PROBLEMS IN EXPERIMENTAL MEASUREMENTS OF DUST EXPLOSIONS

The experimental method employed for measuring the parameters of dust explosions was critically examined using methane/air as a model system . Because of the rapid rate that air enters the test vessel (in order to disperse the dust), the system is not at thermodynamic equilibrium which causes the actual concentration of air to be about 15% less than indicated by the measured pressure at the time of ignition, thus crea ting a significant error in the determination of explosion pressures. For measuring the lower explosible limit, the ignitor must be of optim um strength, otherwise too high or low limit values are obtained. Pyro technic ignitors, which are usually used for igniting dusts, produce a significant pressure by themselves; a method for accurately taking th is effect into account is given. Some unusual problems encountered wit h particular dusts are discussed.