Standalone Natural Gas Leak Detector AC 220V Relay NC NO Network Output Fire Sensor First determine the gas density in the air, then mount this detector near the gas source within 2.5m. (Note: The density of coal gas and natural gas is lower than that of air, so they are at a higher level. The density of LPG is lower than that of air, so it is at a lower level) Make sure the power supply and signal cables are properly connected to the detector, turn on the power. Then the device will start as follows: 1. Warm-up state. The red LED indicator flashes once and the speaker makes a sound. 2. Normal state. The green LED indicator flashes once per minute for about 3 minutes. 3. Monitoring status. The green LED indicator is constantly on. To see if the detector is working properly, press the S1 button on the PCB. If the red LED indicator is on and the speaker makes a sound, it means the detector is working properly. When the gas density reaches 6% LEL, the LED indicator turns red and flashes,