If the gas in the mixture is insufficient or the supply air is too much, the heat released by the combustion is not reached and the combustion is stopped.

The smallest and largest volumes of gas content in the gas mixture, within which a flash or explosion may occur, are called the lower and upper limits of explosion.

 
Burning temperature
Explosive limits, volumetric% explosive mixture
Lower
Upper
Bhutan
365° C
1.50 %
8.50 %
Hydrogen
510° C
4.00 %
7.50 %
Methan
595° C
5.00 %
15.00 %
Propane
470° C
2.10 %
9.30 %