CHAPTER

IIIRECOGNIZING AND AVOIDING THE HAZARDS OF PROPANERECOGNIZING AND AVOIDING THE HAZARDS OF PROPANE

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INTRODUCTIONFatalities to first responders have involvedpropane. The purpose of this program is to:

� help you to understand the properties ofpropane,

� give you a basic knowledge of how thepropane system works,

� make you aware of the hazards of propane, and

� offer approaches for responding to propaneemergencies.

This chapter will help you better understand anddetermine what precautions need to be takenwhen responding to propane incidents. Propanecan be dangerous and can injure and/or kill emer-gency workers. For specific facility and specialemergency response needs in your service area,meeting with your local propane provider or thepropane association on a periodic basis is stronglyrecommended.

PROPERTIES ANDCHARACTERISTICS OF PROPANE

This section provides a general summary of the prop-erties of propane. Key safety and tactical points areindicated.

Propane is a liquefied petroleum gas found trappedin pockets with either crude oil or natural gas. About30 percent produced today is refined from crude oil,with the other 70 percent processed from natural gas.Propane is odorless, tasteless, and colorless in its nat-

ural state; an odorant (ethyl mercaptan) is added,similar to natural gas, so that leaks may be detected.

Propane belongs to a family of chemical com-pounds known as hydrocarbons. This means they aremade up of hydrogen and carbon atoms only. Naturalgas (methane) has one carbon atom and four hydro-gen atoms; propane has three carbon atoms witheight hydrogen atoms. This chemical compositionmakes propane similar to natural gas in many char-acteristics.

At a temperature colder than -44°F and open to theatmosphere, propane will reside in its liquid state. Itwould appear to be water. Propane due to its chemi-cal characteristics is portable energy as we can storeit as a liquid in a container under moderate pressureand then use it as a gas when withdrawn from thecontainer. Each unit of liquid propane in a containerproduces 270 units of propane vapor.

The ignition temperature of propane in air is920°F. The heating value of propane is about 2,500Btu/cf, with its flammability range in air 2.15 to 9.60percent. As for natural gas, propane is non-toxic.However, it presents a possible inhalation hazard ifreleased in a confined space, as it displaces oxygenand acts as a simple asphyxiate. Liquid propane is aneffective refrigerant. It rapidly absorbs heat from theskin and can cause severe burns to the body.

Firefighter Fact Propane in its liquid state isabout half the weight of water, while in its vaporstate it is heavier than air and natural gas. Thus,when present, propane tends to go down andlay in low areas, while natural gas, being lighterthan air, tends to travel upward.

Natural Gas SG = .6Air SG � 1.0Propane SG � 1.5

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PROPANE DELIVERYSYSTEM

This section provides an overview of the propane de-livery system. Key safety and tactical points are iden-tified. For specific facility and special emergencyresponse needs in your service area, meeting withyour local propane provider or the propane associa-tion on a periodic basis is strongly recommended.

Propane is shipped from the refinery or natural gasprocessing plant to a local terminal and from there tothe end user. Shipment to the local terminal can bevia truck, railcar, or pipeline. All propane is shippedunder pressure in its liquid state. From the local ter-minal (“bulk plant”) to the residence or commercialproperty, delivery is effected by a bulk delivery truck,called a “bobtail.” This truck would hold about 2,000to 3,500 gallons of propane.

The “bobtail” truck transfers propane via truckhose to the consumer’s storage container. This con-tainer could either be a United States Department ofTransportation (“DOT”) cylinder, or an ASME stor-age tank. The design pressure of the American Soci-ety of Mechanical Engineers (“ASME”) storage tankis 250 psig, while that of the DOT house cylinderwould normally be 240 psig. Either type of containerwould have a filler valve, pressure relief valve, ser-vice valve, and liquid level gauge located within thecylinder neck-ring or the tank dome. Some of the in-dividual process features can be combined in onevalve on the container. All process connections areprotected either by an excess flow valve or a checkvalve in the event of a downstream piping breakage.The DOT cylinders would normally be placed adja-cent to the residence or commercial building with apressure regulator installed within the cylinder neck-ring (collar) along with the cylinder valve. The cylin-der propane capacities would normally be 47 gallons(200 lbs) or 100 gallons (420 lbs). Two or more cylin-ders could be manifolded together. Entry to the build-ing would be via aboveground copper tubing or steelpiping from the cylinder with a shutoff valve in thegas service line. A gas meter or second stage regula-tor would be optional.

The ASME storage tanks could be installed above-ground or underground. The tanks would normally bea 500 gallon or 1,000 gallon (w.c) size. Propane isfilled in a container to about 85 percent of its watercapacity (i.e., a 1,000 gallon water capacity storagetank would be filled to a maximum propane volumeof 850 gallons). The ASME container would be in-stalled 10′ or further away from the building, with ba-sically the same piping characteristics as the DOTcylinder installation, except that the piping run to the

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building from the ASME tank would normally beunderground. It is important to note that all propanecontainers are never completely filled. The approxi-mate 15 percent of the gross capacity (w.c.) of thecontainer is used as a space for propane vapor. Thisallows for expansion of the propane liquid withinthe container. The propane pressure within thecontainer is dependent on the outside ambient tem-perature. At 20°F the propane container pressurewould be 40 psig; at 100°F, the pressure would be172 psig.

Large multiple stationary ASME propane storagetanks ranging in size from 30,000 to 60,000 gallons(w.c.) are employed at various industrial plants andgas utility plants where propane is employed as asupplemental fuel to natural gas.

KEEPING THE SYSTEM SAFE

This section provides a reference of the regulationsapplicable to the propane distribution system in NewJersey.

Responsibility for system maintenance would bethat of the user and the propane supplier. The gov-erning regulation in New Jersey, established by theLiquefied Petroleum Gas Act (N.J.S.A. 21:1B-1 etseq.), for propane systems is N.J.A.C. 5:18 admin-istered by the New Jersey Department of Commu-nity Affairs (“NJDCA”). The State has adoptedNFPA pamphlet #58, the LP-Gas Code, as part ofthe state regulation. The propane supplier at thetime of residential/commercial delivery is to inspectthe container and outside system for acceptabilityand continued usage, Figure III-1.

GENERAL EMERGENCYRESPONSEPROCEDURES

This section provides approaches for responding topropane incidents.

Upon arrival at the scene, a security perimetershould be established. Special care should be used toposition emergency vehicles so that equipment isparked well outside the area of greatest risk. Controlignition sources immediately. If possible, rescueshould be performed from an upstream location.

Large releases of propane may travel great dis-tances, find ignition sources, and flash back to the

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source of the leak. During approach to the incidentscene, avoid committing or positioning personneland vehicles in a hazardous position or situation.Remember—unignited propane is heavier than air.

For escaping gas, hose streams with fog nozzlesare to be used to disperse the propane gas away fromany possible sources of ignition. Approach the leakfrom upwind and keep out of any vapor cloud. Acombustible gas detector should be used to determineif hoselines are effective in dispersing the propane

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gas. When the gas indicator is considered within asafe range (below 10 percent of the Lower Flamma-ble Limit—LFL) rescue and repairs to shut off theflow of gas can be made by the fire service and thepropane gas supplier.

For burning gas, approach the fire from upwind,making sure that one stays out of the range of anypossible flashback. The top of the container (vaporspace) supplying the fuel should first be cooled withhose streams (water should also be applied to the

Figure III-1 Various propane facilities.

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balance of the container). Cooling the container willcause the pressure to be reduced, thus closing any re-lieving container relief valve that might be feedingthe fire. Do not extinguish the fire until the propanefuel supply can be shut off. If a container servicevalve is controlling the fuel feeding the fire, the sur-rounding atmosphere should be cooled with converg-ing fog streams while the fire service attempts toclose the valve. Continue to cool the container wellafter the fire has been extinguished. The area aroundthe container should be monitored for flammable gasusing a combustible gas indicator.

If the source of the fuel cannot be shut off, let thefire burn. Continue to cool the propane containersand adjacent exposures, Figure III-2.

A propane tank contains liquid and vapor. Any ex-ternal fire creating direct flame impingement on thevapor space will heat the tank’s shell. If a vessel getsintense, concentrated heat on the shell area on top (va-por space) of the vessel, the metal will get hot andstart losing its tensile strength. The vessel will start toswell in the hot area. This is an indication that the highpressure will soon blow out as the hot steel is beingdrawn thinner. When the blister rips, the whole tankcontents will erupt upwards, causing a brief tower offire. BLEVE is an acronym for Boiling Liquid Ex-

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panding Vapor Explosion. A BLEVE is defined as acontainer failure with a release of energy, often rap-idly and violently, which is accompanied by a release ofgas to the atmosphere and propulsion of the container orcontainer pieces due to an overpressure rupture.

PROPANE CARGOTRUCK EMERGENCYRESPONSE

This section provides approaches for responding topropane cargo truck incidents.

A propane truck is involved in a traffic accident anda gas cloud is escaping from the vehicle. After secur-ing the site, the objective for this operation is to con-trol or stop the propane from escaping the truck.Firefighters in full protective clothing should deployhoselines to disperse and dilute the flammable gaswhile an approach is made to ascertain exactly wherethe leak is. A combustible gas detector should be usedto determine the effectiveness of the hoselines in dis-persing the gas. If there is severe damage to the truck’spiping, the truck may have to be unloaded. Consider-able time may pass until a compatible vehicle is avail-able on scene for product transfer. Some attempt tostop the leak via a fiberglass wrap or a freeze wrap maybe attempted by the fire service employing a water fogenvelope. As there is no fire situation, if the ambienttemperature is about 90°F, hose water fog played onthe top of the tank can be effective in keeping thetank’s shell cool. If the ambient temperature is below40°F, hose water application should not be applied asit would only raise the temperature of the propane in-side the vessel and thereby increase the tank pressureand the leak. Water should be available in case of firedevelopment and the need to cool the vessel shell.

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Figure III-2 Propane placard. Figure III-3 Propane tank.

Caution Any decision to approach a propanetank showing direct flame impingement on itsvapor space must be made on a case-by-casebasis after evaluating the hazards and risks anddetermining if an adequate supply of water isavailable to support firefighting operations. Bulkstorage tanks can fail within 10 to 20 minutes ofdirect flame impingement if the containers arenot adequately cooled, Figure III-3.

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PROPANE VEHICLEEMERGENCY RESPONSE

This section provides approaches for responding topropane vehicle incidents.

Propane motor fuel tanks may be installed in cars,vans, pick-up trucks, and buses. Propane motor fueltanks are manufactured in a variety of sizes andshapes to accommodate different vehicle designs.Fuel tank capacities normally range from 20 to 65 gal-lons. For automobiles the tank is mounted in thetrunk. The motor fuel tanks are DOT cylinders with adesign pressure of 312 psig. The container relief valveis vented to the outside with the relief valve dischargedirected up or down within 45 degrees of vertical. Anautomatic fuel shutoff valve located as close as possi-ble to the carburetor is provided to close propane flowwhen the engine is not running, though the ignitionswitch may be in the on position. Each vehicle pow-ered by propane is identified with a diamond-shapedlabel located on the lower right rear of the vehicle (theword propane is centered in the diamond in silver orwhite reflective material on a black background).

In the event of a vehicle accident and fire, the re-sponders should cool the propane motor fuel tank onthe vehicle. If there is a propane fire in the enginecompartment, this can be controlled by shutting offthe engine, which should automatically close thepropane fuel supply valve. Rescue of people from theburning vehicle must be evaluated/rendered whilethe fire is attacked and extinguished. While thepropane storage tank is continuously being cooled,the responders should locate the fuel supply valve onthe storage tank and close it. Continue to cool thecylinder until well after the fire has been extin-guished. The cylinder metal surface should be cool

RECOGNIZING AND AVOIDING THE HAZARDS OF PROPANE ■ 89

enough to touch. The area around the containershould be monitored for flammable vapors using acombustible gas indicator.

BARBECUE GRILLFIRE/LEAK RESPONSE

This section provides approaches for responding topropane grill incidents.

Most barbecue gas grills are fitted with a 20-lbDOT propane cylinder. In the event of leakingpropane gas, hose streams with fog nozzles are to beused to disperse the gas away from any possiblesources of ignition. Approach the leak from upwindand keep out of any vapor cloud. A combustible gasdetector should be used to determine the effective-ness in dispersing propane gas with the hose streams.When the gas indicator is considered within a saferange (below 10 percent of the LFL) the fire serviceshould attempt to close the propane cylinder valve(note that this cylinder valve is right-to-tight), thusshutting off the flow of gas.

In the event of fire, the first objective is to cool theoutside of the cylinder so that the cylinder pressure isreduced and the cylinder relief valve resets. Adjacentexposures should also be protected. The respondersshould then approach, from opposite the relief valvedischarge, the cylinder under the protection of handlines so as to manually close the cylinder valve (notethat this cylinder valve is right-to-tight). Continue tocool the cylinder until well after the fire has been ex-tinguished. The cylinder metal surface should be coolenough to touch. The area around the grill should bemonitored for flammable vapors using a combustiblegas indicator.

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REVIEW QUESTIONS1. What are the properties of propane and propane

leaks that a first responder must consider whenresponding to a propane incident?

2. Describe your response to a propane fire?3. What is a BLEVE?

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