Minimum Potential of Charged Insulator to Cause Incendiary Discharges

Incendiary discharges can occur when a grounded metal sphere approaches a charged insulator, but there are few studies on its electrostatic potential causing ignition. The aim of this research is to determine the minimum potential required for ignition of flammable gases and vapors mixed with air. Discharges between a charged plastic film and grounded metal spheres are experimentally investigated, and an equation for estimating the discharge energy is presented. Then the minimum potential to produce the incendiary discharge is considered from this equation and compared with the experiments. It becomes clear that the minimum potential is determined by the diameter of the grounded metal sphere, the potential of the charged plastic film, and its apparent capacitance. The results obtained with hydrogen-air and propane-air mixture are reported.