BY CARL MEYER
When called to a fire in-volving a liquefied petroleum gas (LPG) barbecue grill, you generally will encounter one of three types of fires: a grease fire in the body of the barbecue, a fire that involves the hose that connects the barbecue to the regulator (the regulator remains intact and is still controlling the flow of LPG), or a fire that burns directly from the cylinder valve.
Although the first two types of fires may develop into something worse, they are generally easy to control. The third type must be appropriately dealt with in a timely manner to prevent a boiling-liquid, expanding-vapor explosion (BLEVE). A BLEVE occurs when flame impingement weakens the cylinder. The heat causes the cylinder’s internal pressure to increase and the cylinder to eventually fail at the weakened point.
LPG is composed of several hydrocarbon gases. The primary ingredient, propane, is an ambient substance with a vapor density of 1.6. It is colorless and odorless and has a boiling point of -44°F. Propane is odorized so that a leak can be detected. The expansion ratio is 270:1. Each cubic foot of liquid becomes 270 cubic feet of gas. The flammable range is 2 to 10 percent.
The Grease Fire
The grease fire that occurs within the barbecue is fairly simple to handle. It occurs when built-up grease inside of the barbecue ignites. If the alarm is received early and there isn’t an exposure problem, simply stop the flow of gas and extinguish the fire with a dry chemical extinguisher (it is a class B fire). Sometimes, just closing the lid of the barbecue and shutting off the gas will be sufficient. If there is an exposure problem, stretch the appropriate handlines, and secure a water source. At this point, you may have a structure fire to contend with, and you should proceed accordingly.
The LPG cylinder still must be shut off and moved away from the structure.
Fire in Hose That Connects Unit to Regulator
The absence of a grease cup below the body of the barbecue can cause a fire that involves the hose that connects the barbecue to the regulator. (The regulator remains intact and is still controlling the flow of LPG.) Hot grease drips onto the hose. After a while, the fire burns through the hose, causing a leak that may ignite.
On your arrival, a slow-burning flame will be visible from the burned-through hose. The amount of LPG escaping from the hose is regulated, since the regulator remains intact. Turn off the cylinder valve with a gloved hand. The flow of gas will stop, and the fire should go out. The hose will probably continue to burn. Treat this as a class A fire, and extinguish accordingly. A water can will do the trick.
 (1) A grease fire in the body of a barbecue. (Photo by author.) |
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 (2) Product burning from a burned-through hose. (Photo by author/courtesy of the Nassau County Fire Service Academy.) |
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Fire from the Cylinder Valve
If you respond to a propane barbecue fire and hear a loud sound similar to that of a jet engine on arrival, get ready for action. Secure a water source, and stretch at least two 13/4-inch lines. All members should be wearing full personal protective equipment and SCBA. Such a fire may occur for several reasons; the most common one is that the cylinder valve connection is loose or cross-threaded. If left to burn, the other two types of fires involving barbecues may develop into this type of fire. The priority here is to cool the cylinder’s vapor space to prevent a BLEVE. Nozzle teams should take cover while applying cooling water to the vapor space. DON’T STAND OUT IN THE OPEN! If a BLEVE should occur, you will want to be protected from the concussion and the ensuing fireball and shrapnel. The corner of a house or garage or a substantial shed will provide sufficient protection. A lounge chair or an overturned picnic bench will not give adequate protection. Get behind something substantial, and flow water on the cylinder for several minutes before approaching the cylinder to stop the gas flow. In most situations, the valve handle will have melted away. A pair of vise grips may be used to shut the valve; however, in most cases it is easier and safer to allow the LPG to burn off while cooling the cylinder. LPG cylinder fires are true emergencies and should be treated as such.
 (3) Fire burning directly from the cylinder valve. |
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 (4) Fire burning from the cylinder and relief valves. (Photos by author/courtesy of the Nassau County Fire Service Academy.) |
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SOME GUIDELINES
Following are some guidelines for mitigating a fire involving LPG.
- When impingement on the vapor space has occurred, cool the cylinder with water for several minutes before approaching.
- Do not extinguish an LPG fire while cooling the cylinder. If you do, vapor will be escaping the cylinder with an expansion ratio of 270:1.
- Don’t overturn a burning cylinder with the hose stream. An overturned cylinder will allow liquefied product to escape and burn, and the hose stream may propel the burning cylinder into a more precarious location, such as under a deck. Ordinarily, the cylinder would still be attached to the barbecue frame, making it difficult to overturn the cylinder, but it may still be a possibility.
- Use a 30° fog pattern. Do your best to just cool the vapor space.
- Always operate in a position perpendicular to the cylinder and relief valves. When the pressure within the cylinder becomes too great, the relief valve will operate and discharge a highly pressurized flame.
- Remember that LPG vapors are heavier than air (vapor density is greater than 1.0), and seek out low-lying areas such as basements. Whenever you encounter an LPG leak, inspect nearby basements with meters. If you find LPG vapors, remove the sources of ignition, and ventilate.
- When in doubt, secure a water source, and stretch handlines. If you err, err on the safe side.
- When you apply water, take care not to cause any unnecessary water damage whenever practical. The simple act of closing basement windows can go a long way in the public relations department.
- When you use proper tactics, BLEVEs seldom occur. Exposures are almost always a problem.
- Don’t get tunnel vision. Be aware of the entire situation before you. For example, at a recent house fire to which the Seaford (NY) Fire Department responded, we experienced a BLEVE involving a beer keg. The keg was on the rear deck that was fully involved (along with the majority of the house). On the deck was also a 20-pound barbecue LPG cylinder. The keg exploded soon after our arrival. Half of the keg remained in the charred wreckage that was the deck; the other half was propelled through the air about 100 feet and bounced off a neighbor’s roof before it came to rest in a backyard. Fortunately, no one was injured. Members stretched a line to the rear yard and cooled the LPG cylinder for several minutes before moving it away from the house.
CARL MEYER is a 22-year veteran and former chief of the Seaford (NY) Fire Department and second deputy chief instructor at the Nassau County Fire Service Academy.
