BY CARL MEYER
A liquefied petroleum gas (LPG)-fueled barbecue is pretty much standard issue to just about every household these days. A multitude of problems involving the LPG barbecue can occur that may necessitate the response of the local fire department. The different types of fires that may occur were discussed in my previous article (see “LPG Barbecue Fires,” Fire Engineering, October 2003). Discussed here are the types of leaks involving the LPG barbecue that may be encountered. Most of these leaks don’t always present a severe hazard, but they do need to be corrected.
LPG is a flammable gas that is heavier than air. The combination of these two physical properties along with a liquid-to-vapor expansion ratio of 270:1 can present a problem. It is a flammable gas that collects in low-lying areas such as basements, under decks, and in drainage culverts and must be dealt with in a timely manner. Sources of ignition must be removed, and positive-pressure ventilation (PPV) should be used to prevent a potential catastrophe.
LEAKING CYLINDERS OR VALVES
Several types of leak scenarios may occur with the 20-pound LPG cylinder commonly used for barbecues. Leaks may occur involving the cylinder or the valve assembly. Cylinder seams may leak because of fatigue, mechanical damage (e.g., strikes, dents, scores, for example), or manufacturing defects.
 This firefighter, in full PPE with SCBA, is assessing the leak with a meter. |
Valves may be defective, allowing product to escape even though the valve handle is in the closed position. The valve may have been improperly installed and is not correctly seated in the cylinder. Leaks caused by defective seams and improperly seated valves may not be readily controlled and may necessitate that the LPG within the cylinder be burned off.
You can temporarily stop the leaky valve with a plug, but it is best to burn this one off. Plugging or allowing frost to form over the leak (autorefrigeration) is just a temporary fix. You haven’t really solved the problem until the cylinder is empty and the hazard has been removed.
Leaks in damaged cylinders also ordinarily cannot be stopped. If the damage is severe enough, the cylinder may be empty before you arrive on-scene. If that is the case, check low-lying areas, and disperse any vapors that may be present.
OVERFILLED CYLINDERS
The next type of leak occurs when cylinders are overfilled. Although the newer generation of cylinders equipped with an overfill prevention device (OPD) have reduced the occurrence of cylinder overfills, many “old” cylinders without the OPD feature can still be found. Because of excessive pressure within the cylinder, the pressure relief valve operates, and the excessive pressure is released. This is what the pressure relief valve is designed to do, but most consumers are not aware of this. Sometimes this pressure relief valve may operate while the newly filled cylinder is being transported home in the back seat of a car. This is exciting to say the least to the person driving the car.
The pressure relief valve on recently filled cylinders stored in direct sunlight on hot summer days may also operate. The caller most often will report that a loud hissing sound was heard prior to detecting an odor of gas. Because of the increased temperature, the pressure inside the cylinder increased and caused the pressure relief valve to operate.
 Members dispersing vapors at a leaking cylinder. |
Our response to this type of incident may require vapor dispersal, inspection of low-lying areas and basements with meters, and bleeding off any excessive product within the cylinder. As stated earlier, when LPG vapor is found in a basement, it is imperative to remove sources of ignition and to ventilate. Use PPV.
USER ERROR
Another leak that occurs involves user error. Valves may be cross-threaded or loosely connected. Lack of proper maintenance and insect nests inside supply lines or pressure relief valves may cause minor leaks as well. Check for any of these problems; correct them if you can. If you can’t, direct the user to the local service center. Positive public relations can go a long way.
Flaring is a safe and easy-to-use alternative to opening the valve and allowing the product to disperse into the atmosphere while keeping your fingers crossed that the product doesn’t find a source of ignition (see sidebar above). Although it isn’t likely that the product will find a source of ignition, especially if fog streams are used to disperse the vapors, the possibility of its occurring can easily be eliminated.
Flare kits consist primarily of a put on left (POL) valve, a hose, and some sort of a flare stand. A variety of fittings and hand tools complete the kit (photo 1). It is a relatively simple and safe operation. Communication is the key to a safe and successful operation.
 (1) Complete burnoff kit. (Photos by author.) |
The bottom line with leaking cylinders is that they present a problem as long as they contain product. Operations at these incidents don’t have to be difficult. Investigations should be thorough. Evacuation should be done as necessary. The type and severity of the leak are the keys to selecting the strategy and tactics to be used.
As with all gas-related emergencies, members should wear full protective clothing and SCBA. Engine companies should be prepared to secure a water source and stretch handlines. All departments should have a flammable gas meter to assess the severity of and pinpoint leaks. If your department doesn’t have a flare kit, know whom in your area you can call that does. Coordinate with your local propane marketer and distributor for further assistance. ■
FLARING
Flaring is conducted primarily by two separate teams under the supervision of a team leader. The “cylinder” team, as the name implies, is responsible for operations at the cylinder. The “torch” team is responsible for operations at the torch or flare. Coordination is the key to a successful operation. Listed below are the responsibilities of each team and the team leader.
Cylinder Operations Team
 (4)Stabilized cylinder with POL valve in place and closed. |
• Pinpoint the leak’s location, and assess its severity.
• Connect and control the put on left (POL) valve.
• Stabilize the cylinder (photo 4).
• Open valve and begin vapor burn.
• Invert the cylinder to promote liquid burn (photo 5).
• Purge the hose and torch assembly on completion of burnoff.
• Maintain communications with the team leader.
 (5)Inverted cylinder promoting liquid burn. |
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Torch Operations Team
• Set up the torch in an appropriate area that is free of overhead obstructions (trees, power lines, for example) and clear of exposures.
• Ensure that the flare is upwind of the leaking cylinder.
• Ignite and place flare.
• Monitor conditions and status of the burnoff.
• Maintain communications with team leader.
 Burnoff in progress. |
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Team Leader
• Coordinate operations among the torch, the cylinder, and the incident commander.
These teams are supported by an engine company that has secured a water source and stretched handlines as required. The handlines are used to protect the members operating at the scene and to disperse any vapors present. For most operations, one 1¾-inch line at the cylinder and another at the torch will suffice. Depending on the severity of the leak, it may be necessary to stretch two lines at the cylinder.
Evacuation should be done as necessary, according to the severity of the leak. Usually, evacuation will be limited to the structures directly exposed and the immediate area around the torch. Remember to keep wind direction in mind.
Burning off a full 20-pound cylinder using 100 feet of ¾-inch hose takes about 10 to 15 minutes. Although this size hose is awkward to store and maneuver, it allows for a reasonably quick operation. If care is taken in deploying and stowing, generally there are no problems. The length of the hose allows you to place the torch a safe distance from the leaking cylinder. An extra length of hose can be connected as necessary. The burnoff begins by burning vapor.
After a vapor burn is established, some cylinders can be inverted and a liquid burnoff initiated. However, this tactic can be used only with older cylinders without an overfill prevention device (OPD). Cylinders with an OPD will shut off when the cylinder in inverted, thereby stopping the flow of liquid. Burning liquid is faster than burning vapor and cuts down on the total time of the operation. It is vital to monitor all connections during the liquid burn. If a liquid leak is detected, sweep the area with a fog pattern to disperse the product and return to a vapor burn. Continue to disperse vapors at the sight of the leak. The system our fire department uses necessitates only two connections, one at the cylinder and one at the torch. When connections are properly made and are sufficiently tight, leaks ordinarily don’t occur. The team leader closely monitors the entire burn. If a problem develops, the operation can be quickly stopped by closing the POL valve at the cylinder.
Flaring a 20-pound LPG cylinder is a fairly simple operation. When properly performed, flaring is a safe and efficient way to mitigate the leak.
