Suppression of dust explosions by means of different explosive charges

Abstract

The research was aimed at the development and testing of a super fast explosion suppression system using different explosive charges. The experiments were carried out on a prototype device (steel container) of 2 l capacity, closed by means of a membrane. Below the membrane, there was an exhaust connector pipe, at the end of which was a dispersing head. About 1 kg of extinguishing material was located inside the container. The membrane was ruptured by the explosion of a miniature cumulative charge placed on the membrane surface inside the container. In some experiments the explosive charge was located both on the membrane surface and in the upper part of the container—over the extinguishing material. Pentryt, pyrotechnic charge and powder charge were used as the explosive material. In the first case, the container was filled up (above the extinguishing material surface) with nitrogen under pressure in the range of 30–50 bar. In two other cases, there was no overpressure inside the container. The pyrotechnic charge and powder charge were used as gas generators in order to produce the overpressure only after triggering the system by the signal from the protected volume. Standard electric igniters were applied to initiate the explosive material. The main reason for using the explosive materials for membrane perforation was their high combustion velocity, that enabled opening of the membrane within several microseconds. The dust explosion suppression occurred as a result of the activity of extinguishing material blown out of the container by means of compressed gases. The suppressing powders were used as the extinguishing material. The results of the research into optimization of the shape and miniaturization of the explosive charge mass are presented. Also, the process of shaping of the exhaust stream of the extinguishing material was recorded. Finally, the dust explosion suppression process in a 1.25 m3 chamber, using the developed super fast extinguishing system was studied.