Deflagration

A deflagration ( burning of Latin deflagrare =) is a fast combustion process, in which the explosion is caused only by the emerging and expanding gases. Reproduction is by the heat released during the reaction heat, in other words, the ignition of the unburned mixture is carried out by heating the mixture in the flame front.

In a deflagration, the combustion pressure is (in air under atmospheric initial conditions ) usually on the order of 1 MPa (10 bar ), but may depend on the fuel higher ( for example in nuclear reactions, see also supernova ). The combustion takes place with a speed which is less than the sound velocity in the burning medium.

At higher speeds, it is called a detonation, with the combustion mechanism converts from the heating of the unburned mixture to shock wave- induced combustion. Detonations in pipes may have pressures result in excess of the blast pressures at deflagrations many times. Upon detonation, the pressure wave is superimposed with the resulting in the explosion of reaction volume caused by temperature expansion.

In German-speaking countries is called deflagration also automatically continuous decomposition of a solid called, which can be accompanied with a heat or gas release.

In a deflagration would explain why a decomposition reaction in the absence of oxygen.

Deflagration

Of a deflagration is used when it is true, the combustion reaction by a volume expansion, but not to a relevant pressure build-up. The velocity of propagation and the expansion or compression of the produced gases associated therewith can here a rate of 0.01 - assume 1 m / s. The previous definition of a maximum pressure of less than 100 kPa (1 bar ) is not longer in use.

Examples include explosions in furnaces, where in the absence of pre-purge ( unburned fuel) or by incomplete combustion ( carbon monoxide formation) can be a dangerous explosive atmospheres may occur. If this atmosphere ignited by a hot surface or in repeated burner start, creates a pressure wave that is relaxed towards the chimney and where appropriate a blast doors partly. Since the combustion chambers are not usually designed for a pressure load, explosions can cause considerable damage.