ANHYDROUSAMMONIA

SAFETY

Copyright 2006 Airgas, Inc.All rights reserved.Quotation or reproduction in whole or in part without written permission is expressly prohibited.

Images on the cover reflect ongoing training using simulated ammonia release events.These mock-release events assist in emergency response training should an accident occur.

ContentsPage

A BASIC UNDERSTANDING .........................................................................................1

GENERAL .........................................................................................................................2

COMMON HAZARDS.....................................................................................................3

OTHER HAZARDS ..........................................................................................................3

CHEMICAL....................................................................................................3

THERMAL EXPANSION..............................................................................3

HUMAN PHYSIOLOGICAL EFFECTS..........................................................................4

EXPOSURE LIMITS .........................................................................................................4

PERSONAL PROTECTIVE EQUIPMENT......................................................................4

EMERGENCY PROTECTIVE AND SAFETY EQUIPMENT........................................4

WATER SHOWER .........................................................................................5

RESPIRATORY DEVICES.............................................................................5

PROTECTIVE CLOTHING ..........................................................................5

RESCUE HARNESS......................................................................................5

WATER SYSTEM ...........................................................................................5

STRETCHER AND BLANKETS...................................................................5

FIRST AID PROCEDURES ..............................................................................................6

INHALATION................................................................................................6

EYES...............................................................................................................6

SKIN AND MUCOSA ...................................................................................6

INTERNAL.....................................................................................................7

EMERGENCY MEASURES .............................................................................................7

LEAK DETECTION..........................................................................................................8

LEAK CONTROL..............................................................................................................9

EQUIPMENT OR PIPING............................................................................9

VALVE ............................................................................................................9

PRESSURE RELIEF DEVICE.......................................................................9

STORAGE TANK...........................................................................................9

SHIPPING CONTAINER..............................................................................9

FIRE EXPOSURE..............................................................................................................10

EMPLOYEE SAFETY TRAINING...................................................................................10

SAFETY REFERENCES AND TRAINING AIDS ..........................................................12

Tables

TABLE 1. VAPOR PRESSURE AND VOLUMEOF LIQUID AT VARIOUS TEMPERATURES.............................................2

TABLE 2. AMMONIA EXPOSURE GUIDELINES .....................................................4TABLE 3. TABLE OF INITIAL ISOLATION AND

PROTECTIVE ACTION DISTANCES .........................................................8

1A Basic Understanding of Anhydrous AmmoniaAmmonia (frequently called anhydrousammonia) is one of the most valuable andversatile chemical compounds in today'smodern world. For example, it finds wideapplication in food production and processing,textile and chemical manufacturing,refrigeration, metal treating and pollutionabatement.

The ever-increasing use of ammonia has beenaccompanied by the need for thedissemination of knowledge regardingammonia safety. Individuals that work withammonia under normal conditions or thosewho may be exposed to ammonia inemergency conditions should have basic safetyawareness training. Recognizing this need,Airgas Specialty Products prepared thisbooklet with a selected collection of helpfulinformation and suggestions for the ammoniauser and for the safety personnel. Thesesuggestions are offered as an aid in thepreparation of a comprehensive safety programand should be altered or augmented inaccordance with individual requirements.Anyone using this publication should researchoriginal and current sources of authority.

Anyone working with ammonia has aresponsibility not only to be thoroughlyfamiliar with basic ammonia safety principles,to observe all necessary precautions, and reactpromptly and appropriately in the event of anemergency. Readers of this booklet will findanswers to questions most often askedregarding general properties, potential hazards,exposure effects, personal protective and safetyequipment, first aid procedures and methodsof dealing with emergencies involvingammonia. Information regarding themanufacture, transportation, and orapplication of ammonia is not detailed.

Persons requiring any information regardingammonia not covered in this booklet are urgedto consult with Airgas Specialty Products(www.airgasspecialtyproducts.com) or with theCompressed Gas Association, Inc., Arlington,Va., or The Fertilizer Institute, Washington,D.C., for assistance. Also refer to29CFR1910.111 and ANSI K61.1 forregulations and additional guidelines forammonia handling and storage.

2Anhydrous Ammonia Safety

GeneralThe term ammonia in this booklet meansanhydrous ammonia which has themolecular formula NH3. Ammonia is formedby the combination of nitrogen and hydrogenat high temperature and pressure in thepresence of a catalyst. Anhydrous meanswithout water. Premium, metallurgical, andrefrigeration grade anhydrous ammoniacontains no more than 33 ppm water, whilecommercial-grade anhydrous ammoniacontains 0.2- 0.5% water. Ammonia(anhydrous ammonia) should not be confusedwith the synonymous terms (ammoniumhydroxide, aqua ammonia or aqueousammonia), which refer to solutions ofammonia in water.

Commercial ammonium hydroxide solutionsgenerally contain 19-30% ammonia in water,while household ammonia typically containsonly 2-4% ammonia in water. These solutionsare commonly known as ammonia, but shouldnever be confused with liquid anhydrousammonia, which has a much greater hazardpotential.

Ammonia is a pungent, colorless gas atambient temperature and pressure and is onlyabout 40% as dense as air. Ammonia gascondenses to a colorless liquid whencompressed and condensed. Liquid ammoniaboils at -28 F (-33 dC) at atmosphericpressure and has a density of 5.69 lb/gal at

that temperature. Liquid ammonia coexistswith ammonia vapor in storage vessels.Temperature affects both the vapor pressureand density of liquid ammonia (see Table 1).The vapor pressure increases and the densitydecreases as the temperature of the liquidrises. It should be noted that the pressureobserved within a storage vessel is NOT anindicator of the quantity of liquid in the vessel.

Liquid ammonia expands when itstemperature increases. Thus, OSHA at29CFR1910.111(b)(11)(i and ii) limits thefilling of ammonia vessels to 87.5% providedthe temperature of the anhydrous ammoniabeing charged is not lower than 30 F.

The filling limit is critical since a vessel filledwith liquid to 87.5% full at 30 F wouldbecome 100% full of liquid if the temperatureof the liquid ammonia reached 124 F. Anyadditional temperature rise above 124 Fwould cause the vessel to bulge and it couldrupture due to the internal hydrostaticpressure caused by the expanding liquid.Ammonia storage vessels must not be exposedto excessive heat because of the expansioncharacteristics. Ammonia storage vessels,except cylinders, are equipped with PressureRelief Valves to prevent excess pressure whichcould lead to catastrophic rupture of thevessels.

Due to these characteristics, ammoniacontainers should not be exposed to excessiveheat. (See THERMAL EXPANSION and FIRE

TABLE 1. VAPOR PRESSURE AND VOLUMES OF LIQUID AMMONIAAT VARIOUS TEMPERATURES

Temperature F Vapor Pressure psig Volume gal/CWT Density lb/gal

-28 0.0 17.57 5.690 15.7 18.10 5.52

30 45.0 18.72 5.3460 92.9 19.43 5.1590 165.9 20.25 4.94

115 251.5 21.04 4.75130 315.6 21.58 4.63

Data derived from U.S. Bureau of Standards Circular No. 142

3EXPOSURE.)

Under equilibrium conditions, the vaporpressure and volume of liquid ammonia varywith temperature as shown in Table 1.

Ammonia is frequently shipped and stored asa liquefied compressed gas under pressure atambient temperature via truck (up to about 20tons) or in 80 ton railcars. It is shipped inDepartment of Transportation (DOT)approved pressure vessels and stored inASME pressure vessels as a liquefiedcompressed gas at ambient temperature. Verylarge quantities (thousands of tons) aretransported in pipe lines as a liquefiedcompressed gas at ambient temperature andhigh pressure. Large quantities are alsoshipped via barge or tanker as a refrigeratedliquid at -28 F and atmospheric pressure.When stored in very large quantities(thousands of tons/vessel) at terminals,ammonia is stored in refrigerated vessels oftenat -28 F and very little pressure.

Common HazardsAmmonia is corrosive to human tissue invarying degrees depending on concentrationand exposure time.

The odor of ammonia is detectable by manypeople at concentrations as low as five ppm inair. Its pungent and distinctive odor atconcentrations of 10-20 ppm range would bevery noticeable by nearly all individuals. Mostpeople would be uncomfortable in ammoniaatmospheres of 30-50 ppm, though ammoniavapor is generally not hazardous atconcentrations below 50 ppm. No reasonablyprudent person would voluntarily remain inhazardous concentrations of ammonia (SeeTable 2).

At the time of this printing, U. S. Departmentof Transportation requires shipping containersto be marked INHALATION HAZARD andthat statement must also be included in theshipping name. Ammonia is classified as aNon-Flammable Gas by the U.S.Department of Transportation. However,ammonia will ignite within the limited rangeof 15-28% ammonia in air by volume at about1200 F. Ignition is not spontaneous and anexternal source of ignition is required.Conditions favorable for ignition are seldom

encountered in normal outdoor storage andhandling. In addition, the heat generated bycombustion of ammonia is not sufficient tosustain combustion, thus ammonia will ceaseto burn when the ignition source is removed.

Other HazardsCHEMICAL - Ammonia is a very stablechemical compound at normal temperatures.It only begins to dissociate into nitrogen andhighly flammable hydrogen at about 840 F.

Ammonia will not corrode most commonmetals. However, in the presence of waterammonia will attack copper, zinc and alloyscontaining copper or zinc. For this reason,materials of construction used for ammoniacontainers, fittings, piping and equipment arelimited to steel and iron or certain non-ferrousalloys resistant to attack by ammonia. See29CFR1910.111(b)(7)(iv) for pipingrequirements on non-refrigerated systems.

Ammonia is a highly reactive chemical, andreacts with inorganic and organic acids toform salts with the release of significant heat.Ammonia is known to react with bromine,chlorine, fluorine, or iodine to formcompounds which explode spontaneously.Also, ammonia has been reported to react withgold, silver or mercury to form fulminate-likecompounds which are explosive.

THERMAL EXPANSION - Liquid ammoniaexhibits a high coefficient of cubic expansion.A given quantity of liquid ammonia expandsconsiderably in volume with a rise intemperature (See Table 1). For this reason,facilities must be installed with hydrostaticrelief valves to prevent hydrostatic rupture ofcontainers, piping and other equipment.

The vapor pressure of ammonia also increaseswith temperature. The vapor pressure is 138psig at 80 F, 271 psig at 120 F and 428 psigat 150 F. Thus, pressure relief valves must beprovided to prevent vessel rupture in the eventof excess pressure due to heat. (Facilitiesmust be installed in accord with29CFR1910.111). Storage tanks must beprotected from external heat sources.

TABLE 2. AMMONIA EXPOSURE GUIDELINES

Effect PPM Ammonia in Air by Volume

Least perceptible odor 5 ppmReadily detectable odor 10-20 ppmOSHA PEL: TWA* 50 ppmIDLH** 300 ppm* Permissible Exposure Limit (PEL): Time weighted average (TWA) concentration that must not be exceeded during any 8hour work shift of a 40 hour workweek.

**Interpretation of NIOSH definition: IDLH is the maximum concentration in which a person can exist for 30 minuteswithout respiratory protection and not sustain acute or permanent health damage or loss of ability to escape. IDLH(Immediately Dangerous to Life or Health) value listed as designated in the NIOSH Pocket Guide to Chemical Hazards(www.cdc.gov/niosh/npg/npg.html, 9/10/04).

4

Human Physiological EffectsAmmonia is NOT a cumulative metabolicpoison; rather ammonium ions are importantconstituents of living systems. The effects ofexposure to ammonia are exposure-time andconcentration dependent. No effects, or onlymild irritation, occur when exposed to lowconcentrations (OSHA PEL = 50 ppm) oreven somewhat higher concentrations forshort periods of time.

Exposure to high concentrations of ammoniacan cause significant health problems and befatal in extreme cases. Exposure tointermediate concentrations of ammonia forlimited periods can cause mild irritation toskin, eyes and respiratory system. Highconcentrations (IDLH = 300 ppm, see Table 2for explanation of IDLH) can causeobstruction of breathing from laryngeal andbronchial spasm, edema and severe damage ofthe mucous membranes of the respiratory tractwith possible fatal results.

Liquid ammonia boils at -28F at atmosphericpressure, acting as a refrigerant to remove heatfrom any warmer object it may be contacting.Accordingly, liquid ammonia in contact withthe skin can cause frostbite and severefreezing.

Ammonia vapor concentrations which aretolerated by some individuals may produceadverse reactions in others. Those havingchronic respiratory disease or have shownevidence of undue sensitivity to ammoniashould not be exposed to ammonia. Table 2

indicates exposure guidelines to variousconcentrations of ammonia in air uponinhalation.

Exposure LimitsOccupational Safety and Healthadministration (OSHA) regulations requirethat an employees permissible exposure limit(PEL) for ammonia is not to exceed a time-weighted average of 50 ppm in an eight-hourworkday 29CFR1910.1000; Table z-1.

Personal Protective EquipmentIndividuals working with ammonia(operations or maintenance) should wearchemical splash-proof goggles plus a full faceshield. The face shield should be worn overthe goggles for additional protection of eyes,respiratory system and face, but never as asubstitute for the goggles. In addition, thoseindividuals should also wear rubber or plasticgauntlet gloves impervious to ammonia toprotect hands and arms. Airgas regards theseitems to be minimal, and additionalprotection, such as rubber aprons or slickers,may be justified to protect critical body areasvulnerable to contact with ammonia.

Emergency Protective andSafety EquipmentEach location having an ammonia installationshould have readily available and freelyaccessible emergency protective and safetyequipment as required by federal, state and

5local governmental regulations as well as goodmanagement practice. The location of suchprotective and safety equipment should beclearly identified by appropriate signs.

Emergency protective and safety equipmentshould include the following:

WATER SHOWER Body parts that havecome in contact with ammonia must beflooded immediately with large quantities ofwater. An emergency safety shower, eye washfountain or other source of clean water can beused for this purpose. Water supplies shouldbe protected from freezing.

RESPIRATORY DEVICES

1. Stationary storage installations must have atleast two suitable gas masks in readilyaccessible locations as per29CFR1910.111(b)(10)(ii). Full face maskswith ammonia canisters that have beenapproved by NIOSH under 42 CFR part 84 arerequired. These approved masks are suitablefor emergency action involving most outdooranhydrous ammonia leaks, as well as someindoor leaks. (See 29CFR1910.13 for detailedRESPIRATORY PROTECTION requirements.)Individuals expected to use gas masks must beclean shaven and trained in the use of gasmasks. Masks with canisters must not be usedin IDLH atmospheres except for escapepurposes.

Any individual wearing a gas mask must leavea contaminated area immediately afterdetecting the odor of ammonia or experiencingbreathing difficulty. These are indications thatthe mask or canister is not functioningproperly, that the ammonia concentration isexcessive, or that adequate oxygen is notavailable.

2. SELF-CONTAINED AIR BREATHINGAPPARATUS (SCBA) of an approved pressuredemand type must be used when enteringareas where ammonia concentrations areunknown, exceed the IDLH level of 300 ppmor are oxygen deficient atmospheres (See29CFR1910.134(d)(2).

The SCBA, which consists of a sealable full-face shield, a pressure and flow control and ahigh pressure cylinder of air, provides

breathing protection for a period of timewhich varies with the amount of air carriedand the extent of exertion by the user. Theuser must have a clean-shaven face and havetraining required by OSHA in the use ofrespirators (See 29CFR1910.134 and29CFR1910.120). The buddy system mustalways be employed when using SCBA(29CFR1910.134(g)(3).

Respiratory devices must be used andmaintained in accordance with themanufacturers instructions. Individualsexpected to use respiratory masks withcanisters or air supply must be well trained tofunction safely in tense emergency situations.

PROTECTIVE CLOTHING Emergency orrescue personnel required to work in highammonia concentrations should wearprotective gloves, boots, pants and jacket (orslicker) impervious to ammonia. A hard hatshould be worn as required by plant practiceor dictated by special hazards. Class A totallyencapsulated suits with SCBA will be requiredin severe ammonia atmospheres that canseverely damage the skin.

RESCUE HARNESS A safety belt andlifeline should be worn by an individual usingrespiratory equipment and enteringcontaminated air in a confined location.Another person also wearing respiratoryequipment and protective clothing should belocated outside the contaminated area to actin case of emergency. See 29 CFR 1910.120and 134.

WATER SYSTEM Ammonia installationsshould have adequate water available for firefighting, and for suppression of ammoniavapor clouds resulting from ammonia leaks.

STRETCHER AND BLANKETS Inadequatefacilities for transporting a seriously injuredperson from the scene of an accident to a firstaid station can add to the seriousness of theinjury. A stretcher provides the mostacceptable method of hand transportation andit may be used as a temporary cot at the firstaid station or during transit in a vehicle.

6First Aid ProceduresAmmonia is one of the most water-soluble ofall gases. Accordingly, the best means ofproviding first aid for an injury caused byammonia contact with the eyes or skin is toflush immediately with large quantities ofpotable water. Promptness in initiatingtreatment, using adequate quantities of waterand continuous application for at least fifteenminutes, or longer if necessary, are all essentialin successful first aid management of an eye orskin injury resulting from contact withammonia. Seek medical attention immediately.

PRIOR TO MEDICAL AID BY THEPHYSICIAN, FIRST AID PROCEDURESSHOULD BE EMPLOYED. THOSEPRESENTED HEREIN ARE BASED UPONWHAT IS BELIEVED TO BE COMMONPRACTICE IN INDUSTRY. THEIRADOPTION IN ANY SPECIFIC CASESHOULD, OF COURSE, BE SUBJECT TOPRIOR ENDORSEMENT BY ACOMPETENT MEDICAL ADVISOR.

As a guide in case of injury caused byammonia, the following first aid proceduresare suggested:

INHALATION Any conscious person whohas incurred irritation due to inhalation ofammonia should proceed at once to a locationfree of ammonia and breathe fresh air. Seekmedical attention if needed.

A person overcome by ammonia must becarried to a location free of ammonia and theservices of a physician obtained promptly.Successful resuscitation requires SPEED andEFFICIENCY. DELAY AND INEXPERIENCEMAY RESULT IN A FATALITY.

If there is an obstruction to the patientsbreathing, the airway must be cleared byappropriate methods which may includeproper positioning of the patient's head,pulling the tongue forward and clearing anyblockage from the mouth such as dentures orvomit. If spontaneous breathing does notresume after the airway has been cleared,artificial respiration should be startedimmediately by mouth-to-mouth resuscitation(expired-air ventilation, rescue breathing),

preferably by an individual trained in theprocedure.

Oxygen therapy may be indicated once thepatient's breathing has been restored or if itcontinues to be labored. Such therapy shouldnot replace immediate mouth-to-mouthresuscitation and should only be appliedduring a sustained resuscitation period or ifthe patient is to be moved. CAUTION: It maynot be advisable to administer oxygen underpositive pressure if the patient is in shock orthere is impending or existing cardiovascularfailure. Oxygen therapy equipment should beused only by qualified and experiencedpersonnel.

Treatment with oxygen may be discontinued ifbreathing becomes easy, the color is good andthere are no signs of lung congestion. Duringtreatment, the patient should be placed in areclining position. He should be kept quiet, atrest and comfortably warm, but not hot. Seekmedical attention.

EYES If ammonia enters the eye, flood theeye immediately with large quantities ofpotable water for at least 15 minutes. Speed isessential. Contact lenses should never beworn in the presence of ammonia, since thelens could trap ammonia in the eye andinterfere with treatment. Water in a squeezebottle which can be carried in the pocket ishelpful for emergency irrigation purposes. Aneye-wash fountain should be used, but if notavailable, water from any source may bepoured into the eyes. In any case, the eyelidsMUST BE HELD OPEN and irrigationcontinued for at least 15 minutes. Continueirrigation with 10 minute breaks and 5minutes irrigation until Medical attention isobtained. MEDICAL ATTENTION must bereceived immediately, preferable from anophthalmologist. Medication, of any type,should not be placed in the eyes unlessordered by a physician.

SKIN AND MUCOSA If contacted by liquidammonia or high concentrations of ammoniavapor, immediately flood the affected bodyparts with water. If a safety shower is notavailable, use any available water supply.Water will thaw any clothing that may be

7frozen to the skin. After thawing, removecontaminated clothing and continue floodingthe contaminated skin with water for at least15 minutes to remove ammonia from the skin.SEEK MEDICAL ATTENTION IMMEDIATELY.Do not apply medication to the burned areaswithout medical advice.

INTERNAL Swallowing of liquid ammoniais very unlikely. However, if ammonia hasbeen taken internally and if the patient isCONSCIOUS and able, have him drink largequantities of water immediately. NEVER GIVEANYTHING BY MOUTH TO ANUNCONSCIOUS PERSON. Should thepatient vomit, place his face down with headlower than hips to prevent it from entering thelungs. Transport patient to a physicianpromptly and apply other first aid treatment asthe doctor may prescribe.

Emergency MeasuresEvery facility is susceptible to emergencysituations which can result in property damageand/or bodily harm to employees, visitors orneighbors. A facility using ammonia bearsresponsibility for the development andimplementation of effective Emergency Action(or response) plans as per 29CFR1910.38 to beprepared to deal with emergency situations.Facilities that have 10,000 pounds or more ofanhydrous ammonia must also developProcess Safety Management (PSM) programsas per 29CFR1910.119 and Risk ManagementPrograms (RMP) as per 40CFR68. EffectiveEmergency Action Plans, PSM and RMPprograms help facilities avoid and be preparedfor emergencies as well as comply with Federalregulatory requirements.

No one plan will serve the needs of allcompanies. Each organization must assess thevarious potential emergency conditions thatmight occur and develop a program to suit itsown requirements. Where ammonia is storedand used, the following procedures andactions are suggested for incorporation into anemergency action or response plan upon theunderstanding that the publisher is notoffering professional advice.

When an ammonia leak occurs, personneltrained for and authorized to handle such

situations should take immediate steps tolocate and control the condition. Respiratoryequipment and protective clothing suitable forammonia must be worn. All other personsmust be kept away from the affected area untilthe leak has been stopped. Remain upwind ofthe leak when possible.

If ammonia vapor is released, the irritatingeffect of the vapor will generally forcepersonnel to leave the area before they areovercome by harmful concentrations.Sufficient, well-marked and readily accessibleexits must be provided to facilitate rapidevacuation from a building. Should anindividual become trapped in an ammonia-contaminated atmosphere, breathing should beheld to a minimum and eyes opened only asnecessary.

Since ammonia vapor is lighter than air, atrapped person should remain close to thefloor to take advantage of lower vaporconcentrations while seeking an escape route,unless liquid ammonia has been spilled. Ifrespiratory equipment is not available, sometemporary protection may be afforded byholding a wet cloth over the nose and mouth.

Significant ammonia releases MUST bereported to authorities immediately. Releasesof 100 pounds or more of ammonia in anycontinuous 24-hours period must be reportedto the Local Emergency Planning Commission(LEPC), Fire Department, State EmergencyResponse Commission (SERC) and NationalResponse Center (NRC; phone 800-424-8802)immediately as per 40CFR355.40. Smallerreleases that may have an offsite impactshould be reported to the LEPC and FireDepartment, and possibly the SERC.

Evacuation of the surrounding area may berequired in the case of significant ammoniareleases. Suggested evacuation distances aregiven in Table 3, starting with the circle asshown in the accompanying diagram.

With good ventilation or rapidly moving aircurrents, ammonia vapor, can be expected todissipate readily to the upper atmosphere.Further action may not be required other thanto stop the leak. If necessary, theconcentration of ammonia vapor in the air canbe reduced effectively by the use of an

8adequate volume of water applied through aspray or fog nozzle.

Under some conditions, ammonia in acontainer may be colder than available watersupply. At such times, water must not beapplied to the container walls since heatwould be transferred to the ammonia thuscausing increased pressure within thecontainer resulting in increased leakage orrelief valve discharge.

Water should not be applied to a liquid spillunless at least 100 parts of water to 1 part ofammonia are available. Runoff of a liquid spillshould be diverted if the direction of flow willcreate an additional problem. UNDER NOCIRCUMSTANCES SHOULD AN ATTEMPTBE MADE TO NEUTRALIZE ANAMMONIA SPILL WITH AN ACID.

An up-to-date telephone listing of variousemergency, rescue, medical and regulatoryagencies should be maintained for use bydesignated personnel. The list should includenumbers for fire and police departments,ambulance, rescue or paramedical services,doctors, hospitals, governmental authorities,material and equipment suppliers. The namesand numbers for selected company supervisoryand management personnel who are to benotified of an emergency situation should be

included. Where appropriate, both day andnight or alternate numbers should be shown.

If company or security personnel are notpresent at a facility during off-hours, thename(s) and telephone number(s) of aresponsible individual(s) should be posted at agate or entrance for purposes of notificationby local authorities should an emergency arise.

Leak DetectionAn ammonia leak is readily detectable by itscharacteristically pungent odor. The locationof a small leak may often be determined byholding a moist strip of phenolphthalein orred litmus paper near the suspected leaksource. The rapidity and intensity of the colorchange in the paper will give some indicationof leak proximity or size. In the presence ofammonia, phenolphthalein paper will turnfrom white to pink or deep red, whereas thered litmus will become blue.

Sulfur dioxide vapor reacts with ammonia toform a dense white cloud and may be used forleak detection. Care must be exercised toavoid breathing sulfur dioxide vapor as it isalso highly irritating. It should be noted that agas mask canister which is specific forammonia will not offer protection againstsulfur dioxide. If there is an appreciable

TABLE 3. TABLE OF INITIAL ISOLATION AND PROTECTIVE ACTION DISTANCES

Small Spill Large Spill

A) Downwind and Crosswind Distances: 0.1mi. Day A) Downwind and Crosswind Distance: 0.2mi. DayDownwind and Crosswind Distances: 0.2mi. Night Downwind and Crosswind Distance: 0.5mi. Night

B) Isolation Zone Diameter: 100 ft.

(Derived from 1996 North American Emergency Response Guidebook,

U.S. Department of Transportation NAERG 96)

B

Initial ProtectiveAction Zone(No Fire)WIND

A

A

9quantity of ammonia in the air, it may bedifficult to pinpoint the leak source. Varioustypes of devices are available to detect andmeasure the concentration of ammonia vaporin air. One such device, known as a Draegertube, employs a colorimetric detector tubethrough which air to be tested is drawn by aspecial hand or battery operated pump. Acomparison of the length of the color stainproduced in the tube is made with a calibratedchart which gives an indication of theconcentration. The use of electronic leakdetection systems may be useful at facilitiesthat are not staffed at all times.

Leak ControlEQUIPMENT OR PIPING If a leak occursin equipment or piping, shut off the ammoniasupply and carefully vent all ammonia fromthe system before attempting to dismantle anypart or make repairs. The appearance of froston an external surface indicates the presenceof liquid ammonia vaporizing in the system.Accordingly, the frost should be allowed todissipate before breaking any connection. Ifwelding is required, the system should bethoroughly purged until all ammonia and anyoil residue has been removed. Cutting orwelding must conform with applicable codes.

VALVE A leak at a valve stem can usually bestopped by tightening the packing gland nut. Aleak at a valve bonnet may be stopped bytightening the bonnet threads or the boltsholding the bonnet to the valve body. Alltightening should be performed slowly andwithout application of excessive force. Packinggland nut and bonnet threads on someammonia valves are left-handed. If tighteningprocedures fail to stop the leak, the valveshould be closed. If the valve should fail toclose completely, it should be plugged.

PRESSURE RELIEF DEVICE A leak ordischarge through a pressure relief device,such as a pressure relief valve, may occur if thepressure within the equipment, piping, tank orcontainer exceeds the rated pressure setting ofthe device or if the device is faulty. Reducingthe pressure within the system by removingammonia as vapor to process or cooling thecontainer with a water spray may permit the

device to reseat. If reseating does not takeplace, it may be necessary to replace thedevice with one approved for ammonia serviceand of the proper pressure rating and capacity.

No attempt should be made to plug, cap orotherwise tamper with a pressure relief deviceunder any circumstances (See 29 CFR1910.111 (b)(9)(iii)). However, a pressure reliefvalve may be provided with a shut-off valve.This will allow the leaking device to beisolated for removal purposes while anotherpressure relief valve provides the full rate ofdischarge capacity required for safety. Unlessreturned to the manufacturer, a pressure reliefdevice should not be repaired or adjusted inany manner. Pressure relief valves should bereplaced at regular intervals as suggested bythe manufacturer. Failure to observe theseprecautions could result in a seriousweakening or catastrophic rupture of theequipment, piping, tank or container whichwas being protected by the device.

STORAGE TANK A leak at a threaded orflanged storage tank opening may often bestopped by a careful tightening of threads orbolts. Should such efforts fail, it will benecessary to empty the tank of all ammoniabefore attempting further repair. If the leak issmall, the tank can frequently be emptied byremoving the ammonia as a vapor or liquid toprocess. If it is necessary to remove theammonia, or if the tank is equipped with avaporizer, Airgas should be contacted foradvice and assistance at 800-295-2225.

Occasionally, a storage tank will develop aleak in a plate, weld or coupling. No attemptto repair such a leak should be made. Instead,call your tank or ammonia supplier promptly.Welding on an ammonia storage tank must beperformed in accordance with ASME codeprocedures and only after complete purging.

SHIPPING CONTAINER Ammonia isshipped in special containers which arefabricated, transported and maintained inaccordance with the U.S. Department ofTransportation regulations. Shippingcontainers include cylinders, portable tanks,tank trucks, rail tank cars, barges and tankers.If an ammonia leak occurs in a shippingcontainer while at the users facility, these

10

actions should be taken to limit and controlthe escape of ammonia:

(1) If liquid is leaking from a cylinder, positionit so that vapor escapes instead of liquid.The rate of ammonia release from a vaporleak is considerably less than from a liquidleak through an opening of the same size.

(2) If possible, move the container to an areaof reduced hazard.

(3) If no risk is entailed, attempt to reduce thepressure in the container by removing theammonia to process as a vapor.

(4) Reduce the quantity of vapor in theatmosphere with a water spray applied tothe leak area.

(5) Aside from trying to stop a leak from ashipping container by tightening a valvepacking nut, closing a valve or possiblytightening a flange bolt, no other repairsshould be attempted or authorized by theuser.

(6) It is a violation of federal regulations totransport an ammonia shipping containerwhich is leaking or damaged. If a shippingcontainer is damaged or is leaking in amanner which cannot be handled bypersonnel at the site, the nearest office ofthe producer or supplier should be calledfor assistance. If the producer or suppliercannot be reached, contact the ChemicalTransportation Emergency Center(CHEMTREC) by telephoning the toll freenumber (800) 424-9300 for advice or helpday or night.

When calling for assistance, be prepared toprovide the following information:

(a) Nature of emergency: when, where andextent.

(b)Type and condition of container.

(c) Name of shipper or supplier.

(d)Extent of injuries or property damage,if any.

(e) Description of surrounding area andprevailing weather conditions.

(f) Corrective measures being applied.

(g) Name of caller and location now andwhere telephone contact may be re-established with caller or otherresponsible party at the emergency site.

Regulations require immediate (within 15minutes) reporting of ammonia releases over100 lbs. to the following agencies: FireDepartment, LEPC, SERC, and NRC (800-424-8802).

Fire ExposureIf possible, an ammonia container should bedisconnected and removed immediately fromthe fire zone. If, for any reason, a containercannot be moved, it should be kept cool withwater until well after the fire is extinguished.Firefighting personnel should be properlyequipped with protective clothing andrespiratory equipment.

Employee Safety TrainingSafety in working with ammonia depends onmore than just the availability of personal oremergency protective equipment and clothing.Employee training in safe operationprocedures, in first-aid measures and in theuse of suitable operating and protectiveequipment, properly maintained, must also beincluded as an essential element in anycomprehensive safety program.

Such safety training is the responsibility ofmanagement and should be given to new andold employees at periodic intervals as neededto maintain high proficiency levels. Writtenand oral instructions should be providedfollowed by drills regarding the location,purpose and use of personal and emergencyprotective clothing, equipment, safety showersor other water sources, first aid supplies andshut-down equipment such as valves andswitches.

Training should also stress the avoidance ofbody contact with liquid ammonia orinhalation of gas and the reporting ofequipment failures to appropriate supervisoryauthority.

The information and suggestions compiled in this booklet are derived from sources believed to be reputable andreliable. HOWEVER, AIRGAS INC. SUPPLIES THIS BOOKLET MERELY AS A GRATUITOUS SERVICE ANDMAKES NO WARRANTY OR GUARANTEE OF RESULTS, OR OF ANY OTHER MATTER WHATSOEVER,EXPRESSED OR IMPLIED, AND ASSUMES NO LIABILITY WHATSOEVER IN CONNECTION WITH THEINFORMATION AND SUGGESTIONS HEREIN. No assumption shall be made as to the correctness orsufficiency of any representation in the booklet or that certain circumstances may not warrant or require modifiedor additional precautions or actions.

This booklet is not intended to present applicable federal, state or municipal laws, rules or regulations, insurancerequirements or national safety codes, although some statements may be similar or identical. The reader isinstructed to obtain competent professional advice regarding compliance with applicable laws.

11

Additional copies of this booklet are availableby forwarding a request to Airgas Inc. at (770)717-2200 or info@airgasspecialtyproducts.com.

Material Safety Data Sheets are available bysimilar request.

Selected Ammonia Safety References and Training Aids

1. Safety Requirements for the Storage andHandling of Anhydrous Ammonia, ANSI-K61.1American National Standards Institute, Inc. (ANSI)1430 BroadwayNew York, NY 10018(212) 354-3300

2. Anhydrous Ammonia, Pamphlet G-2Compressed Gas Association, Inc. (CGA)1235 Jefferson Davis HighwayArlington, VA 22202(703) 979-0900

3. Anhydrous Ammonia Safety VideoAirgas Inc.6340 Sugarloaf ParkwayDuluth, GA 30097(770) 717-2200www.airgas.com

4. For The Rest of Your Life, 16mm color sound filmNational Society for the Preservation of Blindness, Inc.79 Madison AvenueNew York, NY 10016(212) 684-3222

REGULATORY REFERENCESCFR = Code of Federal Regulations

29CFR can be found at "http://www.osha.gov"

29CFR1910.111 Storage and Handling of Anhydrous Ammonia

29CFR1910.119 Process Safety Management of Highly Hazardous Materials

29CFR1910.134 Respiratory Protection

40CFR can be found at "http://www.epa.gov" under Laws, Regulations &Dockets

40CFR68 Chemical Accident Prevention Provisions (Risk Management PlanRequirements)

12

6340 Sugarloaf ParkwayDuluth, GA 30097

(770) 717-2200www.airgas.com

MCM-109Rev 6/06