Conduit seals are required at boundariesboundaries:
Boundaries may be formed by a barrier such as a wall of a tank or the wall, ceiling, or floor of a room. Alternatively, the boundary may be a boundary in space, defined by a distance from a vapor or gas source. Thus, a conduit passing from a Zone 0 area may extend into a Zone 1 area or an unclassified area, or, less likely, a Zone 2 area. of Zone 0 Zone 0: The only protection method permitted in these areas is intrinsic safety, so conduits are not necessarily required. , Zone 1, and Zone 2 areas. In each case, the seal must be within 10 ft. of the boundary. Zone 1 and Zone 2 seals are required to be made with fittings that are listed for the location listed for the location:
The seal may be part of another enclosure or fitting, but this rule requires the seals to be flameproof or explosionproof., are required to minimize passage of gas or vapor across the boundary, and must halt the passage of flame, so only explosionproof reducers are permitted between the seal and the boundary between the seal and the boundary:
The seal is permitted to be on either side of the boundary. Unnecessary fittings must be avoided to effectively limit flow of gas or vapor across the boundary..