ensure that everyone has heard the alarm and is evacuat. ing. Personnel from particular groups, departments, floors or areas to gather in a predesignated area outside of the building or in the safe refuge zone. Special procedures established for evacuation of handicapped persons. Floor or area fire warden or group supervisor t o h a v e responsibility to account for everyone. (Normal sign-in-sign-out procedures may be helpful if they also include visitor, and guests.)

(7) Methods to notify personnel when it is safe to re-enter the facility.. (Dependence on duly authorized persons, such as wardens, to pass this word will prevent someone from entering the facility prematurely.)

b. Laboratories should hold fire exit drills at least once a year to test the evacuation procedure by familiarizing occupants with exits, particularly emergency exits not normally used, and their safe and ellicicnt use.

NOTE: For required frequency of fire exit drills in educational occupancies, see 'Code for Safety to Life from Fire in Buildings and Structures, ' NFPA No. 101 - - 1973. Fire exit drills differ fromfire drills in that the latter are held for the purpose of fire fighting practice by the fire brigade or other emer- genc}, organizations. Since a conflict exists between evacuation and fire fighung, management should appoint different. . persons to be. responsible. for each procedure, as one cannot effeeuvcly direct fire fighting operauons and evacuation simultaneously.

c. Fire alarm systems, where available, should be used in the conduct of fire exit drills. No one should be excused from participating in a drill as it may fail its intended purpose in a real fire.

A4-6.3 Successful prevention or extinguishment of fires and protection of personnel from injury due to fire or contingent conditions requires an adequate maintenar~.ee program. Appendix C outlines additional advisable equipment inspection, testing and maintenance programs for a laboratory beyond those required by this Standard.

EXPLOSION HAZARD PROTECTION 429 45-25

Chapter 5 Explosion Hazard Protection

5.1 General.

5-1.1 When a laboratory unit is considered to contain an ex- flosion hazard as defined in 2-1.2.1, appropriate protection shall

provided to protect occupants of the laboratory unit, of adjoining laboratory units and of nonlaboratory areas.

5.1.2 Protection shall be provided with one or more of the following:

(a) Providing special preventive or protective measures for the reactions, equipment or materials themselves, e.g., explosion suppression, high speed fire detection with deluge sprinklers or explosion-resistant enclosures.

(b) Using remote control to minimize personnel exposure. (c) Carrying out experiments in a detached or isolated building. (d) Providing explosion-resistant walls or barricades for the hazardous laboratory.

(e) Limiting amounts of flammable or reactive chemicals exposed by experiments. (f) Providing explosion venting in outside walls sufficient to maintain the integrity of the walls separating the hazardous laboratory unit from adjoining areas.

5.2 Exploslon-Resistant Construction.

5-2.1 When explosion-resistant construction is used, explosion resistance shall be achieved by one of the following:

~a) Reinforced concrete walls. (b) Rodded and filled concrete block walls. (c) Steel walls of adequate thickness and design adequately

supported. (d) Steel plate walls with energy-absorbing lining.

(e) Barricades such as those used for explosives operations constructed of reinforced concrete, sand-filled wood sandwich, wood-lined steel plate, earth or rock berm.

5-3 Explosion Venting.

5.3.1 When explosion venting is used, explosion venting shall


be designed and located so that:

(a) Fragments will not strike other occupied buildings or area8 or

(b) Blast mats, energy-absorbing barrier walls or earth or rock berms will interrupt the flight of fragments.

NOTE: Guidance on venting explosions of flammable vapors, gases and dusts is contained in the 'Guide for Explosion Venting', NFPA No. 68 1954. Information on explosion-resistant 'construcuon is available in several publications (see references D2, D3, D17, D18, DIg, D20, D21 and D22 in Appendix D.)

5--4 Unauthor ized Access.

5-4.1 Appropr ia te doors, gates, fences or other b a r r i e r s properly posted shall be provided to prevent or restrict access to explosion hazard laboratories and to the space between the explosion venting means and the fragment barrier.

VENTILATING SYSTEMS

431 45-27

Chapter 6 Ventilating Systems

6-1 General .

6-1.1 Basic Standards.

6-1.1.1 Except as supplemented by the requirements of this ~hapter, duct systems for laboratory heating and ventilating, includ- t ,g warm air heating systems, general ventilating systems, air cool- filg systems, and laboratory exhaust and hood exhaust systems, shall r with the Standard for the Installation of Air Conditioning and |*r Systems, .NFPA .No. 9 0 A - 1973, and with the Standard

r the Installation of Blower and Exhaust Systems for Dust, Stock and or Removal or Conveying, .NFPA .No. 9? ~ 7973, as these systems

|h3rticularly relate to laboratory installations.

6-2 Supply Systems.

6-2.1 Outs ide Air Source.

6-2.1.1 The location of fresh air intakes shall be chosen to ovoid drawing in f lammable or toxic materials or by-products of combustion coming either from the laboratory building itself or other structures and devices.

6.2.2 Air Distr /butlon.

6-2.2.1" Laboratory units in which flammable materials are r or used shall be maintained air negative to the corridors or 0djacent spaces.

Exception: Where operational activities such as those requiring clean rooms ~ttclnde a negative pressure in relation to surrounding spaces, special precautions shall be taken to prevent escape oaf the atmosphere in the laboratory unit to the surrounding spaces.

6-2.2.2 Care shall be exercised in the placement of air tupply diffusion devices to avoid air currents that would adversely affect the capture velocity of laboratory hoods.

Appendix A (continued) A6-2.2.1 Air should not be recycled within or.from any laboratory space in

which flammable, combustible or toxic mate/ials are used in quantities which may prove dangerous to those persons, working within the laboratory or other tpaces on the same principal air handling system.


6-5 Exhaus t System.

6-3.1 Exhaus t Ai r Discharge .

6-3.1.1 Air exhausted from laboratory spaces or appara tus to the outside shall not pass unduc ted through other spaces.

6-3.1.2" Air conta in ing f lammable or toxic mater ial shall be discharged in ductwork systems main ta ined at a negative pressure in relation to the pressure in the sur rounding space within the building.

Exception: The pressure in the ductwork system need not be negative in relation to the air pressure of the surrounding space if spedal precautions are taken to prevent discharge of materials through the walls of the ducts. Portions of the ductwork systems which are under positive pressure shall be seamless, braised, welded or soldered construction to prevent escape of materials through the walls of the ducts.

6-3.1.3" Labora tory hood face velocities shall be sufficient to assure a capture velocity into the hood for the opera t ing conditions.

6-3.1.4 Local or spot exhaust systems, e.g., snorkels (ele- phan t trunks), shall have sufficiently high velocities to capture the par t icular materials being emitted.

�9 Appendix A (continued)

A6-3.1.2 The intent of 6-3.1.2 is to require permanent installations which will positively prevent escape of materials to any space within the building. Installations which are only partially effective or which are subject to de- terioration are not included vnthin this intent.

A6-3.L3 The American Industrial Hygiene Association and the American Conference of Governmental Industrial Hygienists have published guides on recommended minimum air velocities at the working face of laboratory hooch. (See reference D4 and D5 in Appendix D.)

(a) The following recommendations have been based on those guides: i. For materials of extreme toxicity or hazard, such as tetraethyUead,

berylium compounds, metal carbonyls and volatile carcinogens, the recommendations for average velocity at the hood opening range from 125 to 150 feet per minutewith minimums at any one point of 100 to 125 feet per minute.

2. An average velocity of 100 fpm (minimum at any one point, 80 fpm) is recommended generally for all laboratory hoods except those previously men. tioned that offer extreme potential hazards.

3. For these operations where the hazard is not high, that is, where materials of low toxicity such as acetone, ethanol, and straight-chain hydro- carbons are used, and for operations creating nuisance dusts and fumes, the recommendations for average face velocity range from 75 to 80 fpm and for a minimum velocity at any one point from 50 to 60 fpm.

VENTILATING SYSTEMS

433 45-2.q

6-3.2 Duct Construct ion for H o o d s a nd Other Local Exhaust Systems.

6-3.2.1 Laboratory hood ducts shall be constructed of noncombustible materials.

I'~xception No. 1: Combustible ducts may be used iJ enclosed in a shaJt oJ noncombustible construction where they puss through nonlaboratory areas or through laboratory units other than tlw. unit which tier serve.

Exception No. 2: Combustible ducts may be used if all areas through which they pass are protected with an approved fire extinguishing system as described in Chapter 4.

6-3.2.2 Combustible ducts or duet linings, when used in new installations or as replacements, shall have a flame spread of 25 or less when tested in accordance with Test .[or SurJace Flammability of Material Using a Radiant Heat Energ o, Source, A S T M E762-67, (see r~arenCe D6 in Appendix D) or Method of Test oJ Surface Burning

ncteristics oJ BuiMing Materials, aVFPA .No. 2 5 5 - 1972. Test ~pecimens shall be of the minimmn thickness used in the construction of the duct. Where results obtained by tests conducted b y different test methods vary, those obtained by NFPA No. "255 shall prevail.

NOTE: For construction of perchloric acid fume hoods and ducts see Section 9-2.9.

6-3.2.3 Ducts shall be of adequate strength and rigidity to Incet the conditions of service and installation requirements, and shall be properly protected where subject to mechanical injury.

6-3.2.4 Vibration isolation connectors shall comply with the requirements for ducts in 6-3.2.1.

6-3.2.5 Flexible connectors containing pockets in which con- vcyed materials may collect shall not be used in any concealed space, or where strong oxidizing materials, e.g., perchloric acid, are used.

6-3.2.6 Controls and dampers, where required for balancing of the exhaust system, shall be of a type that in the event of failure due to fire or corrosion, fails open (will open) to assure continuous draft.

6-3.2.7* Hand holes if installed for damper, sprinkler or fusible link inspection or resetting and for residue clean-out purposes, shall be equipped with tight-fitting covers provided with substantial fasteners.

Appendix A (continued) A6.-3.2.7 Automatic fire dampers should be omitted from laboratory local

exhaust systems.


6-3.2.8 Fire detectors and alarm devices shall not auto. tnatically shut off exhausters (fans) except as required when actunt. ing halon or carbon dioxide fire extinguishing systems.

6-3.3 Duct Velocities for Hoods and Other Local Exhaust Systems.

6-3.3.1" Laboratory air' exhaust systems shall be maintained at velocities sufficiently high to minimize deposition of materials being emitted into the hood chamber, or otherwise pulled into the exhaust system.

6-3.4 Exhausters (Fans).

6-3.4.1 Fans shall be selected with due consideration to the fire, explosion and corrosion problems.

6-3.4.2 Fans for conveying both corrosive materials and flammable or combustible materials may be lined with or constructed of corrosion-resistant materials having a flame spread of 25 or less when tested in accordance with Test for Surface Flare. inability of Materials Using a Radiant Heat Source, ASTME 762-67 (See reference D6 in Appendix D) or Method of Test of Surface Burning Clutracteristics of Building Materials, .NFPA .No. 255--7972. Test specimens shall be of the minimum thickness used in the construction of the fan. Where results obtained by tests conducted by different test methods vary, those obtained by NFPA No. 255 shall prevail.

6-3.4.3 Fans shall be so located and arranged as to afford ready access for repairing, cleaning, inspection, and lubricating.

6-3.4.4 When flammable dusts or vapors are passed through the fans, the rotating element shall be nonferrous or nonsparking material, or the casing shall consist of or be lined with such material. Where there is a possibility of solid foreign material passing through the fan that would produce a spark, both the rotating element and the casting shall be constructed of nonferrous or nonsparking material. Nonferrous or nonsparking materials shall meet the flame spread test requirement for fans in 6-3.4.2.

Arpendix A (continued)

"-3.3.1 See Industrial Ventilation: A Manual of Recommended Practices, h Edition, American Conference of Governmental Industrial Hygienists.

" "erence D5 in Appendix D.)

V E N T I L A T I N G S Y S T E M S 435 45-31

6-3.5 P o w e r and Control.

6-3.5.1 Motors and their controls shall be located outside of Ihe location in which flammable or combustible vapors or ducts are being generated and removed unless of the type approved for the particular conditions or hazard.

6-4 Inspection and Maintenance of Ventilation Equipment .

6-4.1 Detectors and Alarms.

6-4.1.1 Air system flow detectors, when installed, shall be inspected at least annually. Where potentially corrosive or ob- structive conditions exist, the inspection frequency shall be in- creased appropriately. Velocity and pressure-sensing detectors shall be tested at each inspection. Low-flow or no-flow alarms of the visible (lights) or audible (e.g., horns, bells) type shall be tested for correct ~ operation at least at each inspection. Signal transmission for alarms designed to activate signals at more than one location shall be verified at each location during each inspection.

6-4.2 Fi/ters.

6-4.2.1 Fixed fire extinguishing systems provided for the protection of filters shall be inspected quarterly for accumulation of combustible material deposits on nozzles and cleaned as required. (See Appendix C for recommendations for additional inspection and testing maintenance.)

6-4.3 Fans and Motors.

6-4.3.1 Air supply and exhaust fan and motor components shall be inspected at least annually. (See Appendix Cfor recommendations.for additional inspection and testing maintenance.)

6-4.3.2 When air flow detectors are not provided or mea- sured air flow tests are not made quarterly, fan belts shall be inspected quarterly. Frayed or broken belts shall be replaced promptly. Where double sheaves and belts are employed, the inspection frequency may be semi-annually.


Chapter 7 Chemica l Storage, Handling and Waste Disposal

7-1 O r d e r i n g .

7-1.1 Procedures.

7-1.1.1" When a chemical is ordered, steps shall be taken to determine the hazards and to t ransmit that informat ion to those who will receive, store, use or disposc of the chemical. Restrictions imposed by governmenta l regulations and in-house rules shall be followed.

NOTE: Information sources are Hazardous Chemicals Data, NFPA No. 49 - - 1973, Manual of Hazardous Chemical Reactions, NFPA No. 491M - - 1971, Flash Point Index of Trade Name Liquids, NFPA No. 325A-- 1973 and Fire-Hazard Properties of Flammable Liquids, Gases and Volatile Solids, NFPA No. 325M - - 1969. See also the Chemical Safety Data Sheets, published by the Manufacturing Chemists' Agqociatlon. (See reference D19_ in Appendix D. )

7-2 Handling and Storage.

7-2.1 Facil i t ies.

7-2.1.1 Hazardous chemicals shah not be brought into the laboratory complex unless design, construct ion and fire protection of receiving and storage facilities are commensura te with quanti t ies and hazards of chemicals involved.

7-2.1.2 Special storage facilities shall be provided for materials having un ique physical or hazardous properties such as temperature-sensitive, water-reactive, and explosive materials.

NOTE: Guidance on unique physical or hazardous properties will be found in Hazardous Chemicals Data, NFPA No. 4 9 - 1973, the Manual of Haz- ardous Chemical Reactions, NFPA No. 491M--1971, and Code for the Manufacture, Transportation, Storage, and Use of Explosive Materials, NFPA No. 495 - - 1973.

7-2.2 H a n d l i n g .

7-2.2.1 Receiving, t ransport ing, unpacking, and dispensing of chemicals and other hazardous materials shall be carried out by trained personnel in such locations and m a n n e r as to minimize hazards from flammable, reactive or toxic materials.

Appendix.A (continued)

A7-I.LI Before a hazardous chemical is ordered, controls should be established to assure that adequate facilities and procedures arc available for receiving, storing, using, and dmposing of the material.

Table 7-1. Maximum Allowable Size of Containers

Container Type Class IA 1

Flammable Liquids

Class IB s Class 1C a

Combustible Liquids

Class II + Class I I I ~

Glass 1 pt. e

Metal (other than DOT Drums) or approved plastic 1 gal.

Safety Cans 2 gal.

Metal Drums (DOT Spec.) 5 gal.

I qt. e I gal. 1 gal. 5 gal.

5 gal. 5 gal. 5 gal. 5 gal.



Class IA liquids arc those having flash points below 73~ (22.8~ and boiling points below 100~ (37.8~

s Class IB liquids are those having flash points below 73~ (22.8~ and boiling points at or above 100~ (37.8~

* Class IC liquids are those having flash points at or above 73~ (22.8~ and below 100~ (37.8~

4 Clm II liquids arc those having flash points at or above 100~ (37.8~ and below 140~176

6 Class III liquids are those having flash points at or above 140~ (60~

e Sizes as large as 1 gallon may be used if needed and ff the required liquid purity would be adversely affected by storage in metal or if the liquid would cause excessive corrosmn of the metal container.


7-2.2.2 Before the ini t ial use of a chemica l mater ia l , the user shall be made thoroughly famil iar with its hazards. He shall follow such hand l ing procedures as are appropr i a t e .

7-2.2.3 Before a chemica l mater ia l is used, the user shall de t e rmine tha t informat ion and facil i t ies are avai lab le to provide safe disposal of haza rdous mater ia ls and waste products .

7-2.3* Storage.

7-2.3.1 H a z a r d o u s chemica l inventories in a labora tory ' s s torage facil i ty shall be wi thin the prescr ibed capaci t ies of the facility

for the various kinds of chemicals.

7-2.3.2 T h e quant i t ies of hazardous chemicals wi th in each l abo ra to ry uni t shall not exceed the pe rmi t t ed quant i t ies in Chapter 2 and T a b l e 2-1.

7-2.3.3 Haza rdous chemicals in the open in laborator ies shall be kept to a m i n i m u m necessary for the work being done.

7-2.3.4" Con ta ine r types and m a x i m u m capaci t ies shall comply with T a b l e 7-1, except tha t Class 1A and Class 1B f lammable l iquids m a y be stored in glass conta iners of not more than one- gal lon capac i ty if the requ i red l iquid pur i ty would be affected by s torage in meta l conta iners or if the l iquid would cause excessive corrosion of the meta l conta iner .

Exception: Sixty-gallon drums are permitted in approved storage rooms.

NOTE: Table 7-1 is taken from Table IV-I in the Flammable and Com- bustible Liquids Code, NFPA No. 30 - - 1973.

7-2.3.5 I n c o m p a t i b l e mater ia l s shall be segregated to prevent acc iden ta l con tac t wi th one another .

NOTE: For guidance see, Hazardous Chemicals Data, NFPA No. 49 - - 1973 and The Manual of Hazardous Chemical Reactions, NFPA No. 491M m 1971.


A7-2.3 Flammable and combustible liquids that are not in me sho.uld bc stored in safety cans, storage cabinets, or storage rooms.

A7=2.3.4 Class IA and Class IB flammable liquids in glass containers larger than the l-pint and l-quart sizes permitted in Table 7-1 should be stored in metal pails or other suitable containers of sufficient size to hold the liquid in the glass container.

CHEMICAL STORAGE, HANDLING~ WASTE DISPOSAL 439 45-35

7-2.3.6 Laboratory and storage facilities shall be inspected to ensure compliance with the provisions of this standard.

7-3" Collec'tion and Disposal of Chemical Waste.

7-3.1 General.

7-3.1.1 The handling, storage and transportation of chemical waste shall be subject to the provisions in this standard for the handl- I,g, storage, and transportation of chemicals.

7-3.2 Collection.

7-3.2.1 Special consideration shall be given to the classification of chemical waste at the time of collection so as to avoid chemical incompatibilities.

7-3.3" Disposal.

7-3.3.1 Disposal of chemical waste material shall be in accordance with good safety practices and applicable governmental regulations.

7-3.3.2 Persons or agencies employed to remove chemical waste from the premises shall be apprised of the basic character and hazards of the waste.

Appendix A (continued) A7-3 Drain line traps from laboratory benches, hood floors, mechanical

r rooms, etc., should have water added at regular intervals to assure that traps will not be the source of flammable or toxic vapor release. Where ~lf .primmg traps are provided, an annual inspection for proper operation should be made.

NOTE: Additions such as white oil are sometimes used to reduce evapo- ration of water from traps.

A7-5.3 T h e Laboratory Waste Disposal Manual , pul~lislaed by the Manu- facturing Chemists' Association, (see reference DI4 in Appendix D) contains recommendations for the safe disposal of some 1200 chemicals. The guidance Of a technically qualified person is recommended for disposed of hazardous chemicals.


Chapter 8 Compressed or Liquefied Gases

8-1 Storage a n d Piping Systems.

8-1.1 Method of storage and piping systems for compressed gases and liquefied gases shall comply with the requirements of the appl icable NFPA, CGA and ANSI standards where they exist.

NOTE 1. Applicable Standards of the National Fire Protection Association include: Standard for Bulk Oxygen Systems at Consumer Sites, NFPA No. 5 0 - 1973, Standard for Gaseous Hy~lrogen Systems at Consumer Sites, NFPA No. 5 0 A - 1973, Standard for Liquefied Hydrogen Systems at Consumer Sites, NFPA No. 50B - - 1973, Standard for the Installation of Gas Appliances and Gas Piping, NFPA No. 54 - - 1969, Standard for the Installation of Gas Piping and Gas Equipment on Industrial Premises and Certain Other Premises, NFPA No. 54A - - 1969, Standard for the Storage and Handling of Liquefied Petroleum, Gases, NFPA No. 58 - - 1972.

NOTE 2. Applicable Standards of the American National Standards Institute include B31.1.0 - - 1967, Power Piping with Addenda, B31.1.0a - - 1971 (Second Edition), B31.1.0b - - 1971, B31.1.0c - - 1972, and B31.1.0d - - 1972 (see reference D7 in Appendix D.); B31.2 - - 1968, Fuel Gas Piping (See reference D8 in Appendix D.); B 3 1 . 3 - 1966, Petroleum Refinery Piping. (see reference D9 in Appendix D.).

NOTE 3. Applicable Standards of the Compressed Gas Association including P-I, Safe Handling of Compressed Gases (see reference Dl l in Appendix D.).

8-1.2 Systems for other gases and for cryogenic materials shall comply with the manufac turer ' s design and specifications.

8-1.3 Rel i e f Va lves a n d Shutoffs.

8-1.3.1 M a n u a l shutoff valves shall be provided at all points of supply and points of use.

NOTE. Some facilities also have shutoff valves in an accessible location outside of the space in which the gas is being used.

8-1.3.2 The gas supply to each bui ld ing shall be provided with an exterior shutoff valve.

Exception. I f the containers supplying the piping system are equipped with shutoff valves a separate valve on the piping system is not required.

8-1.4 Iden t i f i ca t ion of P i p i n g .

8-1.4.1" Piping shah be identified as to its contents.

Appendix A (continued) A8oi.4.1 The marking should be in conformance with ANSI Standard

A13.1 - - 1956, Standard Scheme for the Identification of Piping Systems (see reference D10 in Appendix D) or it should be in conformance vnth some other recognized scheme.

COMPRESSED OR LIQUEFIED GASES 441 45-37

8-1.4.2 P e r m a n e n t p ip ing shall be marked at both the ~10pply and discharge ends with the name of the mater ia l to be piped.

8-1.4.3 Piping systems, inc luding regulators, shall not be ~tr for gases o ther than those for which they are designed and ~lentified.

8-2 C o m p r e s s e d or Liquefied Gas C y l i n d e r s .

8-2.1 T h e following requi rements a p p l y to compressed or C!quefied gas cyl inders con ta in ing hazardous chemicals or oxygen.

8-2.2 Cyl inders shall be hand led and stored as specified in NFPA S t a n d a r d s Nos., 50, 50A, 50B and 58 as identif ied in 8-1.1, ~ltd as specified in Section 3 of G C A p a m p h l e t P- l , Safe H a n d l i n g of (h~mpressed Gases. (see reference D 11 in Appendix D.)

8-2.3* Size, quan t i t y and re tent ion l imi ta t ions for cyl inders in ~tboratory units shall be in accordance wi th T a b l e 8-2.

8-2.4 All cy l inders shall be secured in place to prevent falling.

Table 8-2 Size, Q u a n t i t y a n d R e t e n t i o n L i m i t a t i o n s for C o m p r e s s e d o r L i q u e f i e d Gas C y l i n d e r s

Maximum Size Cylinder

Flammable Liquefied Gases with Gases Flammable Health Hazard

and Oxygen Gases Rating 2, 3, or 4

I Approximate Dimensions n inches) 10 by 50 9 by 30 5 by 15

Maximum No. Cylinders Per 500 square feet or Less I 2 2 3 n

Maximum Retention Period s 36 Months 36 Months 6 Months

O No more than 15 cylinders shall be permitted in any laboratory unit except qhat up to 25 2-inch by 12-inch cylinders shall be permitted.

t Cylinders of gases with health hazard rating 2 and with no warning property, find cylinders of all gases with health hazard rating 3 or 4 shall be kept in a r mechanically ventilated hood or other continuously mechanically ventilated enclosure. There shall be no more than two cylinders of gases with health hazard rating 3 or 4 per hood or other enclosure.

t (~%/linders shall be returned to their suppliers after the expiration of the retention period.

c ~

Appendix A (continued) A8-2.3 Cylinders not in active use should be removed from laboratory units

q0 it storage facility as described in CGA P-l, Safe Handling of Compressed Oases. (see reference D11 in Appendix D.)

442 45-38 L A B O R A T O R I E S U S I N G C H E M I C A L S

Chapter 9 Laboratory Operations and Apparatus

9-1 Operations.

9-1.1 Hazards of Reactions and Chemicals.

9-i.1.1 Before laboratory reactions or tests are begun, a~ evaluation shall be made for hazards that may be encountered 0~ generated during the course of the work. This evaluation shall in, elude hazards associated with the properties and reactivity of thf materials used, hazards associated with the operation of the equip, ment at the operating conditions, and hazards associated with the nature of the proposed reaction (e.g., oxidation, polymerization)~

NOTE: Suitable sources are Hazardous Chemicals Data, NFPA No. 49 -- 1973, Manual of Hazardous Chemical Reactions, NFPA No. 491Mq 1971, Flash Point Index of Trade Name Liquids, NFPA No. 325Aq 1972, Fire Hazard Properties of Flammable Liquids, Gases and Volatile Solids, NFPA No. 3 2 5 M - 1969, and Chemical Safety Data Sheets s published by the Manufacturing Chemists' Association. (see reference D12 in Appendix D.)

9-1.1.2 Periodic reviews of laboratory operations and pro. cedures shall be conducted with special attention given to any change in materials, operations or personnel.

9-1.1.3" Where reactions are being performed to synthesize materials whose hazard characteristics have not yet been deter. mined by test, precautions shall be employed to control the highes! hazard possible based on a known hazard of similar material. Where the new material may present a severe explosion potential, initial experiments or tests shall be conducted in a suitable enclosure using minimal quantities and with appropriate protection for the operator. (See Chapter 5.)

9-1.1.4 Unattended operations and automatic laboratory equipment shall be provided periodic surveillance for abnormal operation. (See also 9-1.Z3.)

9-1.1,5 Open flame or open filament heating of flammable liquids and similarly hazardous procedures shall be attended and shall be conducted with adequate ventilating air exhausting to the outside.

Appendix A (continued) Ag-I. L3 When produced, the new material should be subjected to a complete

haz.ar.d, analysis including differential thermal analysis, drop weight shoclt sensmvtty, autoignition temperature, flash point, thermal stability under con. finement, heat of combustion, and other appropriate tests.

443 LABORATORY O P E R A T I O N S AND A P P A R A T U S 45-39

9-1.2 Heat ing Operations. 9-1.2.1 All heating of flammable or combustible liquids

,t',~11 be conducted so as to minimize fire hazards.

9-1.2.2 Provision shall be made to contain spilled liquid by i,J0vlding metal catch pans or other heat-resistant noncombustible ~ ~'eptacles of suitable size for glass apparatus containing 250 cubic E ,~altmeters of flammable liquid or 250 cubic centimeters of com- t';;~tible liquid if heated to its flash point. Suitable supplementary I~ ~ extinguishing equipment shall be available if necessary.

9-1.2.3 Unattended operations shall be provided with over- t,':~c control and automatic shutdown to prevent system failure that I Oil result in fire or explosion.

9-1.2.4 Strong oxidizing materials, such as perchloric acid, ~'~11 not be heated by gas flames or oil baths.

9-1.3 Distillation Operations. 9-1.3.1 Distillations shall be conducted in suitable equip-

, ~0t properly assembled with consideration being given to fire (' ~e.ards from vent gases and possible equipment breakage or failure. (' _~re shall be taken to avoid the presence of unstable components L i Ihe still pot (e.g., peroxides) and to avoid overheating still con- t:at~. Metal catch pans or other heat-resistant noncombustible re- I ci)lacles of a suitable size shall be utilized beneath pots and re- I c~vers with volumes above 250 cubic centimeters in glass ap- [,,~ratus.

9-1.3.2 Glass equipment for distillations, and particularly ~:~uum distillations, shall be inspected for cracks, scratches, or I ~|ter defects prior to each use. Faulty glass equipment shall be ~'~arded.

9-1.3.3 Glass vacuum equipment shall be shielded during

9-1.4 Other Separation Operations.

9-1.4.1 Filtrations, extractions, sublimations, adsorptions, ~ttporations, and other separation techniques, including centrifug- i~b that involve flammable or combustible materials shall be pro- l'~ted from ignition sources and shall be furnished with suitable ~r

9-1.5 Mixing and Grinding Operations.

9-1.5.1 Mixing, grinding, stirring and agitation operations i~volving flammable and combustible materials shall require the


s a m e precautions against fire as in Section %1.4.1. Precautions shall be taken to avoid local overheating which may occur during grinding and mixing of solids. Care shall be taken to avoid fire or explosion hazards from dusts and flammable solvents.

N O T E : The NFPA has published 17 standards for the control of hazards of combustible dusts.

9-1.6 Other Operations. 9-1.6.1 Other laboratory operations, such as reactions at

temperatures and pressures above or below ambient conditions shall be conducted in such manner that hazards will be minimized. Shielding shall be utilized whenever there is a reasonable probability of explosion or vigorous decomposition and associated hazards~ during charging, reaction sampling, venting and discharge ot products. (see also Chapter 5 and 9-2.6.3.)

9-1.6.2 Quantities shall be limited and procedures develope~ to control or isolate vigorous or exothermic reactions.

N O T E : Approaches include chilling, quenching, cut-off of reactant supply, venting, dumping, "short-stopping" or inhibiting.

9-1.6.3 During drying operations in which flammable o: combustible vapors are involved, suitable procedures shall be fol lowed to condense, trap or vent such vapors and to avoid ignitio~ sources .

9-1.6.4 Spraying of flammable or combustible paint anq varnishes shall conform with the requirements of the Standard f l Spray Application Using Flammable and Combustible Materials, .NFP, .No. 3 3 - 1973.

9-1.6.5 Flammable liquids stored in refrigeration equipmer shall be in closed containers. (see also 9-Z3.)

9-2 Apparatus. 9-2.1 General .

9-2.1.1 Apparatus shall be installed in conformance wi! applicable requirements of NFPA standards, including the .Nation Electrical Code, .NFPA .No. 70 ~ 1971.

9-2.1.2 Operating controls shall be accessible under norm and emergency conditions.

9-2.2 Heating Equipment.

9-2.2.1 All unattended electrical heating equipment shall 1 equipped with an overtemperature shutoff switch in addition

445 LABORATORY OPERATIONS AND APPARATUS 45-41

normal temperature controls if overheating could result in a fire or explosion.

9-2.2.2 Heating equipment with circulation fans shall be equipped with an interlock arranged to disconnect current to the heating elements when the fan is inoperative.

9-2.2.3 Burners, induction heaters, ovens, furnaces and other heat-producing equipment shall be located a safe distance from areas where temperature-sensitive and flammable materials and compressed gases are handled.

9-2.2.4 Oven and furnace installations shall conform with the requirements of the Standard for Ovens and Furnaces, .NFPA .No. 8 6 / 1 - 1973.

9-2.3 Refr igera t ion and Cooling Equ ipment .

9-2.3.1 Refrigerators or cooling equipment used to store or r f lammable liquids shall be designed or modified so that the storage compartment , including the door and door frame, meets the requirements for Class I, Division 1 locations, as described in Article 501 of the National Electrical Code, .NFPA No. 70 - - 7971. All electrical equipment mounted outside of the storage compar tment lihall either:

(a) Be suitable for Class I, Division 2 locations if located in areas such as the machine compar tment at the bot tom of the refrigerator where hazardous vapors may be present due to leakage or opening of the storage compar tment door; or

(b) Installed above the storage compar tment or on the Outside surface of the refrigerator where exposure to hazardous concentrations of vapors will be minimal; or

(c) Be installed in a location subject to positive ventilation laherent in the refrigeration which prevents accumulations of hazardous concentrations of vapors.

9-2.3.2 Each refrigerator shall be prominently labeled to htdicate whether it is or is not suitable for storage of flammable |lquids.

9-2.4 Constant Temperature Baths.

9-2.4.1 Electrically heated constant temperature baths shall b~ equipped with an overtemperature shutoff switch in addition to t',0rmal temperature controls if overheating could result in a fire or f~plosion.

446 45-42 L A B O R A T O R I E S U S I N G C H E M I C A L S

9-2.4.2 Baths handling flammable liquids or combustible liquids heated to their flash point shall be placed in a laboratory hood, or otherwise vented to a safe location to control vapors.

9.2.5 Motor-Driven Apparatus.

9-2.5.1 Motols used to drive overhead stirrers in open containers of flammable or combustible liquids shall be approved for Class I, Division 2 locations as defined in Section 500-2 of the National Electrical Code, .~fFPA .No. 7 0 - - 7971.

9-2.6 Pressure Equipment.

9-2.6.1 Equipment used at pressures above 15 psig shall be designed and constructed for use at the expected pressures. Pressure vessels require specialized design outside the scope of normal work- shop practice.

NOTE: For design of pressure vessels, see ASME Boiler and Pressure Vessel Code, Section VIII, Rules for Construction of Pressure Vessels, Division 1, 1971 Edition. (see reference D13 in Appendix D.)

9-2.6.2 Pressure equipment shall be fitted with a suitable pressure-relief protective device, e.g., rupture disc, relief valve, etc. The pressure-relief device, i f used, shall be vented to a safe location.

9-2.6.3 Al l equ ipmen t involving pressures above 15 psig, such as autoclaves, sterilizers and calorimetry bombs shall be used in compliance with the manufacturer's instructions or design limita- tions. This equipment shall be regularly examined and a log kept for corrosion, cracks, distortion, weakening of closure, difficulty in maintaining pressure, scale formation, and general chemical attack. If any significant change in the condition of the equipment is noted, it shall be taken out of service immediately and tested or inspected by a suitably-qualified person. If its conditions have been found to be affected, it shall be discarded or, if appropriate, derated.

9-2.7 Analytical Instruments.

9-2.7.1 Instrumentation such infrared, ultraviolet, atomic absorption, X-ray and mass spectrometers, chromatographs, and thermal analyzers shall be installed in accordance with the manufacturer's instructions and applicable NFPA codes pertaining to venting, piping and wiring for such equipment.

9-2.7.2 Analytical instruments shall be operated in accordance with the manufacturer's or other approved recommenda- tious, or in such other manner as to minimize hazards to personnel from high voltages, fumes or vapors, radiation, flames, flashback& and explosions.

447 L A B O R A T O R Y O P E R A T I O N S AND A P P A R A T U S 45--43

9-2.8 Laboratory Hoods.

9-2.8.1 Laboratory hood services shall be installed in ac- I,~tnlanee with applicable NFPA Standards. For new installations or t~glifications, all service controls (e.g., electric, gas, water, air) and ~;~retrical receptacles shall be immediately external to the hood and ~ilhin easy reach. In existing installations where service controls ~ e inside the hood, additional shutoff devices shall be within 50 f,'et of the hood and shall be accessible and clearly marked. Light- 12|I ~hall be sealed.

9-2.8.2 For new installations or modifications of laboratory I':~tds the countertop, interior walls and ceiling, and front sash (if ~:fovided) or apron shall be made of materials having a flame 4~tj}read index of 25 or less when tested in accordance with A S T M E

2-67, Test .for Surface Flammability oJ Materials Using A Radiant Oltt~t Energy Source. (see reference D6 in Appendix D.) Materials shall be ('zaled in the same form and thickness as used in the..hood.

9-2.8.3 The hood shall provide confinement of the possible ~,:~zards and protection of personnel for the test work for which it is Uatended. Hood face velocities shall maintain a positive air flow into ~he hood.

NOTE: For air velocities at the laboratory hood face see 6-3.1.3.

9-2.8.4 Laboratory hoods shall be located in areas of mini- eaum air turbulence. The location shall not block egress from the ~3boratory in the event of fire in the hood. (See 3-3.2.1.)

9-2.8.5 Laboratory hood face (capture) velocity shall be 6becked at least annually to determine that the hood is operating ~~0perly. In addition, laboratory hood face velocities shall b e ~hecked after any adjustment to the ventilation balance. De- ~iencies shall be corrected or (a) the hood shall be temporarily fr162 and the hood activity brought in line with the re- 6|a~ification or (b) the hoods shall not be used.

9-2.8.6 A sign shall be affixed to the hood listing the in- direction interval, the latest inspection date, the normal hood face tr the classification of the hood based on the cur rent ' in - 4~lection data, and the inspector's name. In lieu of a hood sign, a !~'operly maintained log of all hoods giving the same information ~ acceptable.


9.2.9* Perchloric Acid F u m e Hoods.

9.2.9.1 Perchloric acid fume hoods, duct work, and cx, haust fans shall be constructed of materials resistant and imperviout to perchloric acid.

9.2.9.2 Sealants that do not react with perchloric acid shall be used with hood, duct work, and exhaust systems.

9.2.9.3 Ducts shall take the shortest and straightest path to outdoors and shall not be manifolded with other exhaust systems, Duct work shall consist of sealed sections. Horizontal runs shall be as short as possible, and there shall be no sharp turns. The duel work shall provide a positive drainage slope back into the fume hood,

9.2.9.4 A water spray shall be provided for washing down the hood and exhaust system. The hood work surface shall be water- tight with a minimum depression of one-half inch at the front and sides. There shall be an integral trough at the rear of the hood to collect wash-down water.

9.2.9.5 Extreme care shall be used to avoid contamination of hoods, their work surfaces, duct work, and exhaust fans with perchloric acid.

9-3 Furniture .

9.3.1 Location.

9.3.1.1 The furniture shall be arranged such that exir from laboratory units may be reached easily from any point.


A9-2.9 A separate fume hood should be reserved for use with perchlori, acid. Such hoods should be labeled FOR PERCHLORIC ACID USEONLY Perchloric acid fume hoods should be washed down after each use. Consideratio! should begiven to continuous washing during use.

Chemic al Safety Data Sheet SD-t I, published by the Manufacturing Chemistl Association (see reference D12 in Appendix D), contains recommendations for th design and ventilation of perchloric acid fume hoods.

H A Z A R D I D E N T I F I C A T I O N 449 45=,15

Chapter 10 Hazard Identification

10-1 Facilities.

10-1.1 Signs at Entrances.

10-1.1.1 Entrances to laboratories, storage areas, and associ- ~lcd facilities shall have signs as necessary to warn emergency 0~efsonnel of unusual or severe hazards therein that are not directly aelnted to the fire hazard of the contents.

NOTE: Examples of severe or unusual hazards that inay require signs are unstable chemicals, radioactive chemicals, pathogenic materials, high iJowered lasers, and water-reactive chemicals.

10-2 Materials.

10-2.1 Labeling of Conta iners .

10-2.1.1 Containers, other than those being used in on- ~olng experiments, shall be identified as to their contents. Appropr i - ate identification shall include basic precaut ionary information. The identifying information shall be placed on the containers, tt0rage cabinet, storage space, or other accessible location.

10-2.1.2 Containers used for storage of peroxidizable compounds or materials that become hazardous upon prolonged storage ~hnil be dated when opened. Retent ion shall be limited to a maximum of six months after opening, and then containers shall be disposed of in a safe manner.

NOTE: The MCA Laboratory Waste Disposal Manual contains recommended methods of disposing of chemicals. (see referente D14 in Appendix D.)

450 45-4(; LABORATORIES USING CHEMICALS

A p p e n d i x B

Shockwaves from H e m i s p h e r i c a l Surface Explosions

Appendix B is not a purr of this ArFPA Standard. It is included for information purposes only.

Appendix B is in preparat ion and will be included when the Stand- ard is submit ted for official adoptioq.

A p p e n d i x C

E q u i p m e n t Inspec t ion , T e s t i n g a n d M a i n t e n a n c e

Appendix C is not a part of this .NFPA Standard. It is included for in. :formation purposes only.

Requirements for inspection, testing and maintenance of equipment will be found in the appropriate chapters of the Standard. See:

Automatic sprinkler sys tems- 4-2.2.4; Nonwater Automatic Extinguish. hag Systems-- 4.2.3.1 ; Standpipe Hose::- 4-3.4; Standpipe and Hose Sys tems- 4-3.5; Fire Alarm Sys tems- 4-5.2; Ventilation Equipment - 6-4.

Additional procedures are published in this Appendix C. Although not re. quired as a part of the standard, they are recommended for consideration as pan of a complete inspection, testing and maintenance program.

C1 Inspector's Qualifications. C1-1 For all inspections and tests described here, the inspector(s) should be

qualified by education or experience to utilize the required instruments.

C'2 Electrical Systems.

C2-1 Electrical system inspection and maintenance should be inspected a~ follows:

a. Grounding systems should be visually inspected and tested at leas! every two years to insure their continuity. C2-2 Conductive floors should be maintained and inspected as'follows: a. Waxes, polishes or dressings used on conductive floors should be electro. conductive. b. Conductive floors should be tested monthly in accordance with the Standard for the Use of Inhalation Anesthetics, NFPA No. 56A ~ 7973. C~-3 Standby and emergency power systems should be maintained and

inspected as follows: a. Generators for such systems should be activated wee.kly.

451 APPENDIX C 45--47

b. Attention should b e g i v e n to maintaining fresh crankcase oil and to maintaining fuel at an etlective level. I t is good practice to change crank- - case oil annually and to maintain the fuel tank above the three-quarter full mark.

NOTE: A guide to appropriate electrical system maintenance will be found in Handbook of Industrial Loss Prevention, Chapter 32, Electrical Maintenance. (see reference D16 in Appendix D.)

C5 Venti la t ion Equipment .

C5-1 Exhaust Ducts.

C3-1.1 Exhaust duct internal inspecdous should be performed at least t0nually and accumulations of dust or chemicals that present a potential fire- tpread or explosion hazard should be removed promptly.

C3-1.2 Duct access doors should be labeled to warn of the type of hazard qhat might be present, e.g., flammable vapors, combustible dusts, perchloric ~ id , and the precautions required before work is begun.

C3-2 Fire Dampers.

C.%2.1 Fire dampers should be inspected for proper operation annually.

C3-2.2 An effective procedure for the inspection of fire dampers follows:

(a) Warn users of systems that air flow will be interrupted briefly.

(b) Disconnect fusible link and allow damper to close completely while the ventilation system is functioning under normal flow conditions.

(c) Check the damper, the fusible link, and its wire or chain connector for corrosion or deposits which might cause them to release accidentally. Also check fusible link temperature rating for proper application.

(d) Repair or replace any malfuntioning or improper part.

C3-3 Filters.

C3-3.1 Filters for air supply and /o r exhaust should be inspected at least tfmiannually and cleaned or replaced as required to prevent accumulation of Cotnbustible or hazardous particulate matermls.

C3-3.2 Exhaust system filters should be renewed when spent or when ap- opriate to prevent accumulation of incompatible materials particularly when )oratory activity or chemicals to be used are changed.

C3-3.3 Air scrubbers for removal of fumes, gas, vapor, mist or com- ~ t i b l e particulate matter should be inspected at least annually to ascertain {~t~tt they are performing in accordance with design or manufacturer 's speci- (~f~t tious.

C3-4 Emergency Operation of Exhaust Systems.

C3-4.1 Emergency power systems installed on critical exhaust ven- (J~tion systems should be tested for automatic cut-in at least quarterly.

C3-5 Spray Booths.

C&-5.1 Spray booth interiors, including filters and exhaust ducts should Inspected frequently and overspray deposits should be removed as required.

NOTE: Easily removable coatings or liners facilitate frequent removal of deposits from booth interiors.

452 45--48 LABORATORIES USING CHE.MICALS

Appendix D References

Appendix D is not a part of this ArFPA Standard. It is included for in. formation purposes only.

DI ASTM Standard D56-70, Standard Method of Test for Flash Point by Tag Closed Tester, American Society for Testing and Material, 1916 Race Street, Philadelphia, PA 19103.

D2 Structures to Resist the Effects of Aeeide,~tal Explosions, Department of the Army (TM 5-1300), Navy (NAVFAC-P397), and Airforce (AFM 88-22), Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402, June 1969.

D5 Dobbs, N., Dede, M. and Rindner, R., New Concepts in the Design of Structures to Resist the Effects of Explosive- Toxic Detonations, Dover, NJ 07801, Picatinny Arsenal, May 1970.

D4 Industrial Hygiene Practices Guide: Laboratory Hood Ventilation, American Industrial Hygiene Association .|ouroal, November-December, 1968, pp. 611-617.

D5 Committee on Industrial Ventilation, Industrial Ventilation: A Manual of Recommended Practice, Committee on Industrial Ventilation, American Conference of Governmental Industrial Hygienists, P.O. Box 453, Lansing, M! 48902. Twelfth Edition, 1972.

D6 ASTM Standard E162-67, Standard Method of Test for Surface Flare. inability of Materials Using A Radiant Heat Energy Source, American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.

D7 ANSI Standard B31.1.0--1967, B31.1.0a--1971 (Second Edition), B31.1.0b- 1971, B31.1.0c- 1972 and B31.1.0d- 1972, Power Piping with Addenda, American National Standards Institute, 1430 Broadway, New York s NY 10018.

D8 ANSI Standard B 3 1 . 2 - 1966, Fuel Gas Piping, American Nationel Standards Institute, 1430 Broadway, New York, NY 10018.

D9 ANSI Standard B31.3--1966, Petroleum Refinery Piping, American National Standards Institute, 1430 Broadway, New York, NY 10018.

DI0 ANSI Standard A13.1 - - 1956, Standard Scheme for the Identifieati~ of Piping Systems, American National Standards Institute, 1430 Broadway~ New York, NY 10018.

D l l CGA Standard P-I, Fifth Edition, 1965, Safe Handling of Compre~r Gases, Compressed Gas Association, 500 Fifth Avenue, New York, NY 100M

DI2 MCA SD-1 through SD-98, Chemical Safety Data Sheets, 1947-197| Manufacturing Chemists' Association, 1925 Connecticut Avenue, N.W Washington, DC 20009.

DIS ASME Boiler and Pressure Vessel Code, Press. ure Vessels, Section VII Rules for Construction of Pressure Vessels, Division 1, 1971 Edition, Americt Society of Mechanical Engineers, United Engineering Center, 345 East 47,

453 APPENDIC 45-49

DI4 MCA Safety and Fire Protection Committee, Laboratory Waste Dis- ,~nal Manual, November 1972, Manufacturing Chemists' Association, 1825

necticut Avenue, N.W., Washington, DC 20009.

DIS ASTM Standard D93-72, Test for Flash Point by Pensky-Marteus filmed Tester, American Society for Testing and Materials, 1916 Race Street, Vhiladelphia, PA 19103.

D16 Factory Mutual Enl~ineering Corporation, Handbook of Industrial 0~las Prevention, Second Edition, 1967, McGraw-Hill Book Company, Chapter

DI7 Allen, D.S. and Athens, P., Influence of Exvlosion on Design, Loss Prevention Manual, Voi. 2, American Institute of C[~emicai Engineers, New York, 1968.

DI8 Brasie, W. C. and Simpson, D. W., Guidelines for Estimating Explosion 0~amage, ~ Prevention Mamml, .Vol. 2, American Institute of Chemical ~t~l]ineers, New York, 1968.

DI.9 Norris, C.H., Hansen, R.J., Holley, M.J.,.Jr., Briggs, J.M., Namyct, S.j *t~! Minami, J.V., Structural Design for Dynamic Loads, New York, McGraw- 01ill Book Company, 1959.

D20 Cohen, E., Editor, Prevention of and Protection Against Accidental ~plosion of Munitions, Fuels and Other Hazardous Mixtures, Annals of (.'~ New York Academy of Sciences, Vol. 152, Article 1, 1968.

021 Newmark, N.M., An Engineering Approach to Blast Resistant Design, .~',0lerican Society of Civil Engineers, Transaction 121, 1956.

' 022 Brinkley, S.R., Determination of Explosion Yields, Loss Prevention ~|lltmal, Vol. 3, American Institute of Chemical Engineers, New York, 1969.

02.~ Kinney, G.F., Explosive Shocks in Air, New York, The MacMillan 6 ~npany, 1962.

024 .JANNAF Propulsion Committee, Chemical Rocket/Propellant Haz- 4::~t Vol. 1, General Safety Engineering Design Criteria, Silver Springs, Mary~ ~t~.~t, Chemical Propulsion Information Agency, 1971.

025 Lawrence, W.E., and Johnson, E.g., Design for Limiting Explosion ~ ~A:nage, Chemical Engineering, Vol. 81, No. 1, January 7, 1974, pps. 96-104.

454 REVISIONS TO NFPA NO. 43A 43A-I

Part Ill

Proposed Amendments of

Code for the Storage of Liquid and Solid Oxidizing Materials

NFPA No. 4 5 A ~ 1975

I. In Table 121, place after the Calcium Hypochlorite entry in Class ;'(except as provided under Class 2)."

2. In Table 121, add to the Class 1 oxidizers the following: Sodium Persulfate, Ammonium Persulfate, Sodium Perborate Tetrahydrate, and Sodium Carbonate Peroxide.

3. In Table 121, change the Class I oxidizer Sodium PerboTate to Sodium Perborate Monoh.ydrate.

4. In Table 12T delete potassium dichlovoisocyanuTate as a synonym foe the Class 3 oxidizer Mono-(trichloro) tetra-(monopotassium dichloro), penta-s-triazinetrione.

5. In the definition ~ Class 1 oxidizer change "i t increases the burnin 8 rate" to " i t may increase the burning rate," the revised definition t~ read: "An oxidizing material whose primfiry hazard is that it maF increase the burning rate of combustible material with which {! come8 in c o n t a c t . "

6. Add to 241: "or to 120~ whichever is lower."

7. In 462 delete the reference to NFPA No. 80A, the revised 462 to read "To be considered detached a nonsprinklered building for storage of Class 2 oxidizers shall be located no less than 50 feet from otht~ buildings or a line of property which may be built upon."

43A-2 C O M M I T T E E O N Ct lEMICAI . ,S A N D E X P L O S I V E S 455

O, in 562 delete the reJerence to ArFPA Aro. 80A, the revised 562 to read: r be considered detached a nonsprinldered building for storage f:~ Class 3 oxidizers shall be located no less than 75 feet from other r or a line of property which may be built upon."

Include in the definition.of detached storage, storage in the open, the n4:ited definition to read: "Storage, either in the open or in a separate I';~l[Iding, located away from all structures except those housing ~ra t ions related directly to the production of the stored materials."

O0, In Table 121, add to the Class 1 oxidizers the following: "Sodium D}~chloro-s-triazinetrione Dihydrate."

456 ADMINISTRATION, SCOPE, DEFINITIONS 43D-~

Part IV

Proposed Tentative Code for

Storage of Pesticides in Portable Containers

NFPA No. 4 3 D - T ~ 1974

C hap t e r 1 Adminis t ra t ion

1-1 Scope.

1-1.1 This standard shall al~ply to both inside and outsidf storage of all forms of pesticides in portable containers other tha~ fixed installations on transportation equipment.

1-1.2 Storage in individual containers larger than 660 ga| Ions is not within the scope of this standard.

1-1.3 This standard shall not apply to noncommercial storag~ of pesticides in households and garages for use around the home.

1-2 Definltions.

1-2.1 The following terms, will for the purpose of this Codt have the meanings indicated below.

Basement shall mean a story, of a building or a structurf having one-half or more of its height below ground level a~3 to which access for fire fighting purposes is unduly restrict~

Commercia l User shall mean a person, such as a commerr grower, a custom applicator, a pest control operator, a fumigat~ or a greenhouse operator, who stores pesticides for his own in a storage building or storage area to which the public or~l narily does not have access.

Closed Conta iner shall mean a container as herein defiaC~q so sealed by means of a lid, closure, valve, adhesive closure, 0 other device that liquid, vapor, or dusts do not escape from N under ordinary conditions of use or handling.

Conta iner shall mean any bag, bottle., carton,,can, pressuritl container, drum, portable tank, or other closed vessel contain1:t a pesticide prepared for distribution or storage.

o, 4 5 7

I l lgh ly Toxic Pesticide shall mean any pesticide which is UC{luired by law to bear a skull-and-crossbones and be labeled t~lth the word POISON.

Mercant i le Occupancy shall mean the occupancy or use of a ~milding or structure or any portion thereof for the display and ~le of pesticides at retail.

Person shall mean any individual, partnership, association, ~htciary, corporation, or any organized group of persons, e~hether incorporated or not.

Pesticide shall mean (a) any substance or mixture of substances b3tended for preventing, destroying, repelling, or mitigating any ~?JI, (b) any substance or mixture of substances intended for

as a plant regulator, defoliant, or desiccant.

Warehouse shall mean any building or structure or portion {~ereof used for storage of containers of pesticides and shall l,~lude areas where finished stock is being held temporarily in a ~ n u f a c t u r i n g area.

Secure means safe from intrusion, or placarded separately to ~J lea te the presence of highly toxic pesticides.

Segregated shall mean storage in the same room, but physically r by space, from other materials.

4 5 8 43D: GENERAL REQUIREMENTS

Chapter 2 General Requirements

2-1 Bui lding Location.

2-1.1 Unless exempted by the authority having jurisdieti0;~ pesticide storages shall be located or constructed so that runoff fro; fire-fighting operations will not contaminate streams, pond~ groundwaters, croplands, pasture land, or other buildings.

NOTE: Appendix A contains recommendations for choosing the site for a pesticide storage building.

2-2 Fire Protection.

2-2.1 Unsprinklered storage facilities shall be in aceordan{,~ with the pertinent sections of this standard. Sprinldered ind0~,. storage facilities shall be in accordance with the Standard for Ind,. Storage, AfFPA Afo. 237 - - 7972. Outdoor storage shall be in e~ cordanee with Recommended Safe Practices for Outdoor General Stor~, AfFPA aVo. 231A - - 1970.

2-3 Storage of Flammable and, Combustible Liquids.

2-3.1 Unless otherwise specified herein, pesticides that flammable liquids or combustible liquids shall also be stored t accordance with the pertinent sections of the Flammable and ~.,~ bustible Liquids Code, aVFPA No. 30 - - 1973, and Standard for (' Storage of Flammable and Combustible Liquids on Farms and lsol~ Construction Projects, aVFPA No. 392 ~ 797Z

NOTE: Flammable liquids and combustible liquids are defined in tht Flammable and Combustible Liquids Code, NFPA No. 3 0 - 1973.

2-4 Storage of Oxidizing Agents.

2-4.1 Pesticides that are oxidizing agents shall also be st0~; in accordance with the Code for the Storage of Liquid and Solid Oxidlt~, Materials, jVFPA aVo. 43,4 ~ 7974.

2-5 Ammonium Nitrate.

2-5.1 Pesticides shall not be stored in the same facility ~', ammonium nitrate fertilizer.

Exception: Pesticides may be stored in the same facility with ammoS; nitrate fertilizer i f the fertilizer is stored in accordance with the Code~ the Storage of Ammonium Nitrate, AfFPA No. 490 - - 1970.

,t~l)-8 STORAGE OF PESTICIDES IN PORTABLE CONTAINEIt~4 459

Separation of Pesticides.

2-6.1 Pesticides in storage shall be stored together in ac- I ~'dance with good pesticide storage practice and adequately ~v~|eegated from other materials in storage.

~OTE: Good pesticide storage practice may require that different types (~' pesticides, such as insecticides and herbicides, be separated to prevent (~ontaminat ion.

~.7 Signs.

2-7.1 Pesticide storage buildings, storage rooms, or storage �9 ~;f0s shall be identified by prominent and legible signs so posted ,~) to give notice of the presence of pesticides.

2-7.1.1 Identification signs shall be of durable material ,~ "~j display the word PESTICIDES in ultra-bold uncondensed ()'0)|an capitals at least two inches actual height, in black printing : ) white background, surrounded by a quarter-inch black border.

2-7.1.2 When a highly toxic pesticide is present, the word ~x)ISON and the skull-and-crossbones, set forth as specified in ~ '~|.! shall be added.

~-0 Visibility of Labels.

2-8.1 In each pile, bin, bay, rack, or other grouping of pesti- t~,~ containers, enough containers shall have labels visible to per-

': ,3 ready identification from all ordinary avenues of approach.

Leakage of Containers.

~9.1 Leaking or severely damaged containers of pesticides, ~ (~gtterials contaminated by pesticides, shall be segregated. Dis-

'Lql 0hall be in accordance with regulatory requirements, manu- I ~ ::c~,~l)'er's instructions, or recommended industry practice.

~10 Management of Post-fire Problems.

~10.1 Written procedures for management of post-fire prob- ;) thflli be available.

~11 Basement Storage.

~ l l . l If basement storage is used, adequate provision shall * ~.~dc for containment or treatment of fire-fighting water runoff. ~ dlo Appendix A, Recommendations for Pesticide Storage Facilities.)

~ t l d i x B contains recommendations for post-fire procedure.

460 STORAGE FACILITIES 43D-9

C h a p t e r 3 S to r age Fac i l i t i e s

3-1 Storage in Warehouses.

3-1.1 Storage Arrangement.

3-1.1.1 Where f l ammable or combus t ib le pesticides art stored, pile size shall be l imi ted by means of aisles to a size which permi ts r eady access for m a n u a l fire fighting.

3-1.1.2 Storage of e m p t y combust ib le pallets in unsprin, k lered s torage areas shall be in accordance with 3-1.1.1, and in n0 case shall a pile of pal lets be more than six feet high or cover mort than 200 square feet of floor.

3-1.2 F i r e Protection.

3-1.2.1 Genera l fire protec t ion shall be in accordance with a p p r o p r i a t e N F P A s tandards .

NOTE: Appropriate NFPA Standards include 'Standard for the lnstalla. tion of Portable Fire Extinguishers,' NFPA No. 10 - - 1973; 'Standard for the Installation of Spril~kler Systems,' NFPA No. 13 - - 1973; 'Standard for the Installation of Centrifugal Fire Pumps,' NFPA No. 20 - - 1971; 'Standard for the Installation of Standpipe and Hose Systems,' NFPA No. 14 - - 1973.

3-1"2"2 Emergency p rep lann ing shall be established. ~

3-1.3 B u i l d i n g M a i n t e n a n c e O p e r a t i o n s .

3-1.3.1 Bui lding olSerations, inc luding waste disposal, sm0~ ing, main tenance , inspection, and emergency access shall be in 8~ cordance with Art ic le 2-9 of this s t anda rd and with the Staad#;, for Indoor General Storage, .ArFPA No. 231 - - 1972, Chapter 6, Buildlt# Maintenance and Operations. ~

2Appendix C contains recommendations for emergency planning.

43D-10 461

STORAGE OF PESTICIDES IN PORTABLE CONTAINERS

$-2 Storage in Mercant i le Occupancies.

5-2.1 Segregation of Pesticides.

5-2.1.1 In retail establishments such as supermarkets, food 4aOreS, or variety stores, pesticide display and storage shall be segre- Gated from displays or stocks of materials such as food, feed, and (~0thing, which are intended for human or animal use or con- 4~0mption.

5-2.2 Quantif ies on Display.

5-2.2.1 In rooms or areas accessible to the public, quantifies I ~ pesticides shall be limited to those needed for display and normal I i~fchandising purposes.

5-2.3 Method of Storage.

3-2.3.1 Drums and large packages shall be stacked se- gfely or placed on fixed shelving.

5-2.3.2 Shelving shall be of stable, sturdy construction, of ~}]cient depth and arrangement that containers stored or dis- I~yed thereon cannot be easily displaced.

$-2.4 Leaking Containers.

5-2.4.1 Leaking containers shall be removed immediately (~,~0 the display area and disposed of in accordance with 2-9.1.

Inside Storage by Commercial Users.

$-5.1 Pesticide Storage Area.

5-3.1.1 A separate building, room or portion of a building .(,~ ell be designated as the "Pesticide Storage Area. ''8

5-3,1.2 The "Pesticide Storage Area" shall have walls or i,'.~tltlons to separate it from occupancies other than storage, i.e., '. '~CS or retail areas, in the same structure.

r A contains recommendations for pesticides storage facilities.

462 STORAGE FACILITIES 43D-I i

3-3.1.3 The "Pesticide Storage Area" shall be illuminate~ as necessary to allow ready identification of pesticide container1;

3-3.1.4 The storage temperature shall be above 35~ and below 125~ or as otherwise directed by the-manufacturer.

3-3.2 Method of Storage.

3-3.2.1 Pesticides shall be stored so as to prevent deleterimlt contact with moisture.

3-3.2.2 The storage area shall be closed and locked when it is not supervised by a responsible person. The public and animal! shall be excluded.

3-3.3 Fumigants Stored as Compressed Gases.

3-3.3.1 Compressed gas fumigants shall be stored away from heat (steam pipes, heaters and direct sun).

3-3.3.2 Containers shall be handled to avoid shock as from dropping, bumping, dragging or sliding and shall be secured to prevent toppling during storage, transportation or discharge.

3-3.2.3 Containers shall be tightly closed and provided with a safety cap when not in use, whether empty or full.

3-3.2.4 Containers shall be'segregated one type from another and from other compressed gases by pipe railings or other effective means.

,e,t)-12 _=

463 S T O R A G E O F P E S T I C I D E S I N P O R T A B L E C O N T A I N E l l 8

APPENDIX A.

Recommendations for Pesticide Storage Facilities

'this Appendix is not a part of this Standard. It is included for information purposeJ"

~ l General Recommendations.

(l) For indoor storage areas, install sprinkler protection in ac- f4~rdance with the Standard for Indoor General Storage, N F P A No. ~JI ~ 1972,

(2) In a multistorage facility, use a first-floor corner room with direct outside access. A separate building is preferable, however.

(3) Because of the difficulty of fighdng fires, of salvage and de- ~0ntamination, and of controlling runoff, do not store pesticides Bt basements.

(4) Store highly toxic pesticides (those bearing the word POISON 0nd the skull-and-crossbones on the container label or the shipping (~e) in a properly controlled, secure, and supervised area. Local regulations may require secured (locked) storage. Post the room or "Gtbinet with a sign displaying the word POISON and the skull- and-crossbones in the style described in 2-7~1.2.

(5) Do not store pesticides in the same area with, adjacent to, Or directly above feeds or livestock, or near fire hazards such as tmmonium nitrate.

(6) Ensure drainage away from the" storage building, but mini- fllize runoff to sensitive areas. Where necessary, use containment facilities such as natural barriers, holding ponds, or dikes.

(7) Insofar as possible, store pesticides to be used by com- gnercial users in a noncombustible building with an impervious floor.

A-2 Existing Buildings.

(1) Use a separate building if possible. (2) If separate buildings cannot be used, choose a wing or

corner, preferably on the first floor, with direct outside access to facilitate escape and fire-fighting in case of fire.

A-$ New Buildings.

(1) Choose the location carefully. (2) Check the prevailing wind. If possible, locate downwind

from and be isolated from nearby residences.

4 6 4 APPENDIX B 43D-18 I

(3) Choose an area separate from livestock, forage and feed storage, and other fire hazards.

(4) Choose an area such that natural runoff water from storage area, or seepage through soil, or runoff from fire-fighting, will not contaminate residential areas, livestock feeding areas, streams, or ponds.

(5) Follow pertinent General Recommendations in A-I above.

APPENDIX B.

Recommendations for Post-F/re Procedures

This Appendix is not a part of this Standard. It is included for information pu~posO only.

The following procedure is recommended for effective management of post-fire problems:

lb l Personal Precautions.

(1) Wash, shower, and shampoo thoroughly, as soon as possibleq using large volumes of soap and water to remove any traces of toxic chemicals.

(2) Put on clean clothes. (3) If leather or leather-soled shoes were worn, check them f0t

absorbed pesticides, and if suspected of being contaminated, discard, (4) Wash all personal clothing, protective clothing and breath,

hag apparatus. Do not contaminate inside of breathing apparatuj from chemicals deposited on outside. Clean protective clothir~ will be needed each day of the post-f/re activity.

(5) Bc on the lookout for any symptoms of pesticide poisonins~ They may show up immediately or not for several hours.

B-2 General Rules for Salvage and Decontamination.

(I) Notify local public health officials. (2) Post warning signs and rope off to prevent unauthorize~

entry to burned out area and water runoff area. 0) Check with manufacturers for additional advice and for u~

of expert decontamination team if available. (4) Have a person familiar with pesticides direct cleanup ol~

eration. (5) Wear protective clothing, including self-contained brcadt

ing apparatus. Boots, gloves, and chemical workers' goggles a~ important since some pesticides arc absorbed directly through th~ skin and eves.

43D-14 465 STORAGE OF PESTICIDES IN P O R T A B L E CONTAINER~

(6) Do not smoke, eat, or drink in the area, or before washing.

(7) Be careful not to track pesticides out of the area.

8-3 Procedure for Decontaminat ion and Disposal.

(1) Neutralize and absorb toxic chemicals.

(a) Obtain recommended neutralization and absorption procedures from manufacturer.

(b) Neutralize runoff water. Pump standing water into disposal tankers.

(c) Arrange for disposal of waste water with local authorities.

(2) Use safe removal procedures.

(a) Be sure all personnel involved understand toxic nature of debris, and are properly clothed and masked.

(b) Use mechanized loaders, dump trucks, etc. to minimize human contact with contaminated material, unless the presence of flammable liquids is suspected.

(c) Avoid raising a dust.

(d) Absorb excess liquid with lime, sawdust, or clay, or as recommended by manufacturer. Do not wash any material into a waterway or sewer system without official authorization of public health official.

(e) Carry debris to an approved dumping area in tight metal, bodied dump trucks or tight containers. Moisten, or cover load with disposable cover if dust is a problem. Avoid overloading so that no spills will occur en route.

(f) Scrape as necessary grounds or ditch banks contaminated with runoff water to remove contaminants. Dispose of scrapings with the rest of the debris.

(g) Treat spills from leaking containers found during cleanup in accordance with manufacturer's instructions.

(h) Decontaminate tools, vehicles, concrete slabs, etc., using an appropriate solution; scrub thoroughly and follow with a clean water rime. Destroy pallets and drainage materials contaminated by leaking containers.

(i) Inspect and test the surrounding area for possible contamination and leave entire area safe for public and in usable condition.

(3) Use safe disposal procedures as specified by appropriate ,~Jthorities.

466 APPENDIX C 4 3 D - I ~

APPENDIX C.

Recommendations for Emergency Planning

This Appendix is not a part of this Standard. It is included for information purp~lj only.

Provisions contained herein are for information and recommende~ as good practice. Information for specific pesticides should be ob tained from the manufacturer.

0.1 Informing Emergency Organizations.

(1) Inform local fire department and police of location and la~'~ out of storage, types of material stored and hazards involved. At, range for nonworking hours contact, including an emergency phozW number for the person responsible for storage.

(2) Inform local hospitals and poison control centers of potemll'l hazards. Be sure they know how to treat potential illnesses ass0 ciated with fires containing pesticides. Antidotes and treatment~ may be obtained from manufacturers or from "Clinical Handb0~ on Economic Poisons. ''4

(3) Have manufacturer provide recommended procedure f~ detoxification of spills.

O-2 Fire Department Preplanning.

(1) Provide for protection of employees and local residents

(a) Evacuate residents who are downwind of fire. (b) Prevent unauthorized entry to fire area. (c) Have a medical check made of employees that may hav~

been exposed to fumes or other contamination of peril cides.

4W. J. Hayes, Jr., Clinical Handbook of Economic Poisons, 1963, Gonur::, pie.able Diseases Center, Atlanta, Georgia. Order from National Techniu~ Information Service, Operations Division, Department A, Springfield, Virg[~. 22151. NTIS Order Number: PB-218-287.

43D-16 467

S T O R A G E O F P E S T I C I D E S I N P O R T A B L E C O N T A I N E R S

0-5 Notify local fire author/ties that firemen should:

(a) Wear protective clothing over the entire body including gl0bber boots, gloves, hat, and coat and avoid contact with toxic ~gqltes or smoke. Self-contained breathing equipment (air packs) is r for those exposed to fumes or smoke.

(b) Be immediately relieved from duty and checked for possible (,~olsoning if exposed to fumes or smoke without adequate protection.

(c) Wash thoroughly and immediately with large volumes of ~.gtp and water if contacted by pesticides. Any person heavily ~Hlosed to pesticides should be examined by a physician immedi- *lely without waiting for symptoms to occur.

(d) Be alert for symptoms of poisoning during the fire. Symp- C~)ms may include headaches, giddiness, blurred vision, coughing, r of chest, salivation, twitching, or pinpoint eye pupils. .~*ymptoms of pesticide poisoning may be mistaken for heat ex- 1~2lustion or smoke inhalation.

(e) Avoid smoking, drinking, or eating while fire fighting so as (.'or to ingest toxic substances.

468 ADMINISTRATION 43C~/I

Part V

Proposed Tentative Code for the

Storage of Gaseous Oxidizing Materials

NFPA No. 43C-T-- 1974

Chapter 1. Adminis t ra t ion

1-1 Purpose. 1-1.2 The purpose of this Code is to outline the basic principlo

and procedures for protection against fires and explosions durin 8 the storage of gaseous oxidizing materials in cylinders, tanks, and other containers.

1-1.3 The provisions of this Code are intended to reduce the hazards from the storage of gaseous oxidizing materials, but com. pliance with the Code will not eliminate all hazards in their use.

NOTE: Gaseous oxidizing materials are generally irritating, toxic and highly reactive chemically. They can react violently with finely divided metals and with organic and other materials that are readily oxidizable.

1-2 Scope.

1-2.1 This Code shall apply to the storage of oxidizing ma. terials that are gases at ambient temperatures, or are liquids havin 8 a vapor pressure exceeding 40 pounds per square inch (absolute) nl 100 ~ F and that are ordinarily stored in metal cylinders, containers or tanks.

NOTE: Table 1-2.1a lists several commercially available gaseous oxidizing agents. Table l-2.1b lists examples of gaseous oxidizing agents not readily available.

1-2.2 The Code shall apply to oxidizers in cylinders or other containers in excess of 100-pound capacity when in storage and when connected to a manifold system from which the gases may Be piped.

1-2.3 I t shall not apply to solid or liquid oxidizing agents, which are covered by NFPA No. 43,4 ~ 1974, Code for Storage o.I Liquid and Solid Oxidizing Materials.

1-2.4 I t shall not apply to the storage and handling of oxygen to the extent covered by ArFPA Aro. 50--1973, Standard for Bulk

S T O R A G E O F G A S E O U S O X I D I Z I N G M A T E R I A L S 469

('Og'gen Systems at Consumer Sites; .NFPA .No. 51--1973, Standard for t,'~ Installation and Operation of Oxygen-Fuel Gas Systems for Welding and (,~fting; .NFPA .No. 5 6 B - 1973, Standard for Respiratory Therapy; ,~'FPA .No. 56F--1973, Standard for .Nonflammable Medical Gas Sys-

I-3 Definitions

1-3.1 The following terms, for the purpose of this Code, will [~ve the meanings given below.

Ghemical Reactivi ty shall mean the property of reacting (C'~micalIy with other material, including water;

Haza rd Rat ing shall mean the numerical rating of the health, ~Alnmability and self-reactivity hazards of the material, including I~ reaction with water, as defined in .NFPA .No. 7 0 4 M - 1969, (~r System for the Identification of the Fire Hazards of Materials;

Incompatible Materials shall mean those materials that, when ~.~lxed with oxidizing materials, can cause hazardous reactions or ~n catalyze decomposition of the oxidizer;

Oxidizing Material shall mean any material that readily yields wgen or other oxidizing gas or that reacts chemically to oxidize

(ombustible materials;

Storage:

Segregated Storage shall mean in the same room, but phys- ~.~lly. separated by space from incompatible materials and com- ~l~t:ble materials.

Cutoff Storage shah mean storage in the same building with ~,|her materials but physically separated from incompatible ma- ~2r and combustible materials by walls having a fire resistance O~llng of at least one hour.

Detached Storage shall mean storage either in the open or t,1 a separate building of noncombustible construction located sway from all structures except those housing operations related r162162 to the production of the stored materials.

470 GENERAL .REQUIREMENTS 43(~

Chapter 2. General Requirements

2-1 Identification of Materials in Storage.

2-1.1 All storage areas shall be conspicuously identified with sign " D a n g e r - - G a s e o u s Oxidizers" and by their hazard idenl~ fication in accordance with the AtFPA aVo. 704M - - 1969, Reco~ mended System for the Identification of the Fire Hazards of Materials.

Exception. When only one oxidizer is present, the sign may be modified t~ read "Danger - - (Chemical .Name) '' plus hazard identification.

2-1.1.1 When materials having different hazard identifir tions are stored in the same areas, the area shall be marked I',~ indicate the mosc severe health, flammability, and reactivity hat ards in the area.

NOTE: For hazard ratings of many gaseous oxidizing materials see NFPA No. 49 ~ 1973, Hazardous Chemicals Data, and NFPA No. 325M - - 1969, Fit# Hazard Properties of Flammable Liquids, Gases, and Volatile Solids.

2-1.2 When hazard identification numbers for a material haw not been published in ~fFPA No. 4 9 - - 1973, Hazardous Chemic~'J Data, or in .~fFPA No. 3 2 5 3 4 - 1969, Fire Hazard Properties of Flat~: mable Liquids, Gases and Volatile Solids, identification numbers may br assigned by comparison of the known health, flammability and sel| reactivity properties of the gaseous oxidizers with those of a gasco~b oxidizer to which hazard identification numbers have been assigned

2-1-3 All cylinders and other containers shall be individuall~ marked with the chemical name of the gaseous oxidizer.

2-2 Employee Instruction.

2-2.1" Personnel involved in areas where gaseous oxidizers arc stored shall receive instructions in methods for the safe handlin~ of cylinders or other containers and in emergeni=y procedures.

*An asterisk beside a number indicates that Appendix A contains relat~ information.

Append~ A ,

Appendix A, which starts here and continues at the foot of other pages o~ the Code ca necessary, is not a part of the Code and is included for information purposes only.

A2-2.1 Employees should not work alone when connecting or disconnect, ing cylinders or other containers.

t~%8 S T O R A G E O F G A S E O U S O X I D I Z I N G M A T E R I A L , q 47i

2-2.1.1 Training shall include the use of respiratory and <;~her personal protective equipment, drills on alarm and evacuation (,~0r the handling of leaks, and plans for protection in case ~ fire in adjacent areas.

2-2.2* Alerting procedures giving the names and the tele- ~t0ne numbers of individuals who shall be notified in case of a leak C~ accident shall be posted outside of the storage area.

2-2.3 Appropriate protective equipment including approved r protective equipment shall be readily available outside <r the storage area.

2-5 Hea t ing

2-3.1 Storage areas shall be arranged so that stored cylinders 0r other containers cannot be heated above the ambient tempera- Itlre of the storage area.

2-3.2 Cylinders or other containers shall not be subjected to direct heating to increase vapor pressure.

2-4 Main tenance a nd Repairs

2-4.1 The performance of maintenance work in the storage area : 0,td immediate surroundings shall be subject to prior review and approval by supervisory personnel.

2-4.2 Cutting and welding procedures shall be in conformance with JVFPA .No. 5 1 B - - 1971, Standard for Fire Prevention in Use of ~'ulting and Welding Processes.

2-5 Fire Protection

2-5.1 Water supplies and fire hydrants, as required by the t~uthority having jurisdiction, shall be installed in accordance with ~FPA .No. 2 4 - - 1973, Standard for Outside Protection.

2-,5.2 Automatic sprinkler protection shall be provided for combustible buildings containing gaseous oxidizer storage.

2-5.3 Automatic sprinkler protection shall be provided in noncombustible buildings when there is combustible material within 50 feet of segregated storage of gaseous oxidizers.

Appendix A - - cont.

A2-2.2 It would be advisable to include the name and the telephone number of the manufacturer or the supplier of the gases.

472 GENERAL REQUIREMENTS 430.o

2-5.4 Small hose or portable extinguishers suitable for Class A fires, shMl be provided throughout the storage area. Extinguishers suitable for Class B and Class C fires shall be provided as needed.

2-5.5 Portable extinguishers shall be installed in accordance with aVFPA aVo. ?0 - - 1973, Standard Jor the Installation oJ Portable Fire Extinguishers. Small hose shall be installed in accordance with ArFPA .No. 14 ~ 1973, Standard for the Installation of Standpipe and Hose Systems.

2-6 Housekeeping

2-6.1 Combustible materials shall not be allowed to ac- cumulate within 20 feet of gaseous oxidizer storage.

2-6.2 Dry grass and weeds shall be removed from outdoor storage areas and combustible trash shall be prevented from ae. cumulating.

2-7 Exits

2-7.1 Each storage area shall have at least two means of exit remote from each other unless otherwise approved by the authority having jurisdiction.

2-7.1.1 Doors shall open outward.

2-8 Ventilation.

2-8.1 Positive exhaust ventilation shall be provided for an enclosed storage area. Natural ventilation is adequate for open storage areas.

43.C--I0 S T O R A G E OF G A S E O U S O X I D I Z I N G M A T E R I A L S 473

Chapter 3. Storage Facilities

3-1 Storage Areas

3-1.1 Gaseous oxidizing agents shall be stored in segregated, CUtoff, or detached storage areas.

3.1.2 Basements and other subsurface areas shall not be used.

3-1.3 Cylinders and other containers shall not be stored near f|evators, ventilating systems or other openings through which gas r spread to other parts of a building if a leak occurs.

3-1.4 Detached storage shall be located at least 20 feet from e~0ncombustible buildings and 50 feet from combustible buildings or Combustible yard storage.

$.2 Cyl inders and O the r Containers .

3-2.1 Cylinders and other containers stored outdoors shall be r off the ground on a raised concrete pad or noncombustible ~ck.

3-2.2 Cylinders and other containers shall not be stored where ~ey. can drop, where heavy objects can fall on them, or where

�9 schlcles can strike them.

3-2.3 Cylinders shall be stored upright.

3-2.3.1 Racks or other means shall be provided to hold them ,~'~urely.

3-2.3.2 Valve caps shall be kept in place except when ~.~4[nders are in use.

3-2.4 Ton containers shall be stored on the side following the ( L~nufacturer's recommendations.

3-2.5 Empty cylinders and other containers may be stored in I '~ eame area if separated from full cylinders and containers.

3-2.6 Cylinders and other portable containers shall be stored "~ it manner to permit ready inspection and shall be arranged for

6~r0mpt removal in case of a leak.

$-2.7 Cylinders and other containers shall be inspected peri- t]~r for corrosion and leaks.

$-2.8 Suitable equipment shall be available for moving cyl- Y~lers and other portable containers.

3-2.8.1 Hand trucks shall be equipped with a clamp or I~in to secure the container in place.

474 STORAGE FACILITIES 45C"11

Table 1-2.1a

Gaseous Oxidizing Materials - - Commercially Available

Boiling Density Reactivity Hazard Name Formula Point (~ ( A i r = l ) with Water Radngs*

Chlorine CA s -- 34 2.4 Slow 3-0-0

Chlorine Dioxide ClOs 10 Slow (4-0-4)

Chlorine Trifluoride CAFa 11.8 3.2 Violent (4-0-3)

Fluorine Fs --188 1.3 Rapid 4-0-3

Nitrogen Tetroxide N,O4 --151 3.2 Slow 3-0-0

Nitrogen Trioxide NsOa 3.5 2.6 Slow (3-0-0) Oxygen Os -- 183 1.1 No (0-0-0)

*Hazard ratings in parentheses are temporary assignments.

Table 1-2.1b

Gaseous Oxidizing Materials - - Not Readily Available

Boiling Density Reactivity Hazar~ Name Formula Point(~ ( A i r = l ) with Water Ratingty

Chlorine Mono- fluoride O F --101 1.9 Violent (4-0-}}

Chlorine Monoxide Cl iO 3.8 3.0 Soluble (4-0-0)

Chlorodifluoroamine CANFs --67 3.0 Reacts

Chlorine Tetroxide CI,08 Decomp. . at --105

Difluorodiazine NsFt --111.7 2.2 Does not r e a c t (-0.0~)

Difluoroamine HNF= --23.6 1.8

Nitrogen Trioxy- fluoride NOaF --45.9 : 2.8 Reacts (4-0-4:1

Oxygen Difluoridc OF 2 -- 145 1.9 Slightly Soluble (4-0,0j

Perchloroyl Fluoride ClOsF --46.8 3.5 Very slow (3-0,0'.

Tetrafluorohydrazine NsF4 --73 3.6 Hydrolyzes (4-0~

*Hazard ratings in parentheses are temporary assignments.

40-1 ~ = .

REVISIONS TO NFPA NO. 4 0 475

Part VI

Reconfirmation of Standard for the Storage and Handling of

Cellulose Nitrate Motion Picture Film

NFPA No. 4 0 - - 1967

The Sectional Committee on Storage, Handling and Transpor- t ~ll0n of Hazardous Chemicals recommends that the 1967 edition r the Standard for the Storage and Handling of Cellulose Nitrate

~q0tion Picture Film, NFPA No. 40, be reconfirmed as suitable for , qTrent use. References will be updated in the reconfirmed edition.

476 PURGED ENCLOSURES - - GENERAL PROVISIONS 496-5

Part VII

Complete Revision of Standard for

Purged and Pressurized Enclosures for

Electrical Equipment in Hazardous Locations

NFPA No. 496~ 1972

PART A. PURGED ENCLOSURES FOR ELECTRICAL E Q U I P M E N T IN CLASS I H A Z A R D O U S LOCATIONS

Chapter 1 General Provisions

1-1 Object and Scope.

1-1.1" The object of Part A of this Standard is to provide inf0r. mation for the design of purged enclosures for the purpose of elimin. ating or reducing within the enclosure a Class I hazardous location classification, as defined in Article 500 of the National Electrical Code, N F P A No. 70--7977. By this means, equipment which is nr otherwise acceptable for hazardous locations may be utilized ir accordance with the National Electrical Code.

1-2 Equ ipment and Locations Covered.

1-2.1 Part A of this Standard applies to instruments, contrc rooms, motors, motor controllers, switchgear, and similar equil~ ment.

1-2.2 Part A of this Standard applies to locations where flail mable gases or vapors may be present ~in air in concentrations sull cient for the locations to be classified as hazardous.

*An asterisk beside a number indicates that Appendix A contains relat information.

Appendix A Appendix A is not a part of this Standard. It is included for information purposes o:

A1-1.1 Electrical equipment should be located in the area having as lov degree of hazard classification as practicable.

477 496- -0 PURGED AND PRESSURIZED ENCLOSURES

1-3 Degree of Hazard.

1-3.1 There are two degrees of hazard: 1, normally hazar- (00us (Division 1), and 2, hazardous only under abnormal conditions ~l)ivision 2).

I-3.2 The degree of hazard may be safely reduced (Division 0 to Division 2), or may be eliminated (Division 1 or Division 2 to ~0ahazardous) by purging, provided the installations are properly (~e~igned, installed, and maintained.

I-4 Definitions.

Division 1 Locations are those (1) in which hazardous concen- f~ations of flammable gases or vapors exist continuously, intermit- f~iltly, or periodically under normal operating conditions; (2) in vhlch hazardous concentrations of such gases or vapors may exist rTequently because of repair or maintenance operations or because ~ leakage; or (3) in which breakdown or faulty operation of equip-

, ~ent or processes which might release hazardous concentrations of ~t , lmable gases or vapors might also cause simultaneous failure of f~ctrical equipment.

Division 2 Locations are those (1) in which volatile flammable t ~uids or flammable gases are handled, processed or used, but in r the hazardous liquids, vapors or gases will normally be con- ~.r within closed containers or closed systems from which they I r escape only in case of accidental rupture or breakdown of such (~ta iners or systems, or in case of abnormal operation of equip-

"cot; (2) in which hazardous concentrations of gases or vapors are r|:~'~mally prevented by positive mechanical ventilation, but which tl ~ h t become hazardous through failure or abnormal operation of I '~ ventilating equipment; or (3) which are adjacent to Division 1 1! gotions, and to which hazardous concentrations of gases or vapors ~ ~ht occasionally be communicated unless such communication is i,,~;r by adequate positive-pressure ventilation from a source of . .;'an air, and effective safeguards against ventilation failure are pro- .' ~:~ed.

Purging is the process of supplying an enclosure with clean air or r 1 ~nert gas at sufficient flow and positive pressure to reduce to an

~:r safe level the concentration of any flammable gases or r initially present, and to mainta in this safe level by positive

,~.~'~ure with or without continuous flow.

478 P U R G E D E N C L O S U R E S - - G E N E R A L P R O V I S I O N S 4 ~ ,

T y p e X P u r g i n g reduces the classification within an enel0~ from Division 1 to nonhazardous.

T y p e Y P u r g i n g reduces the classification within an enclo~t~'~ from Division 1 to Division 2.

T y p e Z P u r g i n g reduces the classification within an enclosIc~# from Division 2 to nonhazardous.

P U R G E D A N D P R E S S U R I Z E D E N C L O S U R E S 479

* [)tpter 2 Purged Instrument and Other Small Enclosures

~bl S c o p e .

2-1.1 Chapter 2 applies to enclosures with a gross internal vol- : ~ not exceeding 10 cubic feet. For larger enclosures see Chapters

-~(I 4.

ll~ Gene ra l Requirements.

2-2.1 The enclosure shall be of such noncombustible material ,t "al construction that is not likely to be broken under conditions to r it is likely to be subjected.

2-2.2 Any window in a purged enclosure shall be tempered r at least ~ inch thick, shat terproof glass or other shat terproof

~terial.

2-2.3 I f hazardous vapors or gases have collected within the r162 either because the enclosure has been opened or the purge ~'21~ failed, then the enclosure shall be purged.

2-2.3.1 Once the enclosure has been purged of hazardous COncentrations, positive pressure shall be maintained within the fnclosure.

NOTE: It is not obligatory to maintain any given flow rate.

2-2.4* Compar tments within the main enclosure or adjacent enclosures connected to the main enclosure shall be considered ~eparately and protection shall be provided by one of the following Ihree methods:

Appendix A (Continued)

A2-2.4 In order for any internal or adjacent enclosure to be automatically purged as the main enclosure is purged, adequate vents must be provided to perm/t air circulation between it and the mafia enclosure. The area required to provide adequate venting will obviously depend upon the internal or adjacent enclosure. It is considered that meeung this requirement will prevent the formation of unpurged pockets of gas within the enclosure. It is not intended to imply that ihternal or adjacent enclosures not meeting these venting requi.rements ~ prohibited but that such enclosures must be provided with metr own purging gas connections.

480 PURGED~IALL ENCLOSURES 496-0

1. The compartment shall be vented to the main enclosu,~e b) nonrestricted top and bottom vents, common to the purged malr enclosure, having a minimum size for each vent of one square in(h per 400 cubic inches of the volume of the internal or adjaeelt! enclosure.

2. The compartment shall be separately purged, or 3. The equipment in the compartment shall be protected I)~

other approved means.

2-2.5 To exclude the entrance of flammable vapors or g a ~ in the event that the enclosure is opened or the purging system failh suitable devices such as indicators'or interlocks shall be provided.

2-2.6 The purging supply shall be essentially free of dust and liquids, which can plug small openings. I t shall contain no more than trace amounts of flammable vapors or gases.

2-2.6.1 Air of normal instrument quality shall be consid. ered acceptable as shall other suitable supplies such as inert gas.

NOTE: Ordinary plant compressed air is usually not suitable.

2-2.6.2 The compressor suction line shall be designed to pre. vent leaks which might permit hazardous vapors to be drawn into the compressor.

2-2.6.3 If air is used the compressor intake shall be located in a nonhazardous area.

2-2.6.4* If the compressor suction line passes through a hazardous area, it shall be constructed of noncombustible material! designed to prevent leaks of hazardous vapor into the system, and suitably protected against mechanical damage and corrosion.

2-2.7 When double purging is used, i.e., a room ventilated to make it Division 2 and containing a device with open contacts pro. tected by purging, the two sources of air shall be independent or automatic shutdown shall be provided.

2-3 Specific Requirements for T y p e Z Purg ing .

NOTE: Type Z purging reduces the classification within an enclosure from Division 2 to nonhazardous. A hazard is created under Type Z conditions only if the purge should fail at the same time the area which is nor* mally nonhazardous becomes hazardous. Because of this/it is not considered essential to remove power from the equipment upon failure of the purge

Appendix A (continued) A2-2.6.4 The compressor suction line should preferably not pass through

any area having hazardous atmospheres.

496-10 PURGED AND PRESSURIZED ENCLOSURES 481

but only that adequate warning must be provided to prevent continuing operation without purge protection.

2-3.1" Power shall not be turned on unti l at least four enclo- r volumes of purge gas have passed through the enclosure while !~,alntaining an internal enclosure pressure of at least 0.1 inch of ~atcr .

~ception: Power may be turned on immediately if a pressure of at least O. 1 ~th of water exists and if the atmosphere within the enclosure is known to be r

2-3.2* The enclosure shall be main ta ined under a positive pressure of not less than 0.1 inch of water when the power is on.

2-3.3* Unde r normal operat ion the external enclosure temperature or the tempera ture of the egress air shall not exceed 80 percent of the ignit ion temperature (~ of the vapor or gas involved ~ determined by Method of Test for Autogenous Ign i t ion T e m - ptratures of Pet ro leum Products, A S T M D2155--66. (See B? in ~ppendix B.)

~r162 Temperature limits of the gases or vapors involved may be ex- ~r iJ a qualified testing laboratory has determined that the excessively hot ~r will not ignite the specific gases or vapors involved.

2-3.4 A visual or audible a la rm to indicate purge system |allure shall be provided. Safety interlocks shall not be required.

2-3.4.1 The a larm shall be so located that it can be readily r or heard.


A2,-3.1 Any time the enclosure has been opened or the purging gas removed, q~re exists the possibility that explosive gases or vapors have accumulated r the enclosure. For enclosures effecuvely divided by internal parts into two or more separate spaces a greater purge volume may be advisable.

A2-3.2 The reason for requiring that a positive pressure be maintained is ~o prevent flammable vapors or gases from being forced into the enclosure by r air velocities.

A2-3.$ In the event that an external enclosure temperature in excess of the ~nhlon temperature of the gas or vapor involved existed, it is obvious the ~,rglng cannot prevent an explosion; therefore, it is essential that excessive t~,fface temperature be prevented, except when it has been specifically shown tO be safe by a qualified testing laboratory.

4 8 2 PURGED SMALL ENCLOSURES 496-11

2-3.4.2 It shall be acceptable for the visible or audil)lr alarm device to be mechanical, pneumatic, or electric.

2-3.4.3 If the alarm device is electrical it shall be suitable for use in the location in which it is installed.

2-3,4.4 If the alarm device is pneumatic any restrictio, between it and the enclosure shall have passages no smaller than the smallest passage before the pneumatic device in order to avoid plugging.

2-3.4.5 If a pneumatic indicator is used, no valve betwee, the device and the enclosure shall he permitted.

Nameplate Enclosure

R e s t r i c t i o n s may ol Ji may not be provided " ~ IL as des ired provided ( ~ basic requirements ~ J~ ~ Flow are met. / Indicator

Purging ~ Supply

Figure 2-3a

%Vurning Numcplale ~

.,a,o Indicator - ( ~

Purging Supply ----~ )

Figure 2-3b

t-- a,iure ~ ~ Plu~.v.ea _ .

P . . . . . . . G a ~ I[

Supply

P, ;irnim~ .~ ;imvphilt.

F~IU'III~Ii r t"

•.'S| firt Ittn |~ Possnges in "B" not smalleT than passages in "A"

. . . . . He~;t tictinn A

l Figure 2-3c

Acceptable installations for Types Y and Z purging

496-12 P U R G E D A N D P R E S S U R I Z E D E N C L O S U R E S 483

2-3.4.6 The pressure or flow device shall be capable of indicating (or actuating an alarm) when the purging pressure or flow is inadequate to maintain a static pressure within the enclosure of at least 0.1 inch of water.

2-3.5 A warning nameplate shall be mounted on the enclosure. The nameplate shall be mounted in a prominent location and be visible before the enclosure is opened. I t shall contain the following or equivalent statement:

Enclosures shall not be opened unless area is known to be nonhazardous or unless the power has been removed from all devices within the enclosure. Power shall not be restored after enclosure has been opened until enclosure has been purged for X minutes.

2-3.5.1 The manufacturer shall recommend purge condi tions and flow rate necessary to pass at least four enclosure volumes in the stated time X.

2-3.6 The maximum operating temperature of any internal nurface exposed to the atmosphere within the enclosure shall not exceed 80 percent of the ignition temperature (~ of the gases or vapors involved, as determined by ASTM D2155-66 (See BI in Ap- pendix B.) except that:

Exception: Temperature limits of the gases or vapors involved may be ex- teeded if a qualified testing laboratory has determined that the excessively hot tomponents will not ignite the specific gases or vapors involved.

2-3.6.1 If the device has not been tested by a qualified testing laboratory and any temperature exists over 80 percent of the ignition temperature of the gases or vapors involved, then

(a) The warning nameplate shall contain a statement that such conditions exist and that power shall be removed for X minutes (period to be determined and specified by the manufacturer to be nufficient to permit unit to cool to safe limit) before the door is opened unless the area is demonstrated to be nonhazardous at the time, or:

(b) The hot component shall be separately housed so that the surface temperature of its housing is below safe limits. This housing shall be purged or sealed and provided with a warning nameplate stating that its cover shall not be removed for X minutes (per- lad to be determined and specified by the manufacturer to be sufficient to permit unit to cool to safe limit) unless the area is demonstrated to be nonhazardous at the time.

2-4 Specific Requirements for Type Y Purging.

484 PURGED SMALL ENCLOSURES 496- I~

NOTE: Type Y purging reduces the classification within an enclosure from Division 1 to Division 2. The equipment that can be included within the enclosure under Type Y conditions must be suitable for Division 2. This requires that it d ~ not normally contain a source of ignition. Thus, a hazard is created within the enclosure only upon failure of the purging system simultaneously with a failure of the internal equipment causing it to produce a source of ignition. Therefore, it is not considered essential that on failure of the purging system the power be automatically removed from the equipment but that a warning be provided to prevent continuing operation without purge protection.

2 -4 .1 All r e q u i r e m e n t s in 2-3.1 to a n d i n c l u d i n g 2 -3 .5 shall be met .

2 - 4 . 2 E q u i p m e n t shall c o n f o r m to the r e q u i r e m e n t s for Divi- sion 2 loca t ions as fol lows:

2--4.2.1" M a k e - a n d - b r e a k or s l id ing con tac t s shal l be e i ther i m m e r s e d in oil, o r enc losed w i th in a c h a m b e r h e r m e t i c a l l y sealed aga ins t the e n t r a n c e of gases o r vapors , o r in c i rcu i t s w h i c h unde r n o r m a l cond i t ions do no t release suff ic ient e n e r g y to igni te a specific h a z a r d o u s a t m o s p h e r e mix tu re .

2 - 4 . 2 . 2 " T h e m a x i m u m o p e r a t i n g t e m p e r a t u r e of any surface exposed to the a t m o s p h e r e w i t h i n the enc losu re shall n o t exceed 80 p e r c e n t of the ign i t ion t e m p e r a t u r e (~ of the gases or vapo r s invo lved , as d e t e r m i n e d by A S T M D 2 1 5 5 - 6 6 . (See BI in Appendix B.)

Exception No. 1: Temperature limits of the gases or vapors involved may be exceeded if a qualified testing laboratory has determined that the excessively hot components will not ignite the specific gases or vapors involved.

Exception No. 2: Temperature limits of the gases or vapors involved may be exceeded if the surface having this temperature is enclosed within a chamber hermetically sealed against the entrance of gases or vapors.


A2-4.2.1 Examples of contacts normally operating at energy levels that would not cause ignition are: slide-wire and switching contacts in thermocouple circuits, reststance thermometer, strain gauge and pH electrode.

A2-4.2. o Internal temperatures above the ignition temperature of the gas or vapor involved, such as vacuum tube filaments, are hermetically sealed to ~r them from normally coming in contact with the atmosphere that may

ome hazardous. It is essential that in such enclosures the surface of the glass envelope that does come in contact with the atmosphere not have a tem- iPenvrature in excess of 80 percent of the ignition temperature of the gas or vapor

olved, unless specifically shown to be safe by a qualified testing laboratory.


2-4.3 If the conditions specified under 2-4.2 are met, it shall be acceptable to locate the equipment in a general purpose enclosure without purging.

2-5 S p e c i f i c R e q u i r e m e n t s for T y p e X P u r g i n g .

NOTE: Type X purging reduces the classification within an enclosure from Division 1 to nonhazardous. Because the probability of a hazardous concentration of gas or vapor external to the enclosure is high and the enclosure normally contains a source of ignition, it is essential that any disruption of the purging will result in the removal of power from the equipment. Also, it is essential that the enclosure be tight enough to prevent escape of molten metal particles or sparks.

2-5.1 A t iming device shall be incorpora ted to prevent power from being app l i ed unt i l af ter the elapse of a t ime sufficient to pe rmi t at least four enclosure volumes of purge gas (ten for motors) to have passed th rough the enclosure while ma in t a in ing an in ternal pressure of at least 0.1 inch of water .

2-5.1.1 T h e t iming device shall be sui table for use in the location in which it is installed.

2-5 .1 .2 T h e manufac tu re r shall r e commend purge condi - tions and flow rate necessary to pass four enclosure volumes in a stated t ime.

2 -5 .2 T h e enclosure shall be ma in ta ined unde r a positive pressure of not less than 0.1 inch of wa te r when the power is on.

2-5 .3 A device shall be incorpora ted to remove poten t ia l au tomat ica l ly from all circuits wi th in the enclosure not sui table for Division 1 upon fai lure of the purg ing supply.

NOTE: See Section 2-5.6 for requirements for cutoff switches.

2-5.4* A doo r switch shall be provided to remove potent ia l au tomat ica l ly from all circuits wi th in the enclosure not sui table for Division 1 if the enclosure can be readi ly opened wi thout the use of a key or tools.


A2-5.4 It is considered essential that any door or other opening which can be opened by untrained people without tools be protected w~th door interlock switches. Consistent with the practice which has been established with e x -

plosionproof enclosures, it is considered that the commonly displayed warning nameplate is adequate protection for the enclosure that can only be opened by the use of suitable tools.

486 PURGED SMALL ENCLOSURES 496-15

2-5.4.1 The door switch, even though located within the enclosure, shall be suitable for Division 1 locations.

2-5.5* The maximum operating temperature of any surface exposed to the atmosphere within the enclosure shall not exceed 80 percent of the ignition temperature (~ of the gases or vapors involved, as determined by ASTM D2155-66. (See BI in Appendix B.)

Exception No. 7: Temperature limits of gases or vapors involved may be exceeded if a qualified testing laboratory has determined that the excessively hot components ~'l l not ignite the specific gases or vapors involved.

Exception No. 2: Temperature limits oJ gases or vapors involved may be exceeded if the surface having this temperature is enclosed within a chamber hermetically sealed against the entrance of gases or vapors.

2-5.5.1 Equipment such as motors, transformers and other equipment which may .be overloaded shall be provided with appropriate devices to detect any increase in temperature of the equipment beyond design limits and to de-energize the equipment automatically.

2-5.6 The power cutoff switch provided to remove power upon failure of the purging system shall be either flow or pressure actuated.

2-5.6.1 It shall be suitable for use in the location in which it is installed.

2-5.6.2 To avoid plugging when a pneumatic device is used, any restrictions between the device and thc enclosure shall have passages no smaller than the smallest passage before the device.

2-5.6.3 If a pneumatic device is used, no valve between the device and the enclosure shall be permitted.

2-5.6.4 The pressure or flow device of Figure 2-5a and Figure 2-5b shall be capable of cutting off power when the purging pressure or flow is inadequate to maintain a static pressure within the enclosure of at least 0.1 inch of water.


A2-5.5 Because the source of ignition caused by high temperature is not immediately removed by cutting off power to the equipment, it is considered essential that no surface temperature approaching the ignition temperature of the gas or vapor involved should be permitted to come in contact with the internal enclosure atmosphere, unless specifically shown to be safe by a qualified testing laboratory.

Warning .Nameplate

Pt.essure Actuated Cut-off Switch

Purging Supply

.3ndmm~

Figure 2-5a

Endmane

Warning Nameplate-- ~ _ ~

Restriction / Optional

Restrictions may; or may not be provided as desired provided basic requirements are met

Enttosure

Restriction B --

~ " Flow "~ Actuated J Cut-off

Switch

Purging %._ Supply ~

Figure 2-5b

Passages in " B " not smaller than pss. in " A "

Restriction A

P u q ~ i n g ~ Supply

Figure 2-5c

Acceptable installatlons, for Type X purging

Air Pressure Failure

Safe

l Pressure Actuated Cut-off Switch Cutting Off on Low or High Conditions.

Plugged

-.4

488 PURGED SMALL ENCLOSURES 496-17

2-5.6.5 The pressure device of Figure 2-5c shall be capable of cutting off power if pressure exceeds or falls below a prede. termined safe range.

2-5.7 A warning nameplate shall be mounted on the instru. merit in a prominent location and be visible before the enclosure is opened. It shall contain the following or an equivalent statement: Enclosure shall not be opened or any cover removed unless area ia known to be nonhazardous or unless the power has been removed from all devices within the enclosure. Power shall not be restored after enclosure has been opened until enclosure has been purged for X minutes.

2-5.7.1 The manufacturer shall recommend purge conditions and flow rate necessary to pas~ at least four enclosure volumes in the stated time X.

496-18 PURGED AND PRESSURIZED ENCLOSURES 4t;9

Chapter 3 Purged Control Rooms

3-1 General.

3-1.1" These requirements apply to bui ld ings .or portions of buildings, commonly referred to as control rooms, when located close to areas which may conta in f lammable atmospheres.

3-1.2" If the control room is located in a hazardous area, it shall be designed to prevent the entry of f lammable liquids and f lammable atmospheres.

3-2 Cons ide ra t i ons R e l a t i n g to Pos i t ive P ressure V e n t i l a - t ion.

3-2.1 The following factors shall be considered in designing a control room suitable for safe operat ion in hazardous atmospheres.

The n u m b e r of people to be housed.

T h e type of equ ipmen t to be housed.

The location of the control room in relation to the process units, including the location of relief valves and vent stacks, and the direction of the prevail ing wind.

Appendix A (Continued) A3-1.1 Control rooms commonly house one or more of the following facilities:

Process control instruments and panels. Data processing equipment. Communications equipment. Electrical lighting and electrical power equipment and controls. Emergency power-producing equipment to serve lighting and control de-

vices. Lunch, restroom and locker facilities for operating personnel. Offices for process supervisors and technical personnel. Maintenance facilities for calibration and repair of process instruments and

control devices. Heating and ventilating equipment.

In the process which can create hazardous atmospheres, the control room may serve as a separated location for devices capable of releasing sufficient electrical or thermal energy to cause ignition.

A3-L2 To prevent the entrance of flammable liquids may require differences in elevation and-or the use of dikes, etc. To prevent the entry of flammable atmospheres positive pressure ventilation from a source of clean air may be used and the equipment in the building need not be housed in special enclosures for safe operation.

490 PURGED CONTROL ROOMS 496-19

3-2.2* The source of air for purging control rooms shall be free of hazardous concentrations of flammable vapors and gases, contaminants and any other foreign matter.

3-2.2.1" The source of air shall be determined from the nature of the process and the physical layout.

3-2.2.2 Ducting shall bc constructed of noncombustible material. The fan suction line shall be free of Icaks and given suitablc protection from mechanical damage and corrosion to prevent hazardous concentrations of flammables from being admitted to the control room.

3--2.3.3* The air system shall bc designed to provide positive-pressure ventilation for all areas of the room.

3-3 Requirements for Positive Pressure Air Systems.

3-3.1" The positive pressure air system shall:

(a) be capable of main ta in ing a pressure of at least 0.1 inch of wa te r in the control room with all openings closed, and

(b) be capable of providing a m i n i m u m outward velocity of 60 feet per minute th rough all openings. All doors and windows capable of being opened shall be considered as open, and an allow- ance for o ther openings shall be included.

3-3.1.1 I t shall be acceptable for the positive pressure air system to include heating, vent i la t ing and air condi t ioning equipment plus any auxil iary e q u i p m e n t found necessary to comply with the above.

Appendix A (Continued) A3-2.2 Air filtering may be desirable.

A3-2.2.1 Ordinarily air can be taken from an area to one side of a process area where there is a minimum chance of flammable vapors being found. The elevation of the fan suction depends on the density of the flammable gases or vapors under handling temperatures and adverse atmospheric conditions. For a control room in the center of a process, ducting may be necessary.

A3-2.2.3 Monitoring devices such as gas analyzers or similar devices may be needed to detect flammable vapors and gases and give suitable warning.

A3.-3.1 A minimum number of doors should be provided so that positive pressures can be maintained, while at the same time the number of doors should be adequate for safe exit.


3-3.2 If there is an a i r -consuming device in the control room, sufficient air shall be supplied to handle its needs plus the needs of the positive pressure air system requirements or the air shall be taken from a separate source.

3-3.~3 If Type X purg ing is required, all power to the control room shall be automat ical ly shut down upon air system failure.

NOTE: Cutting off power to the control room may shut down the process, and this fact shall be considered.

3-3.4 For Types Y and Z purging, shutdown of power to the control room shall not be required.

3-3.5* The positive pressure air system failure shall be sensed by the discharge pressure of air from the fan and be signaled by a visible or audible alarm.

3-3.5.1 The visual or audible a larm shall be so located that it can be readily noticed and action can be taken.

3-3.6 Provisions shall be made to energize the control room safely after an air system interrupt ion. Such provisions are:

3-3.6.1 Check with a f lammable vapor indicator to determine when it is safe to energize the control room.

3-3.6,2* Provide a switch, motor and disconnect for the fan suitable for the area as it would be classified in the absence of positive pressure ventilation.

3-3.6 .3 The electrical power for the air system fan shall be taken off the power line ahead of any disconnects that must be energized to re turn power to the control room.


A3-3.5 Velocity pressure switches, static pressure sensing devices and plenum chambers with orifices to provide sufficient pressure to be sensed have been used. Electrical interlocks on the fan motors are not adequate in the event the fan belt slips, the fan impeller becomes hMlse nn the shaft or if the fan rotation is backwards.

A3-3.6.2 An enforced purge wherein an interlock system requires proof of purging for a set period of tilne prior to energization should be considered if warranted by the conditions.

492 PURGED POWER EQUIPMENT ENCLOSURES 496-21

Chapter 4. Purged Power Equipment Enclosures

4-1 Scope. 4-1.1 Chapter 4 applies to equipment enclosures exceeding 10

cubic feet in volume but not control rooms. For enclosures with a volume of 10 cubic feet or less see Chapter 2; for control rooms see Chapter 3.

4-1.2 For purposes of purging, electrical power equipment can be divided into two groups:

4-1.2.1 P u r g e d Equ ipment . Equipment, such as switchgear and motor controllers, which does not require air flow for heat dissipation, but which requires pressurization to prevent entrance of flammable gases or vapors.

4-1.2.2 Vent i la ted Equ ipment . Equipment, such as motors, which requires air flow for heat dissipation.-

4-2 Requirements for Purged Equipment. 4-2.1 The enclosure shall be of substantial noncombustible

construction and reasonably tight. Gaskets shall be permissible.

4-2.2 The source of air shall be free of hazardous concentrations of flammable vapors and gases, contaminants and any other foreign matter.

4-2.3 Piping for air or inert gas supply (if used) shall be protected against mechanical damage.

4-2.4 Whether the type of purging is X, Y or Z, before power is turned on at least ten enclosure volumes of purge gas shall have passed through the enclosure while internal enclosu.re pressure of 0.1 inch of water or more is maintained. This pressure shall be maintained continuously.

Exception: In the cases of Y and ~ purging, power may be turned on immediately if a pressure of at least O. 1 inch of water exists and if the atmosphere within the enclosure is known to be nonhazardous.

4-2.5 Under normal operating conditions the external enclosure temperature or the temperature of the egress air shall not exceed 80 percent of the ignition temperature (~ of the vapor or gas involved.as determined by ASTM D2155-66. (See B1 in Appendix B.)

496-22 PURGED AND PRESSURIZED EN CLO SU RES 493

b~xeeption: Temperature limits of the gases or vapors involved may be exceeded if a quali~ed.testing laboratory has determined that the excessively hot r will noi ignite the specific gases or vapors involved.

4-2.6 In the case of loss of pressurization, power to the equipment shall be removed immediately in the case of X purging, unless hnmediate interruptation of power would result in a condition more hazardous than that created by failure to remove the power immediately. In this case an audible as well as visual alarm suitable for the area shall be energized. In the cases of Y and Z purging, loss of pressurization shall energize an audible as well as a visual alarm. Removal of power shall not be required in the cases of Y and Z purging failures.

4-2.6.1 The visual or audible alarm shall be so located that it can be readily noticed and action can be taken.

4-2.7 A warning nameplate shall be mounted on the enclosure in a prominent location and be visible before the enclosure is opened. It shall contain the following or an equivalent statement:

Enclosure shall not be opened unless area is known to be nonhazardous or unless the power has been removed from all devices within the enclosure. Power shall not be retored after enclosure has been opened until enclosure has been purged for X minutes. NOTE: There should be a flow rate to pass at least ten enclosure volumes

in the stated time X.

4-2.8 The maximum operating temperature of any internal surface exposed to the atmosphere within the enclosure shall not exceed 80 percent of the ignition temperature (~ of the gases or vapors involved, as determined by ASTM D2155-66. (See BI in Ap- pendix B.)

Exception No. 1: Temperature limits of the gases or vapors involved may be exceeded if a qualified testing laboratory has determined that the excessively hot components will not ignite the specific gases or vapors involved.

Exception No. 2. Temperature limits of the gases or vapors involved may be exceeded if the warning nameplate contains a statement that such conditions exist and that power shall be removed for X minutes (period to be determined and specified by the manufacturer to be su~cient to permit unit to cool to safe limit) before the door is opened unless the area is demonstrated to be nonhazardous at the time.

Exception No. 3. Temperature limits o/the gases or vapors involved may be exceeded if the hot component is separately housed so that the surface temperature of its housing is below safe limits. This housing shall be purged or

494 PURGED POWER EQUIPMENT ENCLOSURES 496-23

sealed and provided with a warning nameplate stating that its cover shall not be removed for X minutes (period to be determined and specified by the manu. facturer to be sufficient to permit unit to cool to safe limit) unless the area is demonstrated to be nonhazardous at the time.

4-2.8.1 For Type X purging, equipment such as motors, transformers and other equipment which may be overloaded shall be provided with appropriate devices to detect any increase in temperature of the equipment beyond design limits and to de-energize the equipment automatically.

4-3 Requirements for Ventilated Equipment.

4-3.1 The enclosure shall be noncombustible construction with necessary openings limited to minimum practical fize and kept as airtight as possible.

4-3.2 The enclosure shall be purged by at least ten (10) air changes before the electrical equipment is energized. The auxiliary air equipment shall be suitable for the location.

4-3.3 The enclosure shall be constantly maintained at a pressure of at least 0.1 inch of water above the surrounding atmosphere during operation of the equipment.

4-3.4 The source of air for ventilation shall be free of hazardous concentrations of flammable vapors and gases, contaminants and any other foreign matter.

NOTE: Air filtering may be desirable.

4-3.5 Air discharge from the enclosure shall be to an area classified nonhazardous or Division 2.

4-3.6 The flow of air shall be as uniform as possible within the enclosure so as to avoid, or at least minimize, air pockets.

4-3.7 The flow of air shall be adequate to keep the equipment adequately cooled depending on the operating design requirements.

NOTE: The air required for cooling will be more than that required for purging.

4-3.8 The maximum operating temperature of any surface exposed to the atmosphere shall not exceed 80 percent of the ignition temperature (~ of the gases or vapors involved, as determined by ASTM D2155--66. (See B I in Appendix B.)


~r Temperature limits of the gases or vapors involved may be ex- ~r if a qualified testing laboratory has determined that the excessively ~ l components will not ignite the specific gases or vapors involved.

4-3.9 The electrical circuits of the equipment within the fnclosure shall be interlocked with the ventialting equipment so thnt:

(a) The equipment cannot be energized until the purging cycle |ells been completed.

(b) The equipment will automatically shut down when the ventilating equipment stops.

l~rception: I f shutting down the equipment can produce unsafe conditions, on audible as well as visible signal shall be energized so that corrective steps can be taken.

496 P U R G E D E N C L O S U R E S ~ G E N E R A L P R O V I S I O N S 596-2/;

PART B. PRESSURIZED ENCLOSURES FOR ELECTRICAL E Q U I P M E N T IN CLASS II H A Z A R D O U S LOCATIONS

Chapter 5 General Provisions

5-1 Object and Scope.

5-1.1 The object of Part B of this Standard is to provide information for the design of pressurized enclosures for the purpose of eliminating within the enclosure a Class l I hazardous location classification, as defined in Article 500 of the National Electrical Code, NFPA No. 7 0 - - 1971. By this means, equipment which is not otherwise acceptable for hazardous locations may be utilized in accordance with the National Electrical Code.

5-2 Equipment and Locations Covered.

5-2.1 Part B of this Standard applies to control rooms and enclosures for instruments, motors, motor controllers, switchgear, and similar equipment.

5-2.2 Part B of this Standard applies to locations which are hazardous because of the presence of combustible dust.

5-3 Definitions.

Class II, Division 1. Locations (1) in which combustible dust is or may be in suspension in the air continuously, intermittently, or periodically under normal operating conditions, in quantities sufficient to produce explosive or ignitible mixtures, (2) where mechanical failure or abnormal operation of machinery or equipment might cause such mixtures to be produced, and zRight also provide a source of ignition through simultaneous failure of electrical e~luipment, operation of protective devices, or from other causes, or (5) in which dusts of an electrically conducting nature may be present.

NOTE: Combustible dusts which are electrically nonconducting include dusts produced in the handling and processing of grain and grain products, pulverized sugar and cocoa, dried egg and milk powders, pulverized spices, starch and pastes, potato and wood flour, oil meal from beam and seed, dried hay, and other organic materials which may produce combustible dusts when processed or handled. Electrically conducting nonmetallic dusts include dusts from pulverized coal, coke and charcoal. Dusts containing magnesium or aluminum are particularly hazardous and every pre- caution must be taken to avoid ignition and explosion.


Class I I , D i v i s i o n 2. Locat ions in which combus t ib le dust will IIot no rma l ly be in suspension in the air, o r will not be l ikely to be Ihrown into suspension by the normal opera t ion of e q u i p m e n t or ap.paratus, in quant i t ies sufficient to p roduce explosive or igni t ible mtxtures, but (1) where deposi ts or accumula t ions of such dust may be sufficient to interfere with the safe dissipat ion of hea t from electr i- cal equ ipmen t or appara tus , or (2) where such deposi ts or accumulations of dus t on, in, or in the vicini ty of electr ical e q u i p m e n t might he ignited by arcs, sparks or burn ing ina ter ia l f rom such equ ipmen t .

P r e s s u r i z a t i o n for the purposes of this S t a n d a r d is the process of supplying an enclosure wi th clean a i r or an iner t gas wi th or wi thout cont inuous flow at st, fficient pressure to prevent the en t rance of hazardous dusts.

NOTE : An atmosphere made hazardous by dust inside an enclosure cannot be reduced to a safe level by supplying a flow of clean air in the same manner as gases or vapors. The enclosure must be opened and the dust removed. Visual inspection can be used to determine if the dust has been removed. Positive pressure will prevent entrance of a dust into a clean enclosure.

5-4 Degree of Hazard.

5-4 .1" In both Division 1 and Division 2 locations, the haza rd can be e l imina ted by pressur izat ion to p reven t the en t rance of combustible dusts, p rov ided the instal lat ions are p roper ly designed, installed and main ta ined .


A5-4.1 Electrical equipment should be located in the area having as low a degree of hazard classification as practicable.

498 PRESSURIZED SMALL ENCLOSURES 496-27

Chapter 6. Pressurized Instrument and Other Small Enclosures

6-1 Scope.

6-1.1 Chapter 6 applies to enclosures with a gross internal volume not exceeding 10 cubic feet. For larger enclosures see Chapters 7 and 8.

6-2 General Requirements.

�9 6-2.1 The enclosure shall be reasonably tight and of such noncombustible material and construction that is not likely to be broken under conditions to which it is likely to be subjected.

6-2.1.1 Precautions shall be taken to protect the enclosure from excessive pressure of the pressurizing supply.

6-2.1.2 Excess pressure relieving devices, when required to protect in case of control failure, shall be designed to prevent escape of sparks or burning material to a hazardous area when they relieve.

6-2.2 Any window in a pressurized enclosure shall be tempered glass at least l/~-inch thick, shatterproof glass or other shatterproof material.

6-2.3 I f combustible dusts have collected within the'enclosure, the enclosure shall be opened and the dust removed; then the enclosure shall be pressurized.

6-2.4 Subdivisions within the main enclosure or" adjacent enclosures connected to the main enclosure may be collectively pressurized to prevent the entrance of dust if there is adequate communication to maintain the specified pressure at all points.

6-2.5 Suitable precautions such as indicators, pressure switches, and interlocks shall be provided to safeguard the installation if the enclosure is opened or if the pressurizing system fails.

6-2.6 The pressurizing supply shall be essentially free of dust and liquids which can plug small openings. I t shall contain no more than trace amounts of flammable gases or vapors.

6-2.6.1 Air of normal instrument quality shall be acceptable as shall other suitable supplies such as inert gas.

N O T E : Ord inary plant compressed air is usually not suitable due to con- tamlnanta which m a y cause equ ipment to malfunction.


6-2.6.2 The compressor intake shall be located in a non- h,l~.a rdous area.

6-2.6.3* If the compressor suction line passes through a hazardous area, it shall be of noncombustible material suitably pro- leered against mechanical damage and corrosion.

6-2.6.4 The compressor suction line shall be designed to prevent leaks which might permit hazardous vapors or dusts to be drawn into the compressor.

6-3 Specific Requirements for Pressurizing.

NOTE: A hazard is created within an enclosure only after the pressure has failed and enough dust to be explosive penetrates into the enclosure. This takes an appreciable time with any normally tight enclosure. Because of this, it is not always considered essential to remove the power from the equipment automatically upon failure of the pressurization. It is necessary only to provide an adequate warning so that operations will not continue indefi- nitely without pressure protection. It is essential that the enclosure be tight enough to prevent escape of sparks or burning material.

6 -3 .1 Before the p o w e r is t u r n e d on, the in t e r io r o f the enc lo- ture shall be free o f dust .

6 -3 .1 .1 I f c o m b u s t i b l e dusts h a v e co l l ec ted w i t h i n t he en - closure, it shal l be o p e n e d a n d the dus t r e m o v e d before pressur iz ing .

6 3 . 2 * T h e enc losure shall be m a i n t a i n e d u n d e r a pos i t ive pressure d e p e n d e n t on the specif ic pa r t i c l e dens i ty o f the dus t in a c c o r d a n c e w i t h the fo l lowing table , w h e n the p o w e r is on :

ific Particle Density nds per Cubic Foot)

130 or less

Greater than 130

Pressure (inches of Water)

Not Less than 0.1

Not Less than 0.5

A p p e n d i x A (Continued)

A6-2.6.3 The compressor suction line should preferably not pass through any nrea having hazardous atmospheres.

A6-3.2 The density of 130 pounds per cubic foot is slighdy greater than that of sulfur dust, which was one of the dusts used in performing the tests on which Ihe values in the table are based. The pressures in the table are based on the assumption that the maximum crack width exposed to falling dust is 1/64 inch wide. The ability of a dust to enter an opening due to the force of gravity against an outward velocity of gas is directly dependent on its specific particle density.

500 PRESSURIZED SMALL ENCLOSURES 496=~J

6-3.3" In Division I locations, a door switch shall be proyidr to remove power automatically from all circuits within the enclosuIr not suitable for Division I if the enclosure can be readily openr without the use of a key or tools. In Division 2 locations, no do01 switch is required as it is not necessary to remove the power to I|I~ enclosure automatically if the door is opened.

6-3.4 A warning nameplate shall be mounted on the encl0, sure. The nameplate shall be mounted in a prominent locati01~ and be visible before the enclosure is opened. I t shall state:

Enclosure shall not be opened unless the area is known to be nonhazardous or unless the power has been removed from all devices within the enclosure. Power shall not be restored after the enclosure has been opened until combustible dusts have been removed and the enclosure repressurized.

Exception: If there is not space on the enclosure to print this statement in type large enough to be legible, equivalent wording, such as the following ma$ be used:

De-energize before opening unless area is known to be nonhazardous. Re. move dust and repressurize before restoring power.

6-3.5 Under normal operation, the external enclosure temperature or the temperature of the egress air shall not exceed 80 percent of, and in all cases shall be at least 50 ~ C below, the ignition temperature (~ of the dust when in the form of a layer. The ignition temperature of the dust layer is determined by the procedure described in the U. S. Bureau of Mines Report of,Investigation 5624. (See B2 in Appendix B.) Equipment installed in Class I I locations shall be able to function at full rating without developing surface temperatures high enough to cause excessive dehydration or gradual carbonization of any organic dust deposits that may occur.

In general, maximum surface temperatures under actual operating conditions shall not exceed 165~ (329~ for equipment which is not subject to overloading, and 120~ (248~ for equipment such as motors, power transformers, etc., which may be overloaded.

NOTE: Dust which is carbonized or is excessively dry is highly susceptible to spontaneous ignition.

Appendix A (Continued) A6-3.3 Consistent with the practice which has been established with explosion-

proof enclosures, it is considered that the commonly displayed warning nameplate is adequate protection for the enclosure that requires the use of a tool to be opened.

496-30 PURGED AND PRESSURIZED E N C L O S U R E S

6-3.6* Any internal component having a surface temperature approaching the ignition temperature of the combustible dust involved shall be protected in accordance .with 6--3.6.1.

6-3.6.1 I f any internal component has a maximum surface temperature greater than that indicated ill 6--3.5, the surface having this temperature shall be enclosed within a chamber hermetically sealed or suitably gasketed against the entrance of combustible dusts, and of a size which will limit its exterior surface temperature to those specified in 6-3.5.

Exception .No. l: I f the chamber containing the component is not sealed or Racketed a warning nameplate shall be mounted on the outside of the enclosure and it shall contain a statement that such conditions exist and that ~ower shall be removed for minutes (period to be determined and specified Oy the manufacturer to be sufficient to permit unit to cool to safe limit) before the door is opened unless the area is known to be nonhazardous at the time or:

Exception No. 2: I f the chamber containing the component is not sealed or gacketed the hot component shall be separately housed so that the surface temperature of its housing is below safe limits. This housing shall be ~i essurized or sealed and provided with a warning anameplate stating that

cover shall not be removed for - - minutes (period to be determined and specified by the manufacturer to be sufficient to permit unit to cool to safe limit) unless the area is known to be nonhazardous at the time.

6-3.6.2 Equipment such as motors and transformers that may be overloaded and that is exposed directly to the dusty atmosphere shall be provided with appropriate devices to detect any increase in temperature of the equipment beyond design limits and to de-energize the equipment automatically.

Exception: I f immediate interruption of power would result in a condition more hazardous than that created by failure to remove the power, audible as well as visible alarms suitable for the area shall be energized.

6-3.7 An alarm or indication of pressurized system failure shall be provided. I t shall be acceptable for the device to be mechanical, pneumatic or electric, and the signal may be audible or visual.

6-3.7.1 I f electrical, the alarm device shall be suitable for use in the location in which it is installed.


A6-3.6 Because source of ignition caused by high temperature is not ira- mediately removed by cutting power to the equipment, additional precautions are necessary for hot components.

502 496-~J PRESSURIZED SMALL ENCLOSURES

6-3.7.2 To avoid plugging when a pneumatiC device is used, any restrictions between the pneumatic device and the enclosure shall have passages no smaller than the smallest passage before the pneumatic device.

6-3.7.3 If a pneumatic indicator is used, rio valve between the device and the enclosure shall be permitted.

�9 6-3.7.4 The pressure or flow device shall, be capabie of indicating (or actuating an alarm) when the purging pressure or flow is inadequate to maintain a static pressure within the enclosure as specified in 6-3.2. The device of Figure 6-3c shall also be capable of indicating (or actuating an alarm) if pressttre exceeds a predetermined safe range (indicates plugging of restriction B).

Restrtcttons my o r - - ~ - - may not: be provided | as desired provtdod I I .baste requtreaeato J ~ alto laet. ~. r ~ FLov

I?R.SSS'JRIZTJtG Supply

Watntn& _ _ ~ . . J J Ne~aeplate ~loouro

PI[GGBU~6 �9 Alar~:L and lt~dt�9

F igure 6-5a

PRSSSURZZIHO Supply

FigUre 6 - 3 b

o I = l a t tm tugs*d

alem end ~ I- tadtcSt~' - - '~ [ I

- - ] ~ . . . ~ t a t a 8 N~14r

J Knelg~mgo

J .J~ itutctr S |J IPmumgee tn up "l not emt|er item J[ ~ ~ ~ Ji~lJ

- - ~ - - ~ ,U ' ''�9176 &

n.F~SUP.| ZI~G Supply

Figure 6-3c

Acceptab le Instal lations for PressuTi~iag

496-32 ~ U 3 PURGED AND PRESSURIZED ENCLOSURES

Chapter 7 Pressurized Control Rooms

7-1 General.

7-1.1" These requi rements app ly to bui ldings or port ions of bui ldings c o m m o n l y referred to as control rooms when located close to areas which m a y conta in combust ib le dusts.

7-1.2 I f the control room is located in an area made hazar - dous by combust ib le dusts, it shall be designed to prevent the en t ry of combust ib le dusts. T o prevent the en t ry of combust ib le dusts it shall be accep tab le to use positive pressure vent i la t ion f rom a source of c lean a i r and the equ ipment in the bui ld ing need not be housed in special enclosures for safe opera t ion .

7-2 C o n s i d e r a t i o n s Relating to Positive Pressure Ventilation.

7-2.1 Factors to be considered in designing a control room suitable for safe opera t ion in hazardous a tmospheres are :

The n u m b e r of people to be housed (air condi t ion ing load) . T h e type of e q u i p m e n t to be housed. T h e locat ion of the control room in relat ion to the process units and potent ia l sources of dust , such as e levator legs, belt conveyers, and vent stacks.

7-2 .2 T h e source of a i r for pressurizing control rooms shall be free of hazardous concentra t ions of f lammable gases, vapors or combustible dusts, con taminan t s and any o ther foreign mat te r .

NOTE: Air filtering may be necessary.


AT-I.I Control rooms commonly house one or more of the following facilities:

Process control instruments and panels. Data processing equipment. Communications equipment. Electrical lighting andelectrical vower equipment and controls. Emergency power-producing equipment to serve lighting and control devices. Lunch, restroom and locker facilities for operating personnel. Offices for process supervisors and technical personnel. Maintenance facilities for calibration and repair of process instruments

and control devices. Heating and ventilating equipment. In processes which can create hazardous atmospheres, the control rooms

may serve as a separated location for devices capable of releasing sufficient electrical or thermal energy to cause ignition.

504 PRESSURIZED CONTROL ROOMS 496-33

7-2.2 .1 T h e source of a i r shall be de t e rmined from the na tu re of the process and the physical layout .

NOTE: Ordinarily air can be taken from an area to one side of a process area where there is a minimum chance of flammable gases, vapors, or com- bnstible dusts being found. The elevation of the fan suction depends on the density of the flammable gases or vapors or combustible dusts under handling temperatures and adverse atmospheric conditions. For a control room in the center of a process, ducting may be necessary.

7 -2 .2 .2 Duc t ing shall be const ructed of noncombust ib le materials .

7-2 .2 .3 T h e fan suction line shall be free of leaks and given sui table pro tec t ion from mechanica l d a m a g e and corrosion to prevent hazardous concent ra t ions from being a d m i t t e d to the control room.

7-2 .3 T h e a i r system shall be designed to provide positive- pressure vent i la t ion for all areas of the room.

7-3 R e q u i r e m e n t s for Positive Pressure Air Systems.

7-3.1" T h e positive pressure a i r system shal l : (a) be capab le of ma in t a in ing a pressure of a t least 0.1 inch of

wa te r in the control room wi th all openings closed, and (b) be capab le of p rov id ing a m i n i m u m o u t w a r d veloci ty of

60 feet pe r minu te th rough all openings. All doors and windows capab le of be ing opened shall be considered as open, and an al low- ance for o ther openings shall be included.

7-3.1.1 I t shall be accep tab le for posit ive pressure a i r system to include heat ing, vent i la t ing and a i r condi t ion ing equ ipmen t plus any aux i l i a ry e q u i p m e n t found necessary to comply wi th the above.

7 -3 .2 If there is an a i r -consuming device in the control room, sumcien t a i r shall be suppl ied to hand le its needs plus the needs of the positive pressure a i r system requ i rements or the a i r shall be taken from a separa te source.

7-3 .3 Positive pressure a i r system fai lure shall be sensed by the discharge pressure of a i r f rom the fan and be s ignaled by a visible or aud ib le a la rm. P r o m p t measures shall be taken to restore pressurizat ion.

Appendix A (Continued) A7-3.1 A minimum number of doors should be provided so that positive

pressure can be maintained, while at the same time the number of doors should be adequate for safe exit.

496-34 PURGED AND PRESSURIZED EN CLO SU RE S 505

7 - 3 . 3 . 1 T h e v i sua l o r a u d i b l e a l a r m sha l l be so l oca t ed IJltlt it c a n b e r e a d i l y n o t i c e d a n d a c t i o n c a n be t a k e n .

NOTE: Velocity pressure switches, static pressure sensing devices and plenum chambers with orifices to provide sufficient pres.qure to be sensed have been used. Electrical interlocks on the fan motors are not adequate In the event the fan belt slips, the fan impeller becomes loose on the shaft, or if the fan rotalion is backwards.

7 - 3 . 3 . 2 A f t e r a n a i r sys t em i n t e r r u p t i o n , a v i s iua l inspec- Ibm sha l l be m a d e to d e t e r m i n e if t he c o n t r o l r o o m is safe f r o m the Imza rd of c o m b u s t i b l e dus t .

3 0 0 PRESSURIZED POWER EQUIPMENT ENCLOSURES 49b-$,~

Chapter 8 Pressurized Power Equipment Enclosurel

8-1 Scope.

8-1.1 Chapter 8 applies to equipment enclosures exceeding I~') cubic feet in volmne but not control rooms. For enclosures with 0 volume of 10 cubic feet or less see Chapter 6; for control rnom.q ta~" Chapter 7.

8-1.2 For purposes of pressurizing, electrical power equlp~- ment can be divided into two groups:

8-1.2.1 Pressur ized Equ ipment . Equipment which d0r~ not require air flow for heat dissipation, but which requires pre~ surization to prevent entrance of combustible dusts.

8-1.2.2 Vent i la ted Equ ipment . Equipment, such as mo to~ which require air flow for heat dissipation.

8-2 Requirements for Pressurized Equipment.

8-2.1 The enclosure shall be of substantial noncombustible construction and reasonably tight. Suitable gaskets shall be permis. sible.

8-2.1.1 Precautions shall be taken to protect the enclosure from excessive pressure of the pressurizing supply.

8-2.1.2 Excess pressure relief devices, where required to protect in case of pressure control failure, shall be designed to pre. vent escape of sparks or burning material to a hazardous area when they relieve.

8-2.2 The source of air shall be free of hazardous concentrations of flammable gases, vapors, combustible dusts, contaminants and any other foreign matter.

8-2.3 Piping for air or inert gas supply (if used) shall be protected against mechanical damage.

8-2.4 Combustible dust shall be removed from the enclosure before the power is turned on.

NOTE: For definition of pressurization see 5-3.

6 9 6 - 3 0 PURGED AND PRESSURIZED ENCLOSURES 507

8-2.5 T h e enclosure shall be ma in ta ined under a positive l,:legsure d e p e n d e n t on the specific par t ic le densi ty of the dus t in ,-tt'cordance with the following table, when the power is on :

S•ooCific Particle Density unds per Cubic Foot)

130

Greater than 130

Pressure (Inches of Water)

Not Less Than 0.1

Not Less Than 0.5

NOTE: The density of 130 pounds per cubic foot is slightly greater than that ofsulfur dust, which was one of the dusts used in performing tbe tests on which the values in the table are based. The pressures in the table are based on the assumption that the maximum crack width exposed to falling dust is 1/64 inch wide. The ability of a dust to enter an opening due to the force of gravity against an outward velocity of gas is directly dependent on Its specific particle density.

8-2 .5 .1 I t shall be accep tab le for power to be tu rned on immedia te ly if a pressure as specified in 8-2.5 exists and if the a tmos- ilhere, wi th in the enclosure is not visibly dusty.

8-2 .6 U n d e r no rma l opera t ion in the case of combus t ib le dusts, the ex te rna l enclosure t empera tu re or the t empe ra tu r e of the egress a i r shall not exceed 80 percen t of, and in all cases shall be a t least 50*(3 below the ignit ion t empe ra tu r e (*(3) of the dus t when in tile form of a layer . T h e ignit ion t empe ra tu r e of the dus t l ayer is de te rmined by the p rocedure descr ibed in the U. S. Bureau of Mines Repor t of Inves t iga t ion 5624. (See B2 in Appendix B.) E q u i p m e n t hlstalled in Class I I locations shall be able to function a t full ra t ing without deve lop ing surface t empera tu res high enough to cause excessive d e h y d r a t i o n or g radua l ca rbon iza t ion of any organic dus t deposits tha t m a y occur.

In general , m a x i m u m surface t empera tu res under ac tua l ope ra t - Ing condi t ions shall not exceed 165~ (329 h) for e q u i p m e n t which 18 not subject to over loading, and 120~ (248~ for e q u i p m e n t such its motors, power transformers, etc., which may be over loaded.

NOTE: Dust which is carbonized or is exc~.sively dry is highly susceptible to spontaneous ignition.

8-2 .7 Loss of pressur izat ion shall energize an audib le as well as a visual a la rm. I m m e d i a t e removal of power shall not be requi red in the case of combust ib le dust.

NOTE: A hazard could be created within all cnclusurc only if the pressure should fail, and then it would require an appreciable time for a sufficient dust to filter into the interior of a normally tight power enclosure to be

508 P R E S S U R I Z E D P O W E R E Q U I P M E N T E N C L O S U R E S 496-37

hazardous. Because of this it is not considered essential to remove the power from the equipment upo. n failure of the pressure but only that adequat�9 warning must be prowded to prevent continuing operation without pressure protection. It is essential that the enclosure be tight enough to prevent escape of sparks or burning material.

8-2.7.1 The visual and audible alarm shall be so located that it can be readily noticed and action can be taken.

8-2.8 A warning nameplate shall be mounted on the enclosure. The nameplate shall be mounted in a prominent location and be visible before the enclosure is opened. It shall contain the follow. ing or an equivalent statement :

Enclosure shall not be opened unless the area is known to be nonhazardous or unless the power has been removed from all devices within the enclosure. Power shall not be restored after the enclosure has been opened until combustible dusts have been removed and the enclosure repressurized.

8-2.9 Equipment such as motors and transformers that may be overloaded and that is exposed directly to the dusty atmosphere shall be provided with appropriate devices to detect any increase in temperature of the equipment beyond design limits and to de-energize the equipment automatically. If immediate interruption of power would result in a condition more hazardous than that created by failure to remove the power, audible as well as visual alarms suitable for the area shall be energized.

8-2.9.1 If any internal component has a maximum surface temperature over that indicated in 8-2.6, the surface having this temperature shall be enclosed within a chamber hermetically sealed or suitably gasketed against the entrance of combustible dusts, and of a size which will limit its exterior surface temperature to those specified in 8-2.6.

Exception .No. 1: The warning nameplate shall contain a statement that such conditions exist and that power shall be removedJor - - minutes (period to be determined and specified by the manufacturer to be sufficient to permit unit to cool to safe limit) before the door is opened unless the area is known to be non. hazardous at the time, or

Exception No. 2: The hot component shall be separately housed so that the surface temperature of its housing is below safe limits. This housing shall be pressurized or sealed hermetically or suitably gasketed and provided with a warning nameplate stating that its cover shall not be removed for - - minutes (period to "be determined and specified by the manufacturer to be sufficient to permit unit to cool to safe limit) unless the area is known to be nonhazardous �9 at the time.


8-3 Requirements for Ventilated Equipment.

8-3.1 The enclosure shall be of noncombustible construction with necessary openings limited to minimum practical size and kept 0.~ airtight as possible.

8-3.2 The combustible dust shall be removed from the en- flosure before the equipment is energized and ventilated.

NOTE: For definition of pressurization see 5-3.

8-3.3 The source of air for ventilation shall be free of hazar- (Ious concentrations of flammable vapors, gases, combustible dusts, s and any other foreign matter. Air filtering may be occessary.

8-3.4 Air discharge from the enclosure shall be to an area classified nonhazardous or Division 2.

NOTE: Air filtering may be necessary.

8-3.5 The flow of air should be as uniform as possible within the enclosure so as to avoid, or at least minimize, air pockets.

8-5.6 The flow of air shall be adequate to keep the equipment adequately cooled depending on the operating design requirements.

NOTE: The air required for coofing may be more than that required for pressurizing.

8-3.7 The enclosure shall be constantly maintained at a pres- Aure of at least 0.1 inch of water above the surrounding atmosphere during operation of the equipment unless the surrounding atmosphere is known to be.nonhazardous.

8-3.8 The temperature limits as described in 8-2.6 shall apply.

8-3.9 The electrical circuits of the equipment within the enclosure shall be interlocked with the ventilating equipment so that the equipment will automatically shut down when the ventilating equipment stops.

Exception: I f shutting down the equipment can produce unsafe conditions, an audible as well as a tJisual signal shall be energized so that corrective steps can be taken.

APPENDIX B 4 9 0 ~ 3 9

A p p e n d i x B.

Appendix B is not a part of this .NFPA Standard. It is included for information put- poses only.

B! ASTM D2155-66 (1969), Test for Autoignition Temperature of Liquid Petroleum Products, American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.

B2 Dorsett, H. G., Jacobson, M., Nagy, J., and Williams, R. P., Bureau of Mines Report of Investigation RI 5624, Laboratory Equipment and Test Pro- cedures for Evaluating Explosibility of Dusts, (1960)Bureau of Mines, 4800 Forbes Avenue, Pittsburgh, PA 15213.