Intelligent control, check by themselves, prevent from wrong alarm, exterminate missing alarm , ... design to induct coal gas, natural gas and petroleum gas.3.Intelligent control, check by themselves, prevent from wrong alarm, exterminate missing ... .5%(coal gas, petroleum gas) 0.1% to 0.3%( natural gas) 3. Voltage: 9-15v DC 4. Operational temperature: -10 to ...