It was 25 years ago, on July 5, 1973, that a propane tank car being off-loaded in Kingman, AZ, caught fire, resulting in a BLEVE - boiling liquid expanding vapor explosion - that killed 11 Kingman firefighters and one civilian. Captain Wayne Davis is the only firefighter in the area who was at...
To access the remainder of this piece of premium content, you must be registered with Firehouse. Already have an account? Login
Register in seconds by connecting with your preferred Social Network.
Complete the registration form.
Every liquefied gas container has an approximate 20% vapor space above the liquid in the tank to allow for expansion of the liquid to vapor within the tank during shipping and storage. This is the most dangerous place for flame impingement to occur because there is nothing to absorb the heat but the metal itself. Steel does not absorb heat well so when temperatures reach above 400F, the integrity of the tank is quickly in jeopardy.
National Fire Protection Associa-tion (NFPA) statistics show that pressure tanks can fail from flame impingement within the first 15 to 20 minutes of the first flame exposure. It is estimated that the Kingman fire burned for eight minutes before firefighters arrived and an additional two minutes before the first water was applied from the engine booster tank to cool the propane rail car. The BLEVE occurred at 2:10 P.M., just 19 minutes after the first flame impingement on the top of the tank. (Flame impingement on the liquid level is a somewhat less dangerous situation because the liquid will absorb the heat and protect the integrity of the tank. However, the increased heat will cause the already boiling liquid to boil faster, causing the pressure inside the tank to increase.)
Firefighters' tactical objectives at Kingman were to provide water to cool the tank and prevent an explosion. An engine with a 1,000-gallon booster tank was positioned 75 feet from the rail car and two one-inch booster lines were put into service to cool the tank shell. (The water flow from a one-inch booster line is about 30 gpm.) If water is applied effectively to the point of flame impingement, the temperature of the shell cannot go above 212F, well below the failure temperature of the steel. This operation requires large quantities of water. The NFPA recommends that an uninterrupted water supply of 500 gpm be applied the surface of the tank for cooling.
While the first firefighters attempted to cool the rail car from the booster tank of the engine, others began laying two 2 1/2-inch lines to the hydrant 1,200 feet away to supply a deluge gun located 50 feet from the burning tank car. The first 2 1/2-inch hose lay was completed but the firefighters ran out of hose for the second supply line. The first line was being charged when the explosion occurred. Thirteen firefighters were within 150 feet of the burning rail car when the blast occurred. Eleven of them died from severe thermal burns - one career member and 10 volunteers. A 12th firefighter was taken to the hospital in critical condition but survived.
Protective equipment typical for firefighters at the time was cotton duck with wool linings and helmets made of polycarbonate plastic. This was the type of protection worn by the Kingman firefighters. It is reported that at the time of the explosion some firefighters had full protective gear, while others wore only coats and helmets or just coats. Those firefighters killed had the coats and their street clothes burned off of their bodies by the fire and radiant created from the explosion.
The tank broke into pieces from the force of the blast and one half of the tank bounced end over end westward down the tracks, landing 1,200 feet from its original location on the siding. The other portion of the tank tore along the welds and flattened out on the ground. A ground-level fireball ensued and extended 150 to 200 feet in all directions from the center of the blast. This was followed by a large mushroom cloud of flame extending several hundred feet into the air, measuring 800 to 1,000 feet in diameter.
Fireball flame temperatures can reach well over 3,500F. The fireball and radiant heat set five buildings on fire, including the tire company, restaurant, truck stop and gas company office building, and started several brushfires. Radiant heat was so intense that it caused the relief valve on the 30,000-gallon storage tank to activate. The released vapors, however, did not ignite; once the pressure was relieved, the valve closed and remained closed from that point on.
Following the explosion, calls for mutual aid went out to the Lake Havasu City, Mohave Valley and Bullhead City fire departments. There was a catastrophic-disaster clause in the county's mutual aid agreements and when the explosion occurred an all-hands call went out to the fire departments in the county. Chiefs of the Lake Havasu City and Bull Head City departments set up a command post at the Kingman Fire Station 2. Responding mutual aid companies were assigned to extinguish the numerous fires, the last of which was brought under control at 5:30 P.M.