Types of Sealing Fittings

DOE-HDBK-1092-2004

2. Select a sealing fitting for the proper use in respect to mounting position. This is particularly

critical when the conduit runs between hazardous and nonhazardous areas. Improper

positioning of a seal may permit hazardous gases or vapors to enter the system beyond the

seal and to escape into another portion of the hazardous area or into a nonhazardous area.

Some seals are designed to be mounted in any position; others are restricted to horizontal

or vertical mounting.

3. Install the seals on the proper side of the partition or wall as recommended by the

manufacturer.

4. Only trained personnel should install seals in strict compliance with the instruction sheets

furnished with the seals and sealing compound. Precautionary notes should be included on

installation diagrams to stress the importance of following manufacturer's instruction.

5. The NEC prohibits splices or taps in sealing fittings.

6. Sealing fittings are listed by UL for use in Class I hazardous locations with sealing

compound only. This compound, when properly mixed and poured, hardens into a dense,

strong mass, which is insoluble in water, is not attacked by chemicals, and is not softened

by heat. It will withstand with ample safety factor the pressure of exploding trapped gases or

vapor.

7. Conductors sealed in the compound may be approved thermoplastic or rubber insulated

type. Both may or may not be lead covered (the lead need not be removed).

Caution: Sealing compounds are not insulating compounds; therefore, they shall not be used as

such.

5.4.1.3.2

TYPES OF SEALING FITTINGS

Sealing fittings meet the requirements of NEC when properly installed.

A certain style of sealing fittings are for use with vertical or nearly vertical conduit in sizes from

inch through 1 inch. Other styles are available in sizes 1/2 through 6 in. for use in vertical or

horizontal conduits. In horizontal runs, these are limited to face up openings. Sizes from 1

through 6 inches have extra-large work openings and separate filling holes so that fiber dams

are easy to make. Overall diameter of sizes 1 through 6 inches is scarcely greater than that of

unions of corresponding sizes, permitting close conduit spacing. Other style seals are for use

with conduit running at any angle, from vertical through horizontal.

5.5

MANUFACTURERS' DIGEST

Manufacturers produce NEC code digests for selection of seals and drains and provide, by

class and division, catalog data and installation diagrams for their use in electrical power and

lighting systems in hazardous areas. The manufacturers' NEC code digests should be in

compliance with current NFPA/NEC requirements. The two that are most used are as follows:

1. Crouse-Hinds ECM Code Digest

2. Appleton's NEC Code Review.

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