There are two main hazards that everyone needs to be aware of when transporting flammable liquids such as gasoline.
Many of you probably remember the first time you saw a “safety can” for carrying flammable liquids. Equipped with a spring-loaded cap on the pouring spout, it was designed to prevent accidental spillage or escape of vapors when not in use. It was a big step forward in the development of a convenient and safe container for handling or storing flammable liquids.
The hazard of carrying safety cans in closed compartments was first discovered when the back-end of a police car exploded as the officer started to use the radio transmitter. Owners of vehicles equipped with a mobile telephone or radio who have carried a container of gasoline in the trunk compartment with the transmitter have reported similar cases.
Extensive tests were carried out to determine the limitations, weaknesses, and undesirable features of the various types and styles of portable flammable liquid containers.
Various types of cans react differently to atmospheric changes and hydrostatic pressures. Through experiments it was proven that when a closed safety can was subjected to heat, expansion of the fluid inside would build up enough pressure to force vapors out past the cap. In a sealed compartment—such as an automobile trunk—the vapor would ultimately reach explosive proportions. The spark that would set off such an explosion could come from a switch or relay in a radio transmitter, the electric motor of a gauger’s centrifuge, or a simple short-circuit in the taillight wiring of a car.
Using the trunk of a junked automobile at a salvage yard, tests were filmed that showed conclusive evidence of the hazard of hauling flammable liquids in a closed compartment of an automobile. A full, safety-type gasoline can with spring-loaded cap was placed in the trunk of the car on a warm August day. A 150-foot length of plastic tubing extended from the trunk to an explosimeter where a flammable mixture was recorded in less than three minutes after the trunk lid had been closed. A welder’s friction-type torch lighter had been mounted inside the compartment, with a fine wire attached to the handle and extending to the observation point. One pull of the wire was usually sufficient to ignite the vapors on each of the several tests, and explosions resulted in varying degrees of violence. The longer the ignition was delayed, the greater the resulting explosion. The experiments stopped far short of the maximum explosion that would occur if the atmospheres of the trunk were saturated—a blast that would destroy a car, and under normal conditions and very likely kill or seriously injure the driver and passengers. Without going to this extent, the tests provided convincing proof that so-called safety cans, or any other container, cannot be transported or stored safely under such conditions. In fact, the next time, you see someone fill a “safety can” and stow it in the trunk of a car—you might either warn the driver, or get the heck away from his bomb!
There have been a number of vehicle fires that occurred when gasoline cans were filled while in the bed of a truck or trunk of a car. The process of filling the container while in the truck bed or trunk may allow static electricity to build up. While the container is filling, fumes are being pushed out of the container and dispersed in the bed or trunk. A small static electricity spark is all that it takes to set off this bomb. When filling containers with flammable liquids such as gasoline, the container should be placed on the ground or bonded to a ground so that static electricity cannot be built up.