Burning Speed

Burning speed it the speed at which a flame travels through a combustible gas mixture.

Burning speed is different from flame speed. The burning speed indicates the severity of an explosion since high burn-ing velocities have a greater tendency to support the transition from deflagration to detonation in long tunnels or pipes. Flame speed is the sum of burning speed and displacement velocity of the unburned gas mixture.

Burning speed varies with gas concentration and drops off at both ends of the flammability range. Below the LFL and above the UFL the burning speed is zero.

The burning speed of hydrogen at 8.7-10.7 ft/s (2.65-3.25 m/s) is nearly an order of magnitude higher than that of methane or gasoline (at stoichiometric conditions). Thus hydrogen fires burn quickly and, as a result, tends to be relatively short-lived.

Hydrogen burns with greater vigour than gasoline, but for a shorter time.