Click here to make tpub.com your Home Page

Page Title: HEPA Filters
Back | Up

Click here for thousands of PDF manuals

Google


Web
www.tpub.com

Home

   
Information Categories
.... Administration
Advancement
Aerographer
Automotive
Aviation
Construction
Diving
Draftsman
Engineering
Electronics
Food and Cooking
Logistics
Math
Medical
Music
Nuclear Fundamentals
Photography
Religion
   
   

 



DOE-HDBK-3010-94
5.0 Surface Contamination; Summary
5.4
HEPA FILTERS
5.4.1
Thermal Stress
HEPA filters, both unused and removed from service due to high differential pressures (clogged), were
tested using solid particles at a range of temperatures less than required for failure. The efficiencies of
the filters prior to testing for 1.8 .m particles ranged from 99.97% to 99.9999989%. Two high flow
(2000 cfm) and one 1000 cfm HEPA filters with glass fiber media and various sealant and gasket
materials were tested. No releases were found at temperatures below 150oC (175oC for one of the high
flow filters). For the 1000 cfm type filter, the release rates for temperatures from 175oC and 190oC
started at 1E-6/min and reduced to 5E-8/min within 1 hour (the lower limit of detection was 2E-8/min).
The high flow HEPAs were tested to temperatures of 200oC and 250oC with release rates starting at 2E-
4/min and 2E-5/min and reducing to 3E-7/min in 30 min and 2E-8/min in 60 min. The decay in release
was exponential during the initial 30-minutes approaching the 60-min rate asymptotically. There was no
release of contamination from a oven-fired, mineral sealant, high flow type filter at temperatures up to
350oC and the release in other types of HEPA filters is associated with the emission of smoke (binder,
degradation of inert dust on filter, pyrolysis of gaskets). Thus, it appears that the heat-induced release
from 1000 cfm HEPA filter prior to failure may be as high as 1E-5. It is assumed that HEPA filters
destroyed by flame intrusion or by the impact of air at a temperature sufficiently high to melt the glass
fiber are subjected to high temperature air to result in the release given above for heat-induced release.
The RF is assumed to be 1.0 without an experimental basis. ARFs for high-flowrate HEPA filter may be
an order of magnitude higher (1E-4). On these bases, bounding ARF and RF values for the impact of
heat upon loaded HEPA filters are assessed to be 1E-4 and 1.0.
Page 5-30


Privacy Statement - Press Release - Copyright Information. - Contact Us

Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business