Fire Screens for Filter Plenums

DOE-STD-1066-99

(30 to 45 percent atmospheric dust spot efficiency based on ASHRAE 52-

76) duct entrance filters.

14.6.1.2

High efficiency (at least 80 percent atmospheric dust spot efficiency based

on ASHRAE 52-76 test method) prefilters should be provided in the

ventilation system to protect the final HEPA filters from (1) particles with

diameters larger than 1 or 2 microns; (2) lint; and (3) dust concentrations

greater than 10 grains per 1,000 cubic feet (30 cubic meters). High

efficiency prefilters not only provide a degree of fire protection to the final

HEPA filters but can also extend the operational life of the HEPA filters.

14.6.1.3

Prefilters that should be located in final filter plenums enclosures should

be high efficiency prefilters (at least 80 percent ASHRAE atmospheric dust

spot efficiency). These prefilters should be located at least 36 inches (91

centimeters) upstream from the final HEPA filters.

14.6.1.4

Where airborne materials are known to be combustible (such as metal

powders), replaceable prefilters should be located as near the source as

possible. However, prefilters should not be located where there is an

unacceptable radioactive hazard to personnel in changing the prefilters.

14.6.2

Fire Screens for Filter Plenums

14.6.2.1

Fire screens should be located upstream from the prefilters and final filter

plenums.

14.6.2.2

Fire screens with metal meshes from 8 to 16 openings per inch should be

provided and located at least 4 to 5 feet (1.2 to 1.5 meters) upstream from

all prefilters and at least 20 feet (6.1 meters) upstream from all final filter

plenum enclosures.1

14.6.2.3

Where prefilters are located in final filter enclosures, fire screens should

be located at least 20 feet (6.1 meters) upstream from the prefilters.

Numerical data obtained from:

Lee, H.A., Final Report - Program for Fire Protection, Caves, Canyons, and Hot Cells, ARH-ST-104, Atlantic

Richfield Hanford Company, Richland, August 1974, pp. 59, 60.

Lee, H.A., Guide to Fire Protection in Caves, Canyons, and Hot Cells, ARH-3020, Atlantic Richfield Hanford

Company, Richland, July 1974, pp. 33, 35.

Burchsted, C.A., J.E. Kahn and A.B. Fuller. 1976. Nuclear Air Cleaning Handbook, ERDA 76-21. Oak Ridge

National Laboratory. Oak Ridge, Tennessee, pg. 227.

Hill, A.J., Fire Prevention and Protection in Hot Cells and Canyons, DP-1242, Savannah River Laboratory, Aiken,

South Carolina, April 1977, pg 12.