Did you know that flammable vapors in the air can cause diesel engines to potentially overspeed and damage themselves under idle or lightly loaded conditions? Shutting the engine off won’t help — as long as the vapors are drawn into the air intake, the engine could keep running.

This problem has been noted for many years and was especially critical for fuel tankers during tank filling operations. Current controls on vaporous-organic compound emissions have reduced or eliminated this particular problem in some areas, but fire departments face a similar, more serious, problem when responding to fuel spills where large volumes of flammable vapors are present in the atmosphere.

The best solution is to position vehicles upwind and uphill of fuel spills at a sufficient distance to avoid the vapor cloud. Liquid spills then can be sealed with a blanket of foam. If alcohol-based fuels are involved, departments need to use alcohol-resistant foam, such as AR-AFFF.

This feature offers a variety of short tips and facts about apparatus specifications, maintenance and testing. Look for it every month. Submissions of 150 words or less are welcome from our readers, subject to editing. Send them to Senior Editor Chris Cavette at cavettes@ix.netcom.com