Minimum Ignition Energy

MIE depends on type of gas and concentration
8.0% volume methane is "sweet spot" for stoichiometric combustion of methane
Although flammability range for CH4 is 5 - 15%, concentration where it is easiest to ignite is 8% by volume
At 25° C, 1.0 atm, takes 0.3 mJ to initiate explosion chain reaction
Static electricity "zap" when insert key into ignition = 5.0 mJ
MIE for other combustible gases much lower

Combustible sensor electrical safety and performance requirements

Important standards defining combustible sensor performance:
- Canadian requirements: CSA 22.2
- United States: UL 913
- ATEX: EN50018
- Harmonized IECEx: IEC60079-1