This document is based on NEC installation requirements for equipment installed in hazardous locations in the United States of
America.
Description
Conduit seals prevent explosions from spreading through conduit systems and igniting outside atmospheres. When properly installed
and filled with a UL-listed sealing compound, they prevent the passage of gases, vapors, or flames from spreading from a hazardous
location to a nonhazardous location.
The information describes the main purposes for seal fittings:
Restrict the passage of gases, vapors, or flames from one part of the conduit system to another area of the system.
Limit explosions to the sealed enclosure.
Prevent precompression, or “pressure piling,” in conduit systems.
WARNING: Failure to follow safety instructions may cause ignition of hazardous
atmosphere resulting in serious personal injury and/or property damage.
EXPLOSIONPROOF
SWITCH
IGNITABLE GASES OR VAPORS
IGNITED BY SPARK OF SWITCH
EXPLOSION CONFINED
WITHIN SEALED AREA
SF SEAL WITH DRAIN VALVE
SEALING CEMENT
POURING OPENING
FIBER DAM
Figure 1.
How Gases, Vapors, and
Flames Are Contained
INSTALLATION
Conduit Sealing Instructions for
Equipment in Hazardous Locations
1
Nipples (supplied with enclosure)
2
Sealing fittings (supplied with enclosure)
3
Explosionproof nipple
4
Explosionproof elbow
5
Explosionproof flexible conduit, for Class 2 wiring
6
Explosionproof flexible conduit, for Class 1 wiring
7
Explosionproof J-box, for connection of pan/tilt and
Class-1 camera; for ease of wire pulls, locate as close to
the pan/tilt as possible
8
Sealing fitting, for separation of hazardous and
nonhazardous locations
