The safe gap: effect of explosion pressure

Flame-proof enclosure is one method of preventing accidental ignition of a flammable atmosphere by sparking in an electrical apparatus. Transmission of the explosion from inside the apparatus to the external atmosphere is prevented if the gap between plain parallel flange surfaces is less than the maximum experimental safe gap (MESG). In practice flange gaps permitted in electrical apparatus are less than the MESG to allow a factor of safety. The essential features of the safe gap and the MESG are reproduced and the effect of explosion pressure is looked at