Diesel engine overspeed or runaway is a known issue in the repair industry that could occur during or right after an engine repair. Runaway could also occur if the engine is surrounded by a flammable gas or hydrocarbon vapor. During a runaway, the engine RPM’s will reach a point where the intake and exhaust valves are open at the same time allowing the vapor to ignite in the intake manifold. This type of back fire can ignite the gaseous vapors surrounding the truck. The results will always be catastrophic (see OSHA Fact Sheet DSG FS-3589-10 2012 Internal Combustion Engines as Ignition Sources).
Fire trucks often drive into areas where flammable vapors or gases exist during accidents and other emergency situations. Firemen wear protective gear to protect themselves from the fire, but their fire trucks are not always protected from being the ignition source which may cause an explosion. Installing an air intake shutoff valve on your diesel engine will help prevent it from becoming an ignition source.
Air intake shutoff valves combined with an engine RPM monitoring system will detect the RPM overspeed and shut off the intake. This effectively stops the flow of air and external fuel source and shuts the engine down before it can ignite the gases. Systems can be set up for automatic shut down if overspeed occurs while in road mode to protect while arriving on scene and then can be switched to manual activation once the unit is shifted into pump mode to allow the operator to make sure personnel is safe before shutting down the engine.
Check with your Fleet Manager to see if your trucks are protected. Visit www.dieselsafety.com for more information.
