A combustible gas is one that will burn when mixed with air (or oxygen) and ignited. Combustible gas detection includes that of natural gas, methane, butane, propane and hydrogen.Detecting hydrocarbon and nonhydrocarbon combustible gasses requires approved and reliable technology. Typically, most combustion reactions involve the burning of organic materials containing carbon and hydrogen. Combustible gas detection and safe working practices Flammable or combustible gas detectors can be used to trigger alarms if a specified concentration of the gas or vapour is exceeded. This can provide early warnings of a problem and ensure people’s safety. But! A detector does not prevent leaks or indicate what action needs to be taken. They are not a substitute for safe working practices or maintenance.