Checking HEPA filters?
joeharr at worldnet.att.net
Sun Nov 3 20:30:29 EST 1996
posted/mailedmicrobe at clark.pioneer.net (Steve Carpenter - Cascade
Research Assoc.) wrote:
>A dry-ice fogger to check for airflow distribution within any HEPA filter
>1. Purchase a 2' length of 4" diameter plastic pipe. I use ABS sewer
> pipe. Close off one end, being sure to use glue to make it watertight,
> and thread the other end so that you can place a screw-on cap on it.
>2. Fit the side of the pipe with a plastic or metal tapered pipe fitting
> over which you can place a 1/2-5/8" diam, 2-3' length of flexible, clear
>3. When you are ready to test, open the cap and put about a half quart to
> a quart of hot water. Throw in a good chunk of dry ice. Screw on the
>4. Presto! - out comes fog through the clear tubing in the side of the
> You can the use the fog in the chamber to see if the air is blowing
>properly. If you can access the plenum area above the filter, you may be
>able to see leaks through large holes, depending on conditions.
>I have use this apparatus to successfully test many HEPA units in cleanrooms.
>-Steve Carpenter, Ph.D.
> Cascade Research Associates
> & Abbey Lane Laboratory
> microbe at pioneer.net
Thanks for the informative responses regarding checking the filters.
I picked up the unit today in Mass. It was a bit BIGGER than I
anticipated, the filtered area was 72" by 32", and the entire cabinet
was custom made. I did some preliminary tests and it looks in very
good shape and I'll try out the other suggestions.
It was QUITE a challenge moving and we had to disassemble it
to get it down the basement step. But all in all, quite a deal for $450.
Thanks again to all respondents.
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