... to induct coal gas, natural gas and petroleum gas.3.Intelligent control, check by themselves, prevent from wrong alarm, exterminate missing alarm , be ... 5.Easy installation Specification 1. Kinds of gas: coal gas, natural gas and petroleum gas 2. Alarm density: 0.1% to 0.5%(coal ... gas, petroleum gas) 0.1% to 0.3%( natural gas) 3 ...