Depending on the minimum ignition energy of the gas,
the gases are classified in gas groups.
GROUP I Methane (mining)
GROUP IIA Gases with minimum ignition energy more than 80μJ.
e.g. Propane
GROUP IIB Gases with minimum ignition energy from 45 to 80μJ.
e.g. Ethylene
GROUP IIC Gases with minimum ignition energy less than 45μJ.
e.g. Hydrogene
View safety characteristics of flammable gas and vapours here