... toxic gases. It is suitable for combustible and toxic gas leakage detection in underground pipe or mines, and keeps ... protection function;High concentration protection for combustible gas;Self test for the combustible gas sensor;Low battery indication;Replaceable sensor module ... Explosive proof housingGas Detected:combustible gas(CH4,C3H8,H2)and toxic gas, oxygen, Other rare toxic gas like NO,PH3,NH3, ...