sylvania engineering bulletin - germicidal & short wave uv

8/3/2019 Sylvania Engineering Bulletin - Germicidal & Short Wave UV

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Sylvania Engineering

8uIIetin 0-3420981

INFRARED

X RAYS---1

SCHUMANN

100

..j.UV'B.j. UV- AV-C

400

~XTREMEU~

280 315

FA R U V ~ MIDDLE UV+ NEAR UV . 1

10 100 200 300 380

WAV EL EN G TH (N A NOM ET ER S)

ELECTROMAGNETIC SPECTRUM(enlaroement of ullroviolel reqionl

Figure 1

Germicidal and Short-WaveUltraviolet Radiation

layer of the upper atmosphere.

Although the percentage of ultraviolet

energy in sunlight is small, there is still

appreciable energy in the shorter wave-

lengths. The germicidal effectiveness of

sun l ight varies enormously with the

hou r of the day and also with the sea-

sons. Germicidal lamps, however, make

ultraviolet energy available with con-

trollable limits regardless of natural

environmental conditions.

Radiant energy from the sun may be

divided into th ree broad bands: 10ng-

wave or infrared energy such as heat,

which is invisible; visible energy which

produces light and color; and short-

wave energy such as invisible ultravio-

let. As shown in Figure 1, it is the

ultraviolet radiation between 220 and

300 nanometers that is germicidal in

effect; i.e., it destroys bacteria, mold,

yeast, and virus. Practically none ofthe

solar ultraviolet energy below 295

nanometers can reach the earth's sur-

face due to absorption in the ozone

Germicidal Lamps

Germicida I lamps are electrically the

same as fluorescent lamps of corre-

sponding sizes and wattages and

PREFACE

The information presented in this

bulletin is based on research and data

available at the time of publication.

It is, however, beyo nd the scope of this

bulletin to review the entire field of

ultraviolet radiation. Only basic dataand current application concepts will be

discussed.

The end user should always consult

current l iterature for proven application

data on ultraviolet radiation. It is essen-

ti a l t hat the end ussr shoul d read the

precaution notices on the proper appli-

cation of the ultraviolet lamps to insure

adequate safety .

require essentially the same auxi I iary

equipment. These lamps differ phys-

ical Iy from fluorescent Iamps in that

they contain no phosphor and are con-

structed with a special type of glass to

permit maximum emission of germici-

dal ultraviolet energy. The glass used in

ordinary fluorescent lamps filters out

all germicidal ultraviolet energy. The

physical and electr ical characterist ics of

the germicidal lamps are shown in

Table I.

The most practical method of gene rat-

ing germicidal radiation is by passage

of an electric discharge through a low-

pressure mercury vapor. About95% of

the ultraviolet energy is radiated in the

253.7 nanometer line. This is in the

wavelength region of greatest germici-

dal efficacy. Typical spectral power

distri buti on for the tu bul ar germicida I

lamps, showing the principal radiat ion,

is illustrated in Figure 2.



PRIN cIP AL RAD IAT IO N O F TH E G 3O T8 G ERM 'IC ID AL LAM P

IOOr---_,----~----_r----,_----~----~----r_--~r_--_,----~

t i l l : l : l : ~ 2~3_7

~'UI ""... ~ ~ !f46.1 5710O~~~ __ ~--==~_~~m_~~~U~~·····~··'·'LL_ ~ ~·~"~"L·=-~220 260 300 340 390 420 460 500 540 580

WAVELENGTH -NANOMETERS

Figure 2. The mercury line at 253.7 nm accounts for approximately 9()% of the energy

radiated in the 250·600 nm region. The G1Sra and GaTS Germicidal lamps have spectral

power distributions similar to the graph shown.

TABLE I.GERMICIDAL LAMP DATA'

Description G8T5 G15TS G30TS

Rated Power (watts) 8 15 30

Bulb T5 T8 T8

Base Min. Bipin Med. Bipin Med. Bipin

Nominal Lamp Length (inches) 12 18 36

Ncminal-Arc length (inches) 8'12 1'4 32

Rated life (hours) 7500 7500 7500

253.7 nm Output (watts)3 1.4 3.3 8.2

253.7 nm Power Density at One Meter 15 35 80(microwatt per cm')'·3

Approximate Lamp Amperes 0.15 0.30 0.35

Approximate Lamp Volts 57 56 100

1. The life and radiant power of these

lamps are based on operation with bal-

lasts providing the proper operating

characteristics.

The majority of germicidal lamps oper-

ate most efficiently in still air at anambi ent temperatu re of 77°F.These are

the conditions under wh ich the uItravi 0-

let output is measured and tabulated.

The ultraviolet output, and conse-

quentlythe germicidal effectiveness of

these lam ps decreases at tem peratu res

above or below this optimum tempera-

ture. Lamps operating in a room at 40cF

produce only about two-thirds to three-

fourths as much ultraviolet power as at

2. On line perpendicular to lamp axis

through lamp center.

3. 100 hour value.

77°F. If a lamp is cooled by air currents

or by submersion in a liquid, the ultra-violet output similarly decreases. Typi-

cal maintenance of germicidal lamp

types is shown in Fig. 3. While mainte-

nance is a di rect fu nction of bu rn ing

hours, dust collecting on the tube and

reflecting surfaces can easily double

the loss as determined at the irradiated

surface.

100

o 60

"

o 4 5

THOUSANDS Of HOURS BURNED

Figure 3. Typical maintenance charac-

teristics for germicidallemps.

Sylvania Germicidal Lamps

620

Sylvania germicidallemps are available

in three wattages.

A complete description of all three

lamp types is included in Table I. The 8,

15, and 30 watt sizes are designed to

operate with standard fluorescent lampequ ipment of correspo ndi ng size.

Need for Germicidal Lamps

"Fresh air" always has been considered

beneficial. Indoors, however, the air can

be relatively stagnant or have poor cir-

culation, particularly during cold

weather. Also, it can be contaminated

with germs from human beings. Under

such conditions, ai r can be a means

of carrying infectious organisms into

the body.

Bacteria and mold spores in the air can

cause considerable damage to prod-

ucts in a wide variety of industries. This

damage takes the form of spoilage and

contamination. In addition to the costs

resulting from such damage, there are

costs of added maintenance and refrig-

erati on, plus th e ever-present threat to

the health of consumers of the affected

products. Product sanitation obviously

is of vital importance.

Safety Precautions

Itis essential that adequate precautions

be taken in any application of germici·

dallamps. Prolonged exposures to high

intensities of ultraviolet radiation can

cause temporary; but painful inf lamma-

tion ofthe conjunctiva (inflammation of

the outer membrane of the eye), as well

as histological effects in the cornea, iris,

•



and lens of the eye. In extreme cases,

permanent harmful effects can occur.

Reddening or even burning of the skin

(erythema), similar to sunburn, will be

caused by excessive exposu re to uI tra-

violet energy.

The glass used in conventional eye-

glasses affords adequate eye protec-

tion fo r brief exposu reoHowever, care

should be taken that the ultraviolet

energy does not enter the eyes from

the side, nor is reflected into the eyes

from the back side ofthe glasses.

Clear plast ic face shields are available

to protect the face. Welder's shields

sometimes have been used. Such pro-

tection should include the ears, par-

ticularly when the wearer may be

exposed to a number of lam ps, It is well

to remember that when one is exposed

to short-wave ultraviolet energy; the

effects may not be felt until several

hours afterward. Likewise, individualsvary greatly in their sensitivity to radia-

tion. Children, for example, are fre-

quently more sensitive to ultraviolet

than are adults.

Where the conce ntration of germi cidal

energy is especially high, protection of

hands and arms may be necessary.

Clothing and gloves will generally pro-

vide adequate protection.

Safe exposure l imits for ultraviolet ger-

micidal irradiation have been set by the

American Conference of Governmental

and Industrial Hygienists."

The general practice based on these

limits is given in Table II. Exposure is

roughly the product of irradiat ion

(microwatts per square centi meter) and

time. The safe exposure time at 2% feet

from a bare G30TB germicidal lamp is

about one minute based upon this

practice.

Table II. Recommended maximum safeexposure to Germicidal Ultraviolet"

Exposure

P er D a v8Hours4 Hours1 Hour10Minutes1 Minute

Irradianee J.l.W em-'0...2

0. 4

1. 6

10

10 0

"Based onthe 253.7nm radiation of thegermicidal lamps.

The near ultraviolet region ofthe spec"

trum in the vicinity of 330 to 380

nanometers is used for "black light"

effects. This radiat ion does not produce

erythemal effects. Note that there are

extreme exposure limits on all parts of

the Ultraviolet, visible, and infrared

regions of the spectrum. (See Refer~

ence 13 for a discussion of exposure

limits).

Exposure Time

A lethal exposure period of an organ-

ism is determined by its susceptibili ty,

the wavelength of radiation, the density

of the radiant flux (watts per unit area),

and the time exposure. Table I I I gives

the amount of 253.7 nm energy density

in microwatt-seconds per square cen-

t imeter to destroy 90 percent of va rious

common microorganisms.

The germicidal effect iveness is pro-

portional to the product of intensity

times time from one microsecond to a

few hours.

TABLE III. GERMICIDAL ENERGY

REQUIRED TO DESTROY COMMON MICROORGANISMS

Organisms

BacilIusanthracis

S. enteritidis

B. megatheriumsp. (veg.)

B. megatheriumso. (spores]

B. paratyphosusB. subtilis

B. subtilis spores

Corynebacteriumdiphtheriae

Ebenhella tvphosa

Escherichia coli

Micrococcuscandidus

Micrococcussphaeroides

Neisseriacatarrhalis

Phytomonastumefaciens

Proteusvulgaris

Pseudomonasaeruqlnosa

Pseudomonasfuorescens

S. typhimurium

Sarcinalutea

Ssratia marcescens

Dysentery bacl I I i

Shigellaparedvsenteriae

Spirillum rubrum

Staphvlococcus albus

Staphvloccccus aureus

Streptococcus hemeIytlcus

Streptococcus lact is

Streptococcusviridans

YeastSaccharomycesellipsoideus

Saccharomycessp.

Saccharomycescerevisiae

Brewers'yeast

Bakers' yeast

Common yeastcake

Mold Spores

Penicillium roquetorti

Penicillium expansum

Penicillium digitatum

Aspergillusglaucu5

Aspergillusflavus

Aspergillusniger

Rhizopus nigricans

Mucor racemosusA

Mucor racemosusB

Oosporalactis

3

Green

Olive

Olive

Btuishgreen

Yellowish green

Black

Black

White gray

White gray

White

Energy

(I'w'S8C/cm2)

4520

4000

1300

2730

3200

7100

12000

3370

2140

3000

6050

10000

4400

4400

2640

5500

3500

8000

19700

2420

2200

1680

4400

1840

2600

2160

6150

2000

6000

8000

6000

3300

3900

6000

Color

13000

13000

44000

44000

60000

132000

111000

17000

17000

5000



Measurement of UltravioletRadiation

An ultraviolet meter developed by

Ultra-Violet Products, Inc., measures

253.7 nm germicidal radiat ion direct ly.

Visible light is not measured with this

meter. Measurements are calibrated in

microwatts per square centimeter

(p.Wlcm2). Figures 4A and 48 illustrate

the meter. International Light, Inc., also

manufactures and markets instruments

that measure the germicidal region of

the spectrum (see Fig. C.) . As lamps

age, it is important to know when to

replace lamps that have fallen below

the standards normally required for

effective germicidal action. Since it is

impossible to observe when this point

occurs by looking at the tube, the use of

a meter becomes imperative.

Figure 4A. TheBlAK-RAY~ UltravioletMeter is calibrated to measure short waveintensity in microwarts per squarecentimeter.

Applications

The more common applications of

germicidal lamps fall into two broad

classifications, personal protection andproduct protection. Personal protection

is the irradiation of the air in a room for

the purpose of protecting the occu-

pants from airborne infectious dis-

eases. Product protection isthe use of

ultraviolet radiation in areas where

food, pharmaceuticals. and other prod-

ucts are processed and stored to pre-

vent contamination and spoilage by

molds or other microorganisms.

Figure 48. Detachable sensor cell makes readings asclose as a one-quarter inch fromthe irradiated surface. The picture shows the measurement of short wave radiation onsubstances in laboratory dishes.

Figure 4C . The IL570 Germicidal/Erythemal Radiometer is an instrument specificallydesigned for measurements in the ultraviolet portion of the spectrum.

Air Irradiation in Heating and Air-

Conditioning Ducts: Germicidal lamps

are used in heating and air-conditioning

du cts to reduce the qua ntity of live bac-

teria and to make the air passing

through the ducts equivalent. insofar as

possible, to outdoor air in terms of free-

dom from live bacteria. The design of

any system for air steri lizat ion depends

upon the sou rces of the conta mination.

the type of space, and the kind of occu-

pancy of the space. The requirements

fortheaters, restaurants, and stores are

quite different from those for sch 001s

4

•

•

•



and those for hospital wards and oper-

ating rooms.

Ai'r being brought into a room or build-

ing can be sterilized readily by properly

placing lamps in the air-handling duct

work. The size and shape of the duct,

the ultraviolet reflection characteristics

of walls, and the number and arrange-

ment of the lam ps determ ine the effi-ciency. The essential featu re of the

geometry is to insure that all the baete-

rta passing through the duct are sub-

jected to sufficient bactericidal

irradiation.

A simpl ified formul a for caIculati ng the

number of G30T8 germicidal lamps in

such ducts for air temperatures of

6 5 D-70°Fis as follows:

N = CFM. where20xd

N =approximate number of G30T8

lamps required

CFM = cubic feet of air per minute

d =smaller cross-sectional

dimension of duct in inches

More accurate calculations which may

be required for large installations

require an allowance for air tempera-

ture and humidity. Fora relative humid-

ity of 60% or less, if the duct a Ir

temperature is less than:

60°F - increase the number of lamps

1% times.

50°F- increase the number of lamps2% times,


4times, and


6 times.

At higher relative humidities, twice this

number of lamps should be used.

The basis of th is form ula is a 90% deac-

tivati on of the standa rd test micro-

organism. Eschericia coli. It is assumed

that the duct walls have zero reflectance

to 253.7 nanometer energy.

Example

How many G30T81amps would be

required for 10,800 CFM of air carried

by a 60- by 75-inch duct?

Air temperature is 60°F,relative humid-

ity 55%.

N = 10,800 1V :20 x 60 x z

N = 13..5or 14 lamps

AI,though there are a number of ways of

installing germicidal lamps in air ducts,

the best compromise is to place the

lamps lengthwise on the duct wall. The

lamps should be mounted on4-to &-

inch centers. and grouped in the center-

half of the duct walls, away from the

corners (rectanqutar ducts). Where

mechanical conditions require it, the

lamps may be mounted end-to-end

alonq the duct. Several methods of

installing germi.cidallamps in air ducts

are shown in Figures 5A, B, and C.

TYPICAL METHODS OF INSTALLING GERMICIDAL LAMPS IN AIR DUCTS

//

Figure5A.

Since germicidal lamps must be kept

reasonably free of dust for best results,

they must be accessible for cleaning.

This requirement can usually be met by

the use of hinged panels on the sides or

the bottom of the ai r duct

In large ducts, germicidal lamps may be

assembled in vertical frames,like rungs

of a ladder, supported in the center of

the chamber in whatever series or mul-

tiple arrangement bestfits local condi-

tions and also provides access for

cleaning and replacement.

Figure5B.

In very large ducts where the ai r speeds

are relatively low, the tubes should be

placed in such a man ner that the aver-

age distance measured perpendicular

from the tubes to the duct walls is max-

imum. The direction of airflow is not

considered in this situation.

It is sometimes desirable to combine

the germicidal treatment of ai r with

humidifying, filtering, and heating. In

such cases, if possi ble, the lam ps

should be placed at a point of average

air tern peratu re, away from th e very hot

5

12'

FigureSC.

air ar the very cold air .Further, th e

lamps shou Id be placed after the air fil-

tering,. but before the humidificati on

stage of the system. Placl ng the lamps

after filtering reduces lamp mainte-

nance; placing them before humidifica-

tion increases germicidal effectiveness,

since humidification tends to increase

the resistance of bacteria and other

microorgan isms to germ icida I energy.

Irradiation of Air and Room Surfaces:

Wa,rm alr in hospital rooms, offices,

school rooms, cafeterias, and hallways



normally rises toward the ceil ing. The

convecti on cu rrents force cooler air

down along the walls to the floor where

the air is warmed and again rises. The

presence of such heat sources as radia-

tors, floor lamps. and even human

beings generally aids in the convection

of air.

Due to this air movement in a room,

germicidal lamps can be installed on

walls, slightly above eye level, and still

be germicidally effective. Air irradiated

near the ceiling is caried by convection

to the lower portions of the room with-

out exposing human occupants to

direct lamp radiation. The effect is simi-

la r to excha nging the air in the room

with air from the outside.

Germicidal fixtures may be either

recessed in the wall or surface-

mou nted on the wa II. These two meth-

ods are illustrated in Figures 6 and 7.

Two types of fixtu res may be used gen-

erally in occupied rooms: open and

louvered types. Diag rams of these two

types are shown in Fig ures 8 and 9.

INSTALLATION OF GERMICfDAL FIXTURES FOR AIR AND ROOM SURFACES IRRADIATION

Figure 6. Recessed in the wall. Figure 7. Surface-mounted on the wall.

TYPES OF FIXTURES USED IN OCCUPIED ROOMS (TYPICAL PLACEMENT)

12ft.

Figure 8. Open fixture.

The open type fixture is satisfactory for

rooms where the ceiling is at least 91;l

feet in heig ht and where the oceu pants

do not stay fo r more than eight hou rs at

a time. Where ceilings are less than 9%feet high and where the occupants

remain for prolonged periods as in hos-

pital wards and nurseries, the fixtures

should be louvered.

Any plan to install germicidal lamps

for upper-a ir i rradiati on must take into

account the ultraviolet reflectance

characteristics of the ceiling. In areas

with painted "white-coated" plaster

7ft.9ft.

6%ft.

Agure 9. Louvered fixture.

6

TABLE IV.

Recommended Number of 15- or 30-

Watt Germicidal Lamps For Irradiation

of Upper Air In Rooms IOpen-front or

Louvered Fixtures)

Room WIdth_III.)

1~13 14-18 19-24 211-3132·31

Room

L.. gth "'mp SIze1Ft. ' 15W lOW 1SW :;oW 15W lOW 30W 30W

10-13 2 1

14-1,8 2 1 3 1

19-24 2 1 3 1 4 2

25·31 3 1 4 2 5 2 3

32·39 5 2 3 3 4 5

40-48-3 3 456

49-58-4 4 567

ceilings and walls, an exposure of more

than two to three hours may be unsafe

unless proper finishes are used. The

"white-coat" should be painted with

either a water-solubte or an oil peint,

The number of lamps recommended in

open-front or in louvered fixtures for

the irradiation ofthe upper air is given

in Table IV.This data is based on 90%

upper-air deactivation of a standard

microorganism, Eschericia coli. An

annual fixture cleaning and lamp

replacement is assumed.



Product Protection

Although germicidal radiation was dis-

covered 150 years ago, it developed

from a laboratory curio to an engineer-

ing tool on'ly during the last quarter of

a century.

Germicidal applications for product

protection are numerous. They rangefrom the simple application of germici-

dal energy on products stored in

storage cabinets to the i rradiati on of

harmful organisms in liquids. New

fields for the use of germrcidallamps

exist wherever products designed for

huma n co nsu motion are ma nutac-

tured, or wherever a health hazard

exists due to bacterial conta rni natl on.

All reflectors for industrial applications

of germicidal lamps should provide

60% to 70% reflectance for energy at

253.7 nanometers ..Materials should be

of highly polished metal surfaces such

as stainless steel, polished Alzak alumi-

num, decorative chrome plate, or

l.uriurn". All fixture parts should be

specially processed for resista nce to

acid or alkal ine fumas and m oistu re

(See Figure 10). Figure 11 i llustrates a

simple fixture that can be used to pro-

vide direct germicidal irradiation. The

relative radiant intensity is shown on a

polar graph.

Airborne microorganisms such as bac-

teria, yeast, and mold spores, cannot

thrive onthe surfaces of foods, l iquids,

and pharmaceuticals if these surfaces

are direct ly irradiated with sufficient

amounts of ultraviolet energy. Mold

spores,i n general, are more resista nt to

ultraviolet energy than airborne bacte-

ria. Hence, high intensities ofgermici,

dal energy are requ ired for good

control. If mold has already formed,

ultraviolet energy cannot eliminate it.

The food indu stry represents awide

and varied field of application ..Non-

food products also offer a considerable

number of applications.

List of Products Protected by Germici-

dal Lamps:

Food Products

Sugar: granulated, syrups

Beverages: fru it ju ices, bottl ed dri nks,

beer, wine

Dairy Products: milk, cheese

Baked Goods: bread, cakes

Fruit

Nuts, Pies, Pickles

Vinegar

Veg.etables

Water

Meats: processing, packaging, storing

(coolers)

Non-Food ProductsBiologicals: vaccines, serums, tox-

aids, ointments

Packaging

Instruments: medical, dental, barber

equipment

Textiles

Bottling Operations

Storage Cabinets

Paper Products

Industrial Liquids: oils, dyes

Glasses.

Toothbrushes

Figure 10. Fixtures for germicidal lampsshould be of highly polished surfaces, andresistant to acid or alkaline fumes andmoisture.

A LZAK AL UM I "! UM 'RE FLECTOR A"!O T - 8 LAMP

1~L5·'-

R ADIA NT IN TE NS ITY - % O F BARE LA MP

RADIANT I"!TENSITY - 'f. OF ,BARE LAMP

PII,RALL:EL 0- PER PENDIC ULAF!TO LAMP TO LAM P

Figure 11. This illustrates atypical distribu-tion curve of a bare T -B germicidal lamp inan Alzak aluminum reflector.

Ultraviolet Sanitation

There are three general methods for

ultraviolet sanitation thet can be used,

either separately or in combi nati on:

7

1. Upper-air Irradiat i on:

This helps to provide an area.o f irra-

diated air in the upper portion of the

roo m. Normal ai r currents diIute the

lower contaminated air with the

purified air to maintain a low bacte-

rial count at the breathing level.

Upper-air irradiation permits contin-

uous, safe occupancy of a room (See

Figure 1 '2) .

2. Barrier- Type Irradiati on:

This type of germicidal installat ion

provides a narrow beam of germici-

da I energy that ca n be di rected to

prevent the passage of live micro-

organisms from one place to

another. This method is illustrated

in Figure 13.

3. Direct Irradiation:

This is the most efficient way of dis-

infecting', not only the air of a room,

but also the exposed solid surfaces.

The Iimitation of this method is that

germicidal intensities are also irr itat-

ing to the skin and eyes of both

individuals and animals in the room.

It is necessa ry to tu rn the germicidal

lam ps off when workers a'Fean rou-

tine duty or to protect them by

goggles, masks, gloves, or other

means. Germicidallamps are used

for the di rect irradi ation of va rious

biological l iquids, such asserums,

plasma, vaccines, toxins, etc.

figure 12. The principle of upper-air irra-diation is shown in a veterinary hospital.Upper air in the zone lrradlated by germici-dalIampsls disinfected and displaceddownward, diluting microorganism con-centration at the lower level.



Figure 13. Combination of upper-air andbarrier-type irradiation that disinfects theair in the hospital service room adjoiningth e nurserv It consists of a 2-lamp fixtu rethat helps to prevent the circulation 'of air-borne microorganisms into the nursery.

Sanitary Environment

Germicidal radiation can provide and

maintain sanitary condit ions for objects

previously made sterile. An 8-watt ger-

micidal lamp, for example, can be used

effect ively in storage cabinets which

have a volume of one cubic foot or less,

such as those used for storing barbers'

supplies, babies' bottles, drinking

glasses, and medical and dental instru-

ments (See Figure 14). Similarly, a

15-watt germicidal lamp will provide

sufficient ultraviolet radiation for a stor-

age capacity of 8 cubic feet and a30-

watt lamp for 20 cubic feet or less.

These systems provide effective inten-

sities of from 10to 100 times those

Figure 14. Typical sanitary storagecabinets.

produced in the irradiation of air for

room ventilation. They are adequate for

almost instantaneous destruction of

bacteria introduced by the opening and

closing of the cabinet door. Lamps

should always be positioned directly to

the rear of the cabi net door so that

when the door is opened, the incoming

air will be intercepted by the energy

from the lamps.

Meat Storage

Freshly slaughtered beef must be

"hung" in cold storage for a short

period of time to break down the con-

nect ive tissue changing it to a gelati-

nous mass. This change, known as

tenderiz ing, is due to enzyme act ion

and can be enhanced by increasing the

ambient temperature. The cooler may

be operated as high as 45°F pOe) using

a sufficiently high relative humidity toreduce dehydration losses. Tempera-

tu res of 45°F ar above are conducive to

the acceleration of the tenderizing pro-

cess but, at the same time, will also

promote growth of molds on meat. The

infected parts must be cut away, and

this means a severe loss to the butcher.

Properly installed germicidal tubes not

only reduce contamination of stored

meat by airborne bacter ia, but they

reduce the bacterial growth on meat

surfaces equivalent to a 10°Flowering

of temperature below the 40"F - 45°Frange. This retardation of bacterial

growth is Significant since losses due to

tr imming, drying out, bacterial slime,

and mold can range as high as 15per-

cent. Likewise, when aged meat is

stored, the use of germicidal lamps will

resu It in a redu etion of spa ilage tri m.

To obtain best results, install one 15-

watt germicidal tube to cover 40 square

feet of floor area, with a minimum, in

case of small storage spaces, of two

lamps. Ultraviolet radiation must be

directed on the meat surface, as well as

on sur faces of the cei ling, wa lis, and

floor. These germicidal lamps should

operate cont inuously. For worker pro-

tection, a switch should be installed to

turn off the lamps when the storage

door is opened and while workers are

in the storage room.

Slight air circulation is important. A

small fan in the upper portion of the

cooler wil l provide air circulation

8

through the whole storage room. The

fan should not be directed on the ger-

micidal tubes because cool circulating

air will reduce the ultraviolet output of

the tubes.

lf reduced germicidal radiation is a

problem when the am bient tem pera-

ture is low, the germicidal lamps can be

jacketed with tubes ofthe same glassused to make the lamp. This jacket

restores normal operating lamptem-

perature and jacketed tubes have two to

three times the germicidal ultraviolet

output of an unjacketed tube at the

usual meat storage temperatures.

In the holding rooms a common usage

is one 15-watt germicidal lamp for each

40 square feet, or one 30-watt germici-

dallamp for each 100 square feet,

above the monorail system. The usual

mounting heights are 12feet; a typical

arrangement is illustrated in Figure 15.

For cooling rooms, use 15watts per 40

to 60 square feet, or 30 watts per 120 to

150 square feet of area. The lamps

should be mounted to irradiate as

much of the meat su r faces as possi ble.

Figure 15. Sanitary storage of meat.

Two types of mold are mostly responsi-

ble for the damage to the meat, namely

Sporotrichum carnis which produces

long white threads, and the Mucors

together with Thamnidium which forma greyish-white growth known as whis-

kers. Mold formation is also encour-

aged by the high relative humidity (r.h.

85 to 90 percent) wh ich is a desi rable

condition to prevent evaporation of the

moisture and shrinkage of the meat.

Mucors and other fungi are readily

destroyed by the 253.7nm radiation. It

must be borne in mind that careful

handling, cleanliness, low tempera-



tures, and similar. methods are preven-

tives of proven value.

Ultraviolet radiation of bactericidal

wavelengths is purely surface-effective.

Its penetrating power is negligible. In

the food industry, surface sterilization is

important in the endeavor to prevent

the infection not only of foodstuffs but

also of machines and tools.

There is little possibil ity of introducing

flavor or organoleptic changes as a

result of ultraviolet irradiation except

with fats and oils. This is due to the

generation of hydrogen peroxide H20,

and its strong oxidizing action.

Bakeries

Mold contamination is a major problem

in bakeries. Humidity and the constant

accumulation of fine dust makes it diffi-

cult to prevent mold formation even

with periodic cleaning. Ultraviolet irra-

diation of walls and ceilings to inhibit

spore formation with localized treat-

ment of the conveyor and bakery

products has proved effective. Germici-

dal irradiation of the walls and ceili ngs

in the fermentation room can reduce

the need for frequent cleaning of those

surfaces and thus reduce maintenance

costs. One 15-watt germicidal lamp is

commonly used for every 30 to 40

square feet of ceiling area or one 30-

watt germicidal lamp may be used for

every 75 to 100square feet of ceiling area.

Biological Supplies

Due to ever-i ncreasing demands for

biological supplies, pharmaceutical

houses use large volume testing pro-

cedures and mass production. These

large-scale operations demand

increased sanitary control measures

to insure that products are free of con-

taminating organisms. Germicidal

lamps play an important part in attain-

ing sterile areas for the production and

packaging of sterile material and in pro-

tecti ng laboratory workers from infection.

tion require an addit ional multiplying

factor of about 5, so that the exposures

to produce any given disinfection of

water are 40 to 50 times greater than

those required for dry air.

Absorptive liquids decrease the ger-

micidal intensity logarithmically with

the distance from the lamp. Minute

traces of iron compounds and organiccompou nds in liquids decrease the

transmission of germicidal energy.

Compounds of calcium, magnesium,

sodium, and aluminum sulfate in a liq-

uid increase the transmission of ger-

micidal energy, unless two or more of

the compounds form a precipitate.

In each specific liquid, there is a critical

dis ta nee fro m th € I germicida I lamp at

which 90% ofthe ultraviolet energy has

been absorbed. Ten percent afthe

energy, or less, remain to be transmit-

ted to the l iquid beyond that distance.

The distance for a 90% absorption,

called the "effective depth of penetra-

tion" may vary upward from a few

thousandths of an inch in milk, and

serums, or one-tenth of an inch in

wines and syrups, to five inches

through drinkable water of high trans-

mission and 10feet fa r some disti lied

water.

The design of systems depends upon

the particular requirements. Immersion

of the lamp directly in the water is un-

satisfactory because of the decrease in

ultraviolet output due to the cooli ng of

the tube by the water. When the lamp

has to be immersed in the water, it

shou Id be insta lied insi de aqua rtz tu be

for satisfactory ultraviolet transm ission.

This avoids the cooling and consequent

loss of lamp efficiency which would

result if the water were in contact with

the lamp wall. It also makes the clean-

ing and replacing of the lamp easier.

There must be a water-tight bond

between th-e enveloping tube ends and

the lamp ends for satisfactory

operation.

However, to avoid the extremes of

water temperatu re, the germicidal

lamp may be placed above the water

surface and partially enclosed in a

reflector. In this system, about 25% of

the ultraviolet output of the lamp

should reach the water surface direct ly;50% to 75% of the balance comes from

the reflector.

The basic techniques for purifying

water may be classified by the way the

germicidal lamps are used (immersed

or offset) and by the water system

(pressure or gravity). They combine

in three basic types: IP (immersed-

pressure), OP (offset-pressure), and OG

(offset-gravity) as shown in Figure 16.

IP

Figure 16. BASIC TYPES OF I '/ jI .TER DISINFECTING DEVICES

ALZAK

ALUMINUMREFLECTORSterilization of Liquids

Microorga nisms absorb consldera bly

less germicidal radiation when in very

humid air, or in water, than when in

very dry air. Waterborne E. coli, for

example, may require an 8 to 10times

greater exposure for a given kill than

dry airborne bacteria. The ultraviolet

absorption of water and mini mu m

provisions for circulation during irradia- Figure 17. SUGGESTED DIMENSIONS AND RATIN G S OF SMALL GRAV ITY TYPE WATER DISIN FEe TORS.·

9



An Alzak or Lurium aluminum reflector

on the upper cylindrical surface of the

chamber nearly doubles the germicidal

radiation throughout the lower half of

the chamber.

Figme 17 illustrates practical dimen-

sions for the gravity flow disi nfectors

wh ich C C I n be used with the 8. 15. and 30

watt lamps. They will provide 90% dis-infection, (with a 100% factor of safety)

of drinking water, transmitting 253.7

nanometer radiation effectively to a

depth of at Ieast 5 inchesif these rates

of flow are nat exceeded: GaTS, 100

gallons per hour; G15Ta, 200 gallons

per hour; and G30TB, 500 gallons per

hou r: . Where a com pact and powerful

source of germicidal energy is required,

it is suggested that quartz tubular high

intensity mercury lamps be used.

The continuous-flow capacity ratings

of the three basic techniques are tabu-

lated in Table V.The effective depth of

penetration of Table V determined in a

laboratory, fixes the maximum depth of

water to be processed in any device.

The water may otherwise be distributed

around or under the germicidal tubes in

any conven ient way that wi II intercept

all the energy from the tubes and

reflectors.

Antiquing Bottles

Some antique hobbyists use germicidallamps to produce old apothecary glass.

Exposure of preserve-type jars and bot-

tles to germicidal radiation can change

the COIOf of the gIass and age the bottle.

Certain impurities in the glass cause the

color to change. All glasses do not

col Of, but exposu re to the germicidal

energy for a few hours will i ndi cate

whether color changes will take place.

Safety precautions must be adhered to

at all time (See "Safety Precautions"],

Calculati.ons in the UltravioletSpectrum

Many of the techniques and equations

that are fa miliar in illu mi nati on engi-

neering for lighting calculations can be

used for the ultravi olet portion of the

spectrum. The various geometric

equati ons are basic to aIIradi ornetric

calculations. Photometry parallels

radiometry and is a special case of

TABLE V . 90% Disinfection of Liquids - Gallons per Hour"

No. 01G8TSt 2 3

No. of G15TS' 2

No. of G30:T8t 2 3 5 i 8 10 13 16

42 83 200 400 600 800 1000 1200 1600 2000

2 84 167 400 800 1200 1600 2000 2400 3200 4000

3 124 250 600 1200 1800 2400 3000 3600 4800 6000

~ 4 167 334 800 1600 2400 3200 4000 4800 6400 8000

0 ' < : 5 208 416 1000 2000 3000 4000 5000 6000 8000 10000OJ. J : : : . c

6 250 500 1200 2400 3600 4800 6000 7200 9600 12000'.5.-

'"I

7 292 584 1400 2800 4200 5600 7000 8400 11200 14000c c

'"0 8 333 666 1600 3200 4800 6400 8000 9600 12800 16000; ; ; > ' ~

.~ ro9 375 750 1800 3600 5400 7200 9000 10800 14400 18000

{,) . : : ." '" 10 417 834 2000 4000 6000 8000 10000 12000 16000 20000:. cw il)

12 500 1000 2400 4800 noo 9600 12000 14400 19200 24000,

15 625 1250 3000 6000 9000 12000 15000 19000 24000 30000

18 750 1500 3600 1200 10800 14400 18000 21600 28800 36000

24 1000 2000 4800 9600 14400 19200 24000 28800 38400 48000

For cu. It. per hour, multiply above by 0.13368; lor cu. in. per hour, by 231.0; for cu. in. per

mi nure, by 3.85.

tAllows lor 65% 01 bare lernp eff ic iency for lam p and ret lector combinat ion.

• Based on standard microorganism. E. coli .

radiometry. In the specific case of pho-tometry, terms from the luminous

system are used. The corresponding

radiometric terms can be used di rectly

in the same equations. Table VI gives

the basic quantities using standard

symbols ..Many other symbols and

units have been used in the past.

When considering light, the radiant

power (watts) is weighted, wavelength

by wavel.ength, usi ng the spectral sen-

sitivity of the eve, i.e., the luminous

spectral eff iciency function. If the

appropriate consta nt of proportional ityis used, the result is the lumen. In con-

siderinq the ultraviolet portion of the

spectrum, one can weight the radiantpower by an appropriate factor for each

wavelength, e.q, the erythemal.

response will! lead to the unit of E-viton.

Alternately, one may work di rectly with

the power at a particular wavelength or

with the power in a particular wave-

length band.

Several units of length are commonly

used for wavelength. These include:

the nanometer (nm) equal to 10-9

meters, the micron tu) equal to 10-5

meters, and the angstrom (A) equal to

10-'0 meters.

Atmospheric attenuation over dis-

tances of several meters can be entirely

TABLE VI. FUNDAMENTAL QUANTl~IES

R.d iometric System Photometr ic (Luminous) System

Symbol Oefining Equ.tion au.ntitY' Unit Ou an tll.,. Unit

0 Radiant energy joule luminous energy lumen second

dOih "'~- Aadia ... flux watt Luminous f l 1 u : x lumen

dt

dd> Incidenl tad i ant wall meter-2 Incident luminous fumen 100t-2

E E-- ftux density Ilux density Ilootcandle)dA

(irradiance! (illumination)

dih

Emitted radiant watt meter-2 EmiUed luminous lumen 1001-2

M M~- I Iux den sit I' Ilu~ densitydA Iradiant exitance] [lu minous exitance)

d d > b

,1- Ra.diant intensity watt luminous intensity lumendw steradian -I steradian-1

(cand'el~)

d'd>,

l l - Radiance watt mete r -~ lu mina,nce' lumen 100t-2dAdwcoc6 steradia n _, steradi,m-'

(candela foot -2)

Notes:a l The pref ixes "radiant" & . "luminous" of ten a,re omitted if no confusion will occur.

bl ru is the sol id ang le 01 a di fferent ia l Source e lement expressed in steradlans.

ci H is the anqle between a line of sight & . the normal to area dA.

d) See Reference 6 lor a complete discussion 01 th i s term & . l ts var ious un its . .

10



•

neglected for wavelengths above 300

nanometers in the ultraviolet. It

becomes appreciable below 300

nanometers and increases rapidly with

a decrease in wavelength. Atmospheric

effects should be considered, even for

distances of less than one meter, for

wavelengths below about 230 nanome-

ters. At a wavelength of 205 nanome-

ters, a typical value of atmospherictransmittance for a one meter path

might be 0.1. Absorpti on and scattering

are the two basic mechanisms of

attenuation. At a given wavelength, the

attenuation can easily vary by a factor

of 100 due to atmospheric conditions.

The reflectance of metals is dependent

on the method of surface preparation,

impurities, surface conditions, and

other factors. The difference for metals

between polished bulk material and

evaporated surfaces can be quite large.

Figure 18 shows typical values for spec-

ular surfaces. The high value shown for

aluminum is obtained for deposited

films in vacuum. Even avery brief

exposure to the atmosphere will signifi-

cantly reduce this value. Also, Figure 19

ill ustrates the typica I reflectance of van-ous materials in the germicidal region .

Transmittance values of materials are

dependent on sample thickness since

absorption losses vary exponentia Ily

with thickness. Figure 20 shows typical

transmittance curves of several com-

mon materials. The sample thicknessesare indicated, and surface ref lection

losses are included. The curves for

materials such as qua rtz vary consider-

ably with the particula r type. Transm it-

tance values for glass often vary

sig nifica ntly with tem peratu re; th is

effect is important for fi lters operating

near hot sources.

Measurement accuracy in the ultravio-

let, particularly at the shorter wave-

lengths, is considerably less than found

in the visible spectrum. Also, the optical

properties of the var ious system com-

ponents are not as well known for the

ultraviolet reg ion of the spectru m as for

the visible spectrum. Consequently,

approximate calculations, based on

typical data, often are adequate. Exam-

ples of typical calcu Iati ons are given

below. Several methods are possible

for solvl ng each of the problems. The

techniques used were selected to dem-

onstrate several types of calculations

TYPICAL REFLECTANCE IN THE GERMICIDAL REGION.

THE VALUE CAN VARY OVER A CONSIDERABLE RANGE

DEPENDING ON MATERIAL PURITY. METHOD OF PREP--ARATION, SURFACE CONTAMINATION AND FINISH,GEOMETRY OF INCIDENT AND COLLECTED RADIATIONEll: ...

1.0-:tzVIf)

NO.8

wuzs 0.6uw_J

u,Wa:

w

!; i::!x 0.2oa:a . . ., 0 . .

e X

Agure 18.

ENHANCED ALUMINUM

MAGNESIUM OXIDE

CALCIUM CARBONATE

'AlZAK' ALUMINUM ALUMINUM PAINT

WHITE PLASTER

CONSTRUCTION ALUMINUM

NICKEL

BLEACHED COTTON

COPPERWHITE PAPER

CHROME

SILVERSTAINLESS STEEL

LIG HT WALL PAPER

LINEN WOOD

BLEACHED WOOLo

e~ »>>:..~-r.-t.-,,-/ . / 0

~ . / . J - - - - - - -.4 . : . 1 - - - :

" .:-

r'~ ·-'-l-·~_._. ~ -, :

'.J

.6

WAV E : I , . . £ " " (HH -NANOrr.i(U:FII~

A ~ A I. U MI N Ui tl l

E !I - ALlAK FINi$H ALUMINUM

C & CHROIYIU i a I !

0- sn.VER

£- "ICI([1..

F- STAUu_ESs :nEEl .

Figure 19. Reflectance Values of CommonMaterials

and are not necessarily the most di recto

These examples are analogous to

lighting calculations as described in

standard textbooks on illuminating

engineering.

11

WHITE OIL PAINT

TYf lICl I.L. TRANSMI 'TTANI ;( CUR"~S Of COMMON MAl£FUAI.S

~OO=--~2'~O--~~~~~~~--~'OO

WitVEL.fN(1T ....- NA~MEtERS

. il l - W~HOOW GlASS. 10lNCk'I

&- P 'fRf )! 111774-, Imm

C - PY RE ::W :-g.14 i. Im m

0- CLEAR FUS£C OUAR'Tl, lem

E - DiSrlLL£O WATER, "6 IlfCH

F- POUSTYR£NE FI l. ", ,0066 I~CHINi ITIA l

G - POLYSTyRENE F ILM . , 0011 58 I tf CH - A rTER 1M HOUR

EXP'OSU ,. E TO S -j LA '- IP AT 6 INCH O ls tAHCe:

H- MY.Ali iI ~50AI. ,1!""1rI

Figure 20. Typical Transmittance Curves ofCommon Materials.



EXAMPLE 1: Determine the 253.7nm irradiance produced by a G8T51amp (5/8" diameter) for points A and B.

a) From Table I, the radiant flux at 253.7nm

M 0.059 . ~ IL = = --- = 0.019w In-' sr "

1T 7T

~ " " - 1 GeB_ L · ~ 1.=~

I .s"

l_l

r/ > =1.4w

b) The lamp can be approximated as a long cvlindrical radiator whose radiantexitance is

M =. !E_= 1.4w 0.059w in-2

A 1T x 5/8" x 12"

c) Assuming this is approximately Lambertian,

6

d) Since 12" > 3" > 5/8", the semi-infinite Lambertian strip is a good approximation for point A.

E'IT L ( width) 7T x 0.019 5/8" 0003 . -2 (48 -2)

A= = --= lwm or= O/Lwcm4 distance 4 3"

e) For point B, the inverse square law will be within a few percent for a Lambertian strip since the distance is 4 times the

maximum di mension. The radiant intensity in the direction of point B is

1= Lx Ap'oiected = 0.019 x (518" x 12") =0.143wsr-1

f) Finally, with the inverse square law we find

Many refinements could be made in these calculations to account for end effects, finite length of lamp, etc.; however, this

accuracy usually is not warranted.

EXAMPLE 2: Aparabolic trough reflector 12 inches long and with a focal length of 1-1/2 inches is located above the lamp of

Example 1.The reflector is specular Alzak aluminum, and the lamp is located along the focal line of the reflector.

What is the 253.7nm irradiance at Point B?

a) A quick check shows that point B is past the minimum inverse square distance for the reflector. Therefore, point B "sees" a

reflector radiance equal to the lamp radiance times the reflector reflectance (0.6 from Figure 19).

Lrel' = 0.019 x 0.6 = 0.0114win-2sr-1

b) If the reflector subtends the solid angle dw at point B and the solid angle is small, the reflector produces an irradiance of

(6" - 5/8") x 12" .Es = L,e!'dw = 0.0114 = 319 x 10-6w 1n-2

(48")2

c) Th e sum of the lamp irradi a nee pi u s th e reflector i rradi anee is the total iradi ance.

total Es=62 X 10-6 + 319 X 10-6 = 0.38 X 1O-3w in-2

12



EXAM PlE 3: Repeat Example 2 if the reflector fi nish is diffuse.

rb = 1 /2 x 1.4 =0.7w

a) The lamp is very close to the reflector. Consequently one-half of the lamp's radiant power is incident on the reflector.

b) A good diffuse Alzak su rface will have a reflecta nce value close to the specula r value; use 0.6. Since the reflector is sha llow,

neglect the interflections and curvature (these effects oppose and will tend to cancel), and assume it is a Lambert ian surface.

Thus,

M = 0.6 x 0.7w = 0.0058w in-2refl 6" x 12"

L0.0058 8· 2

,.fl =-- = 0.001 w 10- sr"1 1 "

c) The radiant intensity produced by the reflector is

I = Lrofl x Ao,oJ~c'ed = 0.0018 x (6" - 5/8") x 12" = 0.116w sr-1

d) The irradiance at point B dueto the reflector by the inverse square law is

0.116 0 6 • 2E =-- = 50 x 1 - w rnB (48")2

e) The sum of the lamp irradiance plus the reflector irradiance is the total irradiance.

total Ee= 62 X 10-6 + 50 X 10-6 = 0.112 X 1O-3w in-2

EXAMPLE: 4 A relative spectral power distribution curve, R (X), is shown for blue fluorescent lamps. If a particular blue lamp is

rated at 1160l rn, determine the multiplierforthe curve so that it is absolute in watts per micron (WJ.!,-1).

a) Choose a convenient scale for graphical ytork, say the 15 x 20 cm shown. Multiply the relative power curve R O d by the

lumi nou s spectral efficiency function VIA) at each wavelength. Then measu re the area under th is product curve; it turns out

to be 21.0 cm2 on the drawing size suggested.

b) A unit length on the relative power scale is 10 em and a unit length on the wavelength scale is 50 cm. Therefore, a unit areaon the graph scale is lOx 50 = 500 cm2 on the drawing. The area under the product curve on the graph scale is

21.0cm2

=0.042

500cm2

c) If K is the multipler to put the curve in absolute units, then

r b =683 (1mw-'if,[; R (X)) (WJ.!,-I)VIA) dA ( J . ! , ) = 1160 lrn

1.70 =K£R~) V(>")d>..

~I~ , 15

s~ 10

~'".~~~ .s

10

d) The final integral above is the area under the product curve found in part (b). Thus,

K = 1.70 = 40.50.042

,-,I \

I \ V I X I

I V\

\\\

\

\

\

,5 .6

WAvEL[N{i.TH !J r

o 10

"

EXAMPLE 5: Lamps ofthetype described in example 4 produce an illumination of 121m ft-2 ata particular point. What is the

irradiance in the . 3 J . ! , to.4J.!,band at that point?

a) If th e radi ant power is acted on selectively with respect to wavelength, then it is necessary to follow it through the system

applying the proper spectral reflecta nce and spectral transmitta nee fu nctl ons. However, the problem is simple if the radiant

power is acted on non-selectively, i.e., all wavelengths of interest are affected equally. In this example, direct lamp radiation

can be considered in this manner. Also, any reflecting or transmitting material that equally attenuates all wavelengths in the

. 3 J . ! , to . 4 J . ! , region and the visible reg ion of the spectrum could be present.

13



b) The radia nt power between .3/L and . 411-emitted by the lamp is the area under th s absolute spectra I power distri butien

curve between these wavelengths. Measuring this region on our large scale drawing, we find an area of 10.5Cm2. On the

basic graph scale, the area is

10.5 cm2

=0.021

SOOcm2

c) The radiant power is given by

/

.4

4 > .3•.4 '" [ K R ( > " ) ] (WtL-1) d > . . (M )

. 3

/

.4

1 > .J . .4 = = K A U " ' ) d"

.3

d) This final Integral is the area under the curve found in part (b). The value of K is known from example 4.

l / J ,3 . . • ' " 40.5 x 0.021 = = 0.8Sw

e) The ratio of the emitted poweri n the .3/L to .4tL band to the emitted luminous flux is

.85w = = 0.73 x 1O-3w lrn"1160lm

f) Under the stated conditions of non-selected flux control, this ratio is preserved throughout the system. At a point where the

illumination is 121m ft-2, we find

E.J•.4 = = 121m ft-2

x 0.73 X 10-3

w Im-1

= 0.0088wft-2

REFERENCES

1, Huff , C. , Smith, H. , Boring, W, and Clarke, N., "Study of Ultraviolet Disinfection of Water and Factors in Trsatrnant Ef fic iency," Publ ic

Health Reports, U.S. Public Health Service, Vol. 80, p. 695,705, August 1965,

2. Kaufman, J., "Introducing SI Units," Ilium. Engr., Vol. 63, p. 537, October '968.

3. I.E.S. Lighting Handbook, Applications Volume, 6th Edition. p. 19-14 to 19-18. Illuminating Engineering Society, New York 1981,

4. American National Standard: Nornenclatu re and Def in itions for I Ilu minali ng Eng ineering, ANSIIIES RP-16-1980.

5. Koller, L., Ultraviolet Radia,lion, John Wiley and Sons, Inc., New York, 1965 . .

6. levin, R., "Luminance - A Tutorial Paper," Jour. SMPTE, Vol. 77, p. 1005, Oct. 1968.

7, Nicodemus, f. , "Radiornetrv," Applied Optics and Opttcal Engineering, Ch. 8, Vol. 4,editor:R. Ki,ngslake. Academic Press. New York 1967.

8. Nicodemus,F., "Optical Resource Letter on Radiometry, " JOSA, Vol. 59, p. 243, March 1969.9. Sum mer, w . , Ultraviolet and Infrared Eng ineering, Interscience Publishers, Inc., New York 1962.

10. Ult ra-Violet Products, lnc., San Gabriel, California.

11, American Conference of Governmentel and Industrial Hygienists, Threshold Limit Values For Chemical Substances In Work.room Air

Adopted by ACGIH For 1977, ACGI H, Cincin nati 1977.

12, International Light Inc., NeWburyport , Mass.

13. Sliney. D. and Wol,barsht, M., Safety With lasers and Other Optical Sources, Plenum Press, New York 1980.

14. American Ult raviolet Co., Chatham, New Jersev,

ACKNOWLE iDGEMENTS

The author wishes to express his appreciation to the foHow.ing:

Dr. L. J.8uttol ph, Engineer on the staff of the llluml nat ing 'Engi neeri ng Society for his assistance in supplying information on germicidal

lamp applications, including Fig. 4, 6,15-18, and Table m ,Dr. Robert Levin of the General Engineering Dapt., Sylvania Lighting Center, for his assistance in wriiting the section on the calculations in the

ultraviolet spectrum, and providing technical data.

Ultra-Violet Products, Inc. of San Gabriel, California, for Fig. 5A, 58.,11, and 13.

International Light Inc. of Newburyport, Mass. for Fig. 5C.

C. C. MPELKAS

Commercial Engineering Department

14



G30TBG ER M ICID AL L AM PS STARTER REQUIRED

Lamp Std.HoursW atb Bu lb B a s e Ducrlp ilon O rdering Pli.LIfeAbbreviation Qll·

8 T - 5 1 2 " Min . B i~ in Germicidal 0 8 T 5 24 7500G15T8

15 T - 8 1 8 " Med . B ip i n Germicidal & 1 5 T 8 24 7500

3 0 T · 8 3 6 " Med . B ip i n Germicid!l l G 3 0 T 8 2 4 __7500

G8TS

15



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Dearborn, Michigan 48126313-582·8754

Hartford. Connecticut

100 Const itut ion Plaza

Hart ford, Connecticut 06103

203-249-5823

Houston, TeJC8s

1440 Greengrass Drive

Houston. Texas 77008

713·869·8671

Kansas City, Kansas

450 Funston Road

Kansas City. Kansas 66115

913·371·3773

los Angeles, Cal ifornia

6505 East Gayhart Street

PO. Box 2795Los Angeles, California 90051

213-726-1666

Minneapolis, Minnesota (Fridley)

5330 Industrial Blvd., N. E .

Fridley, Minnesota 55421

612·571·9400

New Orleans, Louisiana

5510 Jefferson Highway

New Orleans, Louisiana 70183

504-733·6970

New York, New York

'909 Third Avenue

New York, New York 10022

212-486-3996

SYLVANIA

Orlando, Florida

7492 Chancel lor Drive

PO. Box 13327A

Orlando, Florida 32859

305·859·6220

Philadelphia. Pennsylvania (Devon)

465 Devon Park DriveP.O.Box 500

Devon, Pennsylvania 19333

215·293·9330

Pittsburgh, Pennsylvania

450 Butler Street

P.O.Box 9544

Pit tsburgh, Pennsylvania 15223

412·781-4533

St. Louis, Missouri (Hazelwood)

5656 Campus Parkway

Hazelwood. Missouri 63042

314·731·5515

San Francisco, California (Burl ingame)

1811Adrian Road

Burlingame, Cal ifornia 94010

415·697 ·3500Seattle, Washington

750 So. Michigan Street

Seatt le, Washington 98108

206·763·2660

Teterboro, New Jersey

1000 Huyler Street

Teterboro, New Jersey 07608

201·288·9484

Washington, D.C. (Spr ingf ield, Va)

6610 Electronic Drive

Springfield, Virginia 22151

703·354·3100

Indust,rial/Commercial

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