What are backfire flame arrestors designed to prevent?

Backfire flame arrestors are specifically designed to prevent the ignition of gasoline vapors in the event of a backfire. A backfire occurs when unburned fuel in the engine's intake manifold ignites and creates a flame that could potentially escape from the engine. Without a flame arrestor, this flame could ignite gasoline vapors, leading to a fire or explosion in the confined space of the engine compartment. The flame arrestor functions as a safety device that allows gases and vapors to pass through while preventing flames from exiting the engine area. This critical safety feature is particularly important in boats, where flammable materials are present, ensuring that the chance of a hazardous ignition event is minimized.