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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.