Positive Air Shutoff | Issue 04-2018
Positive air shutoffs are designed to keep a diesel engine from over-revving and “running away”. This is a unique hazard with diesel engines because they do not require a spark for ignition and can continue to burn hydrocarbons in the air even when the diesel fuel is exhausted or the key is removed. As a result, positive air shutoffs are an important barrier to prevent the over-revving and subsequent explosion of the engine.
Such an explosion could result in injury or be the source of ignition for a larger fire or explosion.