Section FC of the ASME AG-1 Code addresses glass fiber HEPA filters and restricts the media velocity to a maximum of 2.54 cm/s (5 ft/min). Advances in filter media technology allow glass fiber HEPA filters to function at significantly higher velocities and still achieve HEPA performance. However, diffusional capture of particles < 100 nm is reduced at higher media velocities due to shorter residence times within the media matrix. Therefore, it is unlikely that higher media velocities for HEPA filters will be allowed without data to demonstrate the effect of media velocity on removal of particles in the smaller size classes. In order to address this issue, static testing has been conducted to generate performance related data and a range of dynamic testing has provided data regarding filter lifetimes, loading characteristics, changes in filter efficiency and the most penetrating particle size over time. Testing was conducted using 31 cm × 31 cm × 29 cm deep pleat HEPA filters supplied from two manufacturers. Testing was conducted at media velocities ranging from 2.0–4.5 cm/s with a solid aerosol challenge composed of potassium chloride. Two set of media velocity data were obtained for each filter type. In one set of evaluations, the maximum aerosol challenge particle size was limited to 3 μm, while particles above 3 μm were not constrained in the second set. This provided for considerable variability in the challenge mass mean diameter and overall mass loading rate. Results of this testing will be provided to the ASME AG-1 FC Committee for consideration in future versions of the HEPA standard. In general, the initial filter efficiency decreased with increasing media velocity. However, initial filter efficiencies were generally good in all cases. Filter efficiency values averaged over the first ten minute of the loading cycle ranged from 99.970 to 99.996%. Additionally, the most penetrating particle size was observed to decrease with increasing media velocity, with initial values ranging from 194 to 134 nm.
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The 11th International Conference on Environmental Remediation and Radioactive Waste Management
September 2–6, 2007
Bruges, Belgium
Conference Sponsors:
- Nuclear Division and Environmental Engineering Division
ISBN:
978-0-7918-4339-0
PROCEEDINGS PAPER
Evaluation of the Effects of Media Velocity on HEPA Filter Performance
Steven Alderman,
Steven Alderman
Mississippi State University, Starkville, MS
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Michael Parsons,
Michael Parsons
Mississippi State University, Starkville, MS
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Kristina Hogancamp,
Kristina Hogancamp
Mississippi State University, Starkville, MS
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O. Perry Norton,
O. Perry Norton
Mississippi State University, Starkville, MS
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Charles Waggoner
Charles Waggoner
Mississippi State University, Starkville, MS
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Steven Alderman
Mississippi State University, Starkville, MS
Michael Parsons
Mississippi State University, Starkville, MS
Kristina Hogancamp
Mississippi State University, Starkville, MS
O. Perry Norton
Mississippi State University, Starkville, MS
Charles Waggoner
Mississippi State University, Starkville, MS
Paper No:
ICEM2007-7075, pp. 599-603; 5 pages
Published Online:
May 29, 2009
Citation
Alderman, S, Parsons, M, Hogancamp, K, Norton, OP, & Waggoner, C. "Evaluation of the Effects of Media Velocity on HEPA Filter Performance." Proceedings of the The 11th International Conference on Environmental Remediation and Radioactive Waste Management. 11th International Conference on Environmental Remediation and Radioactive Waste Management, Parts A and B. Bruges, Belgium. September 2–6, 2007. pp. 599-603. ASME. https://doi.org/10.1115/ICEM2007-7075
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