Hi Richard,
Attenuation is still a factor with PTFE filters, starting near zero then increasing with dust loading. In HEPA-filtered environments dust loading and attenuation should be minimal however. Glass fiber filters are just the opposite. Attenuation is greatest with a new filter because of imbedding, then, as dust loading fills the 'pits', the attenuation decreases until the surface deposition is fairly uniform. The attenuation will then start to increase again from burial. Again, in HEPA-filtered air, the attenuation will stay higher much longer. David Baltz Bladewerx LLC 4529 Arrowhead Ridge Dr SE Rio Rancho, NM 87124 Ph: 505.892.5144 Fx: 505.890.8319 Email: <mailto:[email protected]> [email protected] URL: <http://www.bladewerx.com> http://www.bladewerx.com From: Treinen, Richard [mailto:[email protected]] Sent: Thursday, January 19, 2017 1:23 PM To: [email protected] Subject: [powernet] PTFE and Self-absorption Hi All, For those that have switched to PTFE/Teflon-based filters for air samples and lapel filters: We're now using Eichrom PTFE. What effect has it had on your self-absorption/attenuation/transmission factors for: 1. Air Samples? 2. Lapel Filters? In the 2013 EPRI alpha guideline they mention the PNNL study (PNNL-SA-62011) that recommends no self-absorption factor for PTFE/Teflon-based media. Thoughts? Thanks, Rick Rick Treinen Radiation Protection Engineer Pacific Gas & Electric Company Diablo Canyon Power Plant Bldg 104-2-216 Avila Beach, CA 93424 ------------------------ O: 805.545.6481 | C: 805.769.8001
