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Published: 1978

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Initial results from a program to determine response of 610- x 610-mm (24- x 24-in.) HEPA filters to tornado-induced pressure transients are described. Filters were structurally tested by subjecting them to 20.7-kPa (3-psi) pressure differentials at pressurization rates from 6.9 kPa/s (1 psi/s) to 34.5 kPa/s (5 psi/s). Two sizes of filters were used in the tests: 149 mm (57/ in.) thick and 292 mm (111/2 in.) thick. The 149-mm (57/ in.- ) thick filters failed catastrophically at 20.7-kPa (3-psi) pressure differentials. Pressure drop across the filters, not pressurization rate, appears to be the primary cause of failure. The 292-mm- (111/2-in.) thick filters were also tested with the above pressurization rates. These units failed by breakage of the folded downstream ends of the fiber mat. Of four 292-mm- (111/2-in.- ) thick filters tested, a 20.7-kPa (3-psi) pressure differential produced failure at the lowest and highest pressurization rates, but not at two intermediate rates. Additional tests will be required to determine a possible relationship between structural failure and pressurization rate. Flow-resistance data were also obtained for the 610- x 610-mm (24- x 24-in.) filters. Other activities described concern construction of small-scale particulate-loading and pressure-testing devices. These devices will be used to test 203- x 203-mm (8- x 8-in.) filters so that methods of testing and instrumentation requirements can be established for the full-scale tests. Progress is also reported on the data acquisition systems, the laser instrumentation system, and the construction of a building over the facility test section.