Safety & information: Fuel fires

Safety & information:

Fuel fires

The danger of a gasoline, or petrol, fire is always present in an automotive workshop. Most automobiles carry a tank, often with large quantities of this type of fuel on board, more than sufficient to cause a large and very destructive and explosive fire.

Fuel vapor

Liquid fuel vaporizes rapidly, especially when spilt, and the vapor is extremely easy to ignite. Because fuel vapor is invisible and heavier than air, it can spread unseen across a wide area and a source of ignition can be quite some distance from the original spillage. Fuel can even vaporize from the cloths or rags that are used to wipe up liquid spillages, and these should be allowed to dry in the open air, not held in front of a heater element. Any spark, any naked flame, even a lit cigarette can start an explosive fire.

Flammability range

Fuel vapor has a wide range of flammability. When mixed with air it will readily ignite if the ratio of fuel is 1.4% - 7.6% of the mixture, so it is especially dangerous at quite low concentrations.

Spillage risks

Spills frequently occur when technicians remove a fuel tank sender unit, which is often located on the side of the fuel tank, without first emptying the tank safely. Spills also occur when fuel lines are damaged and are being replaced, or when fuel systems are being checked, or when fuel is being drained into unsuitable containers or containers that are too small for the amount of fuel being drained.

Draining fuel

If there is a possibility of fuel spillage while working on a vehicle then you should first remove the fuel safely. Do this only in a well-ventilated, level space, preferably outside in the open air. Make sure that all potential sources of ignition have been removed from the area, and disconnect the battery on the vehicle. Do not drain fuel from a vehicle over an inspection pit. Make sure that the container you are draining into is made of a suitable fuel-resistant material, and that it is large enough to contain all of the fuel in the system being drained.

Use a fuel retriever

Always use a fuel retriever, preferably removing the fuel through the filler neck, as this will minimize the chance of sudden gross spillage occurring. You may need to use narrow bore hoses or adaptors to drain fuel lines or to bypass anti-spillage devices. Check your vehicle workshop manual for details on how best to drain the fuel from the vehicle you are working on.

Repairing a fuel tank

Never weld anywhere near a tank or any kind of fuel line. Hot work on a tank itself is a job for specialists, because an empty fuel tank can still contain vapor and therefore even more dangerous than one full of liquid fuel. Do not attempt to repair a tank yourself.