S5.5 Fuel spillage: Barrier crash. Fuel spillage in any fixed or moving barrier crash test shall not exceed 1 ounce by weight from impact until motion of the vehicle has ceased. And shall not exceed a total of 5 ounces by weight in the 5-minute period following cessation of motion. This standard specifies requirements for the integrity of motor vehicle fuel systems. The purpose of this standard is to reduce deaths and injuries occurring from fires that result from fuel spillage during and after motor vehicle crashes, and resulting from ingestion of fuels during siphoning.
S4.2 Flammability of Interior Materials: When tested in accordance with S5, materials described in S4.1 and S4.2 shall not burn, nor transmit a flame front across its surface, at a rate of more than 4 inches per minute. This standard specifies burn resistance requirements for materials used in the occupant compartments of motor vehicles. Its purpose is to reduce deaths and injuries to motor vehicle occupants caused by vehicle fires, especially those originating in the interior of the vehicle from sources such as matches or cigarettes. This test is normally done as a horizontal burn test rather than the more realistic burn test.
Fuel-injected engines require fuel to travel through fuel lines at high pressure. Due to the high pressures involved, even a small compromise in a fuel line can result in a large amount of fuel escaping from the fuel system. Failure in a line may be caused by the location or routing of the line. Failure in a line may also result from the use of inappropriate materials. The location and composition of the fuel lines is critical to the overall fuel system integrity of a vehicle.
Most fuel-injected engines have electric fuel pumps. It is critical that these pumps shut off in the event of a collision. If a fuel pump does not shut off following a collision, the pump will continue to circulate gasoline through the fuel system, providing a constant source of fuel for any resulting fire. There are many different types of mechanisms that are used to shut off the fuel pump in the event of a collision. The type of mechanism used, and the location of that mechanism, may play a significant role in whether the fuel pump does, in fact, shut off following a collision.
Defects in the design and placement of fuel tanks have been among the most widely publicized fuel system defects, including the Pinto cases and the General Motors "sidesaddle" trucks with fuel tanks located outside the frame rail. Fuel tank defects may involve the location of the tank on the vehicle, the placement of the tank near objects that can potentially puncture the tank, the material from which the tank is constructed, the actual construction of the tank including improper welds, and the failure to adequately shield the tank.
Siphoning It is possible for fuel to siphon from a fuel tank after a collision, providing a continuing source of fuel for a vehicle fire. Siphoning is the flowing of fuel through a point of compromise in a fuel system due to gravity. Gas can siphon from the fuel system at a very high rate, providing a substantial amount of fuel for a vehicle fire. Although manufacturers have known of the danger of fuel siphoning for many years, and although anti-siphoning devices are inexpensive, anti-siphoning devices are not incorporated on many vehicles presently on the highway.