This 502 gas detector complies with the following directives and standards: LVD Directive 2014/35/EU EN 50194-1:2009 **Fault Mode:** In case of a breakdown, the alarm will no longer function normally. At this time, the STATE light will illuminate yellow and remain constantly lit, the green POWER light will remain constantly lit, and the ALARM light will not light up. **Specifications:** Operating Humidity: <97% RH Storage Temperature: -25°C ~ 55°C Product Dimensions: 69*72*121mm Detectable Gas: Natural gas (methane), Liquefied Petroleum Gas (propane, butane), Artificial gas (alkane, olefin, aromatic carbon) Sensor: Solid-state gas sensor Alarm Concentration: 3% LEL ~ 20% LEL Warm-up Time: 3 minutes Operating Voltage: AC100V ~ AC240V Frequency: 50/60Hz Rated Power: <2W Alarm Volume: ≥85dB Material: ABS Operating Environment: -10°C ~ 50°C **Power On:** Upon power-on, the unit emits two “DIDI” signals, the blue POWER light remains constantly lit, and the red ALARM light flashes twice. **Warm-up Mode:** Within 3 seconds of power-on, the unit enters warm-up mode (180 seconds). The green POWER light remains constantly lit, the STATE light flashes green, and “-” flashes on the display. Do not perform any other operations during warm-up. **Detection Mode:** After completing the warm-up, the alarm enters detection mode (normal mode): “0” is displayed, only the green POWER indicator remains constantly lit. **Warning Mode:** Numbers 1-9 and A are displayed. Different alarm states are indicated: 1-2: Green POWER light remains on, no alarm sound. 3-5: STATE and ALARM lights flash red, low alarm sound (“DI…DI…”). 6-9: STATE and ALARM lights flash red, urgent alarm sound (“DI DI DI…DI DI DI…”). A: High gas concentration detected (≥9% LEL), STATE and ALARM lights flash rapidly, urgent alarm sound.