Norman, John. The Unpredictable Propane Barbecue. Firehouse. May, 1989.
Abstract: This article explains the procedures for fighting propane
ignited fires. Most grills operate with liquid petroleum gas (LPG), which
consists mostly of propane, but will also contain butane and ethane. Propane
has a wider explosive range than gasoline and vaporizes at 44 degrees Fahrenheit.
Liquid Petroleum Gas will ignite when certain conditions are met. These
conditions are easily fulfilled inside a structure and the slightest source
of ignition, a static spark or pilot light, can cause a vapor/air explosion.
Many incidents of propane/air explosions have prompted jurisdictions to
ban indoor storage of LPG.
Propane cylinders apply pressure to propane, compressing the gas to its
liquid state. This process decreases its volume to 1/270 of its original
volume. When the pressure is released, the liquid immediately begins boiling
to a gas and expands to its gas size. This means that one quart of liquid
propane will evaporate to 270 quarts of propane vapor. If this process occurs
inside an enclosed area, the slightest spark will ignite the propane.
When firefighters arrive at the scene, their main concern is a BLEVE(boiling
liquid-expanding Vapor explosion). A BLEVE occurs when the temperature of
the propane cylinder increases. This causes the propane to evaporate, rising
to the top of the cylinder, and increasing the pressure at the top of the
cylinder. The cylinder will reach its failure point and explode. The energy
released is powerful and can cause the cylinder to launch in any direction.
This is a concern for firefighters who may find themselves in the path of
the cylinder. Firefighters should protect themselves and civilians first
before extinguishing the fire. The structure or house should be evacuated,
including adjacent homes. Firefighters should approach the flames with caution,
taking cover behind anything that may protect them the BLEVEing container.
From this point on, the operation should be taken slowly to prevent any
re-ignition of the fire.
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