The Bureau of Mines researched a system for the rapid grab sampling of heterogeneous mixtures of gases and dusts during the preignition and postignition stages of dust explosions. The combustion chamber in which the explosion occurs is first fitted with a hypodermic sampling needle with its inlet end at the desired sampling point within the chamber and its sharp, injecting end protruding outside of the chamber. Rapid sampling (approximately 25 to 50 ms) is achieved with a double-acting, air-pressure-actuated cylinder. The forward stroke of the cylinder thrusts the rubber septum seal of an evaculated glass sampling tube onto the protruding needle, which punctures the septum, filling the tube with gas and dust from the combustion chamber. The return stroke of the cyclinder reseals the sampling tube by returning the mechanism to its original position. The initial time of sampling and the duration of sampling are independently variable and controlled by a microprocessor. Results obtained with a trimodal distribution of coal dust show no significant size discrimination at least up to 70 um.