Muffler Ignites Plastic Fuel Tank
The advisability of using 1 1/2-inch lines instead of booster lines for the initial attack on motor vehicle fires was underscored at a pickup truck fire in El Paso, Texas.
Engine 15, a 750-gpm pumper with a 600-gallon booster tank and 30 gallons of aqueous film-forming foam (AFFF), was dispatched to a pickup truck fire at 3:50 p.m. last August 16. A moderate amount of smoke was rising between the cab and the bed. No flames were visible.
Two 100-foot, 1 1/2-inch lines were ordered into operation, one to each side of the truck. Shortly after water was applied, a small ground fire was seen beneath the midsection of the pickup. Seconds later, there was a tremendous increase in the size and intensity of the fire. AFFF was ordered educted into the hose lines and the fire was extinguished in one to two minutes. Booster lines were brought into action for overhaul and washdown and the 1 1/2-inch lines were shut down.
A critique of this incident indicated that had booster lines been used initially. the fire in all probability would have done substantial damage to the vehicle. The fire fighters would have been driven back, allowing a larger area of flame involvement. In addition,, the application of AFFF permitted immediate extinguishment of the rapidly developing fire and minimized further damage to the truck.
Investigation revealed that the muffler on the 1974 Dodge crew-cab pickup had ruptured. This allowed the hot exhaust gases to impinge on the plastic fuel tank. The heat burned a hole in the top of the fuel tank and ignition took place. This accounts for the moderate showing of smoke and the absence of an initial ground fire.
The fire enlarged the hole and heated the surrounding plastic. The eventual collapse of the tank caused the entire contents to flow beneath the vehicle. This accounted for the dramatic increase in the intensity and size of the fire.
This seemingly minor incident is excellent confirmation of the advisability of using larger diameter lines on vehicle incidents rather than relying on booster lines.
Plastic tank information
Interviews with Chevrolet, Ford and Dodge dealers developed information on the use of plastic fuel tanks.
There are no factory-installed plastic gasoline tanks on any Chevrolet models. However, auxiliary fuel tank installations in El Paso are contracted out and the tanks may be either metal or plastic with capacities of 19 to 20 gallons. Since 1973, all fuel tanks on Chevrolet pickups are frame-mounted and are no longer placed behind the seat.
All F-series Ford trucks (1/2, 3/4, 1 and 1 1/2-ton) are factory-equipped with metal fuel tanks. The L-series Ford trucks (2 1/2 to 4-ton) may have a 25gallon plastic fuel tank. LTDs with the extended mileage package have a 9gallon plastic fuel tank on the trunk.
Broncos come from the factory equipped with a frame-mounted metal fuel tank. Auxiliary tanks may be either metal or plastic, depending on customer preference. On all, ’74 through ’77 model Ford trucks, the fuel tanks are frame-mounted and no longer behind the seat.
Dodge factory practice
Plastic fuel tanks are not installed on Dodge autos or station wagons. However, ’74 through ’77 pickups of 1/2 to 1 1/2 tons generally have factory-installed plastic fuel tanks. The tank capacities are 18, 20, 26 and 36 gallons, and the tanks are from 46 to 51 inches long. They are mounted on the frame in front of the rear wheel on the driver’s side. Dodge vans may or may not have plastic tanks.
A superficial survey of recreational vehicles at these dealers revealed about a 50-50 ratio of metal to plastic fuel tanks. The most distinguishing feature was that the larger recreational vehicles generally had metal tanks.
Reports from Ford and Chevrolet dealers indicated that the plastic fuel tanks are more expensive than metal tanks and the cost may govern whether or not a more widespread use of plastic tanks is in the offing.