Explosion-Proof vs. Purged or Pressurized Electrical Systems for Missile Hydrogen Areas

This paper describes and evaluates the two types of electrical equipment - purged or pressurized and explosion-proof - that may be considered for use in hydrogen hazardous areas, such as those at missile sites. Included is a discussion of the properties and potential hazards of hydrogen. There is also a brief description of intrinsically safe systems. The merits of pressurized and explosion-proof systems are compared in detail, and new developments are described. Finally, it is shown why new explosion-proof electrical equipment designed specifically for Class I, Group B, Division 1 (hydrogen) areas is the more feasible, from both technical and economic standpoints.