... sorts of combustible gases, such as coal gas, liquid petroleum gas and natural gas, carbon monoxide and monitor automatically.Specification:* ... than 3 minutes400PPM: ImmediatelyCoal gas: 1000~5000ppm,Liquid petroleum gas: 1000~5000ppm,Natural gas: 1000ppm~5000ppm*.Responding time: Gas ≤30S*.Alarm output: ... do not use anything can make fire, e.g. lighters, matches, etc.4. Avoiding open or close the ...