The Gas Leakage Detector can be used for detecting combustible gas, e.g. natural gas, LPG and etc. When the leaking gas accumulates up to the limit value (10%+/-2% LEL), the detector can sense it with LED flashing and built-in siren sounding, at the same time, send out signal to the control panel and/or activate the Solenoid Valve, so the Valve can cut off the gas source within 1 second.