Dust explosion venting of small vessels and flameless venting

Dust explosion venting is an established method of protecting against damaging explosion over-pressures, and guidance is available for many industrial situations. However, there is a need to: (a) establish the venting requirements of small vessels and whether current guidance and predictions in BS EN 14491:2006 need revising, and (b) improve understanding of the potential and limitations of flameless venting. This paper describes initial results from an ongoing programme of research.Small vessel tests are carried out using cornflour and wood dust on: a commercial sieve unit, a commercial cyclone, and a 0.5 m3 test vessel with explosion-relief openings without vent covers. Initial 0.5 m3 vessel tests give reduced explosion pressures that are lower than those predicted. This is because the predicted pressures are based on openings with vent covers. The reduced explosion pressures measured in the sieve unit and the cyclone are also less than predicted: the reasons are discussed.Flameless vesting tests are carried out using cornflour and wheat flour on a commercial flame arrestor unit. Initial tests demonstrate benefits, particularly a high level of flame extinguishment, but a problem of reduced venting efficiency compared to conventional venting.These initial results indicate that further research is needed.