Is It Time to Change Our Training Yet? Part 3: Fuel Tanks
A melted gas tank following a vehicle fire. (Photo: Lee Junkins)
Lee Junkins, Midsouth Rescue Technologies
In the early 1970s environmental standards forced automakers to change their fuel systems drastically, earlier vehicles used leaded gasoline, and the vapors were simply vented through a small hole in the gas cap into the atmosphere. The new standards forced them to use unleaded gasoline and sealed fuel systems that would no longer vent into the air. Since 1970 all fuel systems are vented through a charcoal filter system. The vapors are then routed back into the engine to be burned before being released to the atmosphere; this is called evaporative emission control.
With these vapors being in a sealed system and constantly changing pressures as they expand and contract with the change in temperatures, some part of the system must be flexible.
Today’s plastic gas tanks have become the answer to all three of these problems. The polyurethane and polyethylene used in most of these tanks is six layers thick, making them highly resistant to punctures. It’s also flexible allowing for expansion of vapors and bending during a crash. Most firefighters know the most vulnerable part of a metal tank is the seams, being molded these tanks are seamless. Also being molded they have no edges to snag on and rupture, when being pushed forward in a crash. By federal standards all edges and corners must be rounded. Economic wise the six layered polyurethane tank is still lighter than the same size metal tank.
As we seen in part 1 of this series, today’s vehicles, (even the gas tanks), are literally built to wreck but as we will see here not one is built to burn.
Like all plastics, polyurethane melts at very low temperatures and with these tanks holding from 15 – 28 gallons of gas, a person can only imagine the results if one dropped its heated load under a burning vehicle. Yet today we are still teaching firefighters to approach the vehicle diagonally to the corner, putting them right in the ring of fire, if this was to happen.