Anyone who has worked in a refinery would have seen a safety demonstration of a high static charge set up in petroleum liquid just by pumping into a container.Fuel sold has a static dispersant added to eliminate static buildup.....The static charge needs to reach a certain energy level before it will ignite vapors or gases or dusts.Some very low,like acetylene oxygen mixes,some quite high hydrocarbon air mixes.Blackpowder will have a certain energy threshhold,a spark with higher energy will ignite.....And according to Davis,blackpowder does ignite by a blow,and gives tables of tests of explosive initiation energies."Chemistry of Powder and Explosives " T Davis.