The inflammability in suspension of mixtures of combustible and incombustible dusts

An account is given or a new laboratory method of determining the least proportion of incombustible dust which must be added to a combustible dust in order that the mixture, when dispersed in any volume of air will not propagate flame. In common with other small-scale methods depending on the propagation of flame in cold dust/air suspensions, the method seems to give low results as compared with large-scale gallery tests. It appears to be suitable for comparative measurements, however, and has been used to study the effect of the character and fineness of the incombustible dust on its ability to suppress flame in flour or cork dust/air suspensions. The relative inflammability of a number of combustible dusts has been assessed in terms of the addition of a standard limestone dust required to achieve flame suppression in each case.