Deep-bed sand filter at Savannah River Laboratory

A deep-bed sand filter was placed in service during June 1974 at the Savannah River Laboratory. This filter provides a back-up for HEPA filters in the primary exhaust system. HEPA filters can fail due to deterioration, faulty seating mechanisms, fire, and/or pressure excursions. The deep bed filter area is 103 ft by 140 ft and consists of layers of rock, gravel, and sand to a depth of 7 ft 6 in. Design flow is 74,000 cfm at 5.15 linear fpm. Most of the pressure drop occurs in the 36-in. layer of the ''G'' sand (sieve size No. 50 to No. 30) where the submicron particulates are captured. The filter is described, and operating characteristics are summarized, including pressure drops and filter efficiencies as determined with DOP. (U.S.)