Primary Considerations

DOE-HDBK-1092-98

5.4.1.3.1 PRIMARY CONSIDERATIONS

The following primary considerations should be used when selecting seals and drains:

1. Select the proper sealing fitting for the hazardous vapor involved (i.e., Class I Groups A, B,

C, or D).

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. NEC 501-5(c)(4) 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 1/

2 through 1 in. 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 1-1/4 through 6 in. have

extra-large work openings and separate filling holes so that fiber dams are easy to make. Overall

diameter of sizes 1-1/4 through 6 in. is scarcely greater than that of unions of corresponding sizes,

permitting close conduit spacings. Other style seals are for use with conduit running at any angle,

from vertical through horizontal.

5-27