ETL 1110-3-498
24 Feb 99
filtered. Test sections can be provided with the filtration system to ease in-place leak testing of the
system, isolate which filter section fails the leak test, and for future leak testing of the filter system.
To test the carbon adsorbers, typically testing injection and sampling ports that are located before
and after the filter system will be adequate in testing a single stage adsorption system. To test two
stages of adsorption, a test section will be required between the stages. To test HEPA filters, test
sections will be required for sampling after the HEPA filter. Test ports must be placed at a
location where good mixing will occur or the test ports must be located approximately 10 duct
diameters before and after the filter system. The filter system will be quality assurance tested in
accordance with ASME N510 and MIL-PRF-32016(EA). Current commercial filtration systems
are of nuclear grade safety class design and are designed for use primarily by the nuclear industry.
The commercial filtration systems meet quality assurance requirements for nuclear facility
applications (ASME NQA-1) and generic seismic requirements in IEEE Standard 344.
Commercial filtration systems used for certain applications, primarily for containment, warrant the
use of ASME NQA-1 and IEEE 344.
(1) Filter Housing. The filter housing will be a bag-in and bag-out design conforming to the
applicable sections of ASME N509 and will be constructed of type 304 stainless steel. For
applications where contaminants will be continuously filtered, bags for the bag-in and bag-out
ports will be provided. For applications where contaminants will rarely be filtered, bags for the
bag-in and bag-out ports are not required.
(2) Roughing Filter. Continuously operated filter systems will have a roughing filter with
an average efficiency of 25 to 30 percent when tested in accordance with ASHRAE 52.1. The
roughing filter extends the life of the intermediate filter or prefilter and reduces its change
(3) Prefilter. The prefilter or intermediate filter will have an average efficiency of 80 to 85
percent when tested in accordance with ASHRAE 52.1. The prefilter extends the life of the HEPA
filter and reduces its change frequency.
(4) HEPA Filter. The HEPA filter frame and filter media will meet the construction,
material, testing, qualification, and documentation requirements of ASME N509, ASME N510,
and UL 586 and will have a filter efficiency of 99.97 percent at a 0.3 Fm diameter particle size
when tested in accordance with the MIL-STD-282 dioctyl phthalate (DOP) test method. The filter
frames will meet the requirements of ASME AG-1a, Section FC. The HEPA filter medium will
meet the requirements of MS MIL-F-51079D.
(5) Adsorption Filter. The adsorber charcoal media will be designed to adsorb aerosol with
a minimum residence time of 0.25 seconds and will meet the requirements of MIL-PRF-
32016(EA). Typically, for commercial filters, two stages are required to achieve the 0.25 second
residence time at airflow rates of 330 L/s (700 cfm) to 590 L/s (1,250 cfm). One stage of
filteradsorption can be used for airflow rates from 165 L/s (350 cfm) to 295 L/s (625 cfm). For
unknown threats and adsorption of volatile agents, ASZM-TEDA carbon conforming to EA-C-
E-3
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