TABLE OF CONTENTS Detonation of a flammable gas air mixture may occur by direct initiation of detonation by a powerful ignition source or by transition from deflagration.
The transition from deflagration to detonation requires a strong acceleration of the flame front. It occurs in pipelines but is very improbable in vessels. The transition from deflagration to detonation is a complex process. The properties of the detonation, however, are fairly well defined and depend essentially on the properties and condition of the unburnt gas.
A general account of the pressures which may be generated by detonation inside a plant has been given in Section 17.2. In practical terms, the peak pressure ratio P 2/ P 1 resulting from a detonation of a hydrocarbon air mixture in a containment such as a vessel is about 20:
This is the order of pressure rise, for example, in the experiment reported in Table 17.7.
The transition from deflagration to detonation was discussed in Sections 17.2 and 17.5, where information was given on the run-up length to detonation and on the pressures exerted both on the pipe wall and on the end flange.
Accounts of detonation in pipes have been given by a number of workers, including Craven and Greig (1967), Munday (1971b) and Bartknecht (1981a).
Craven and Greig describe experimental work on the pressure generated by the detonation of ammonia nitrous oxide mixtures in 3 and 4 in. pipes initially at atmospheric...
