Why Do You Need to Turn Off the Engine When Refueling?

[StReid]

Turning off the engine during refueling is to prevent ignition and explosion. Gasoline is an electrolyte, classified as a flammable substance with high volatility. When refueling at a gas station, the concentration of fuel vapor mixed with air around the fuel tank increases significantly. Combined with the fact that gas stations are already dense areas of fuel vapor, it becomes extremely easy to reach the explosive limit. Once the explosive limit is reached, even static electricity—let alone an open flame—can trigger an explosion. If the engine is left running, it continues to operate at high speed, and the vehicle's electrical current flows normally. In this state, any electrical leakage could be extremely hazardous. Additionally, while the engine is running, the exhaust pipe continuously emits tailpipe emissions, often accompanied by sparks. If gasoline were to drip onto the exhaust pipe at this moment, it could easily catch fire.