Checking HEPA filters?

Austin Reade areade at
Fri Nov 1 10:55:43 EST 1996

We get our biohazard hoods checked annually by a local service company. 
If it's any use to you (assume you are in Maine) the company is Biotest Inc, 
Halifax, NS, Canada  ph 902-445-3034.  Bob MacLaren.  Bob might know of 
someone closer to you.

Filter integrity is checked by monitoring the penetration of dioctyl phthalate 
smoke.  The whole process including an air velocity scan of the filter/hood 
and fixing any minor leaks usually costs less than  $100 (Can.).  Maybe filter 
or hood manufacturers could give you a local contact, or try a nearby 
university microbiology or tissue culture department, or pharmaceutical 

How concerned are you about filter performance?  Are you looking for sterility 
or just a generally clean area for mycology?  A few pinpricks in a filter 
wouldn't likely compromise non-critical transfer work.  Of more concern to you 
might be how dirty the present filters are.  Although they become more 
efficient as they load up, eventually you need to replace them because the fan 
can't maintain adequate air flow.  You should be able to get some idea about 
this from the pressure drop across the filters.  The manual should give the 
normal working range.

My guess is replacing the filters would make the price you mention pale into 

In article <55bpkj$qqt at> Joe Harrington 
<joeharr at> writes:>From: Joe Harrington 
<joeharr at>>Subject: Checking HEPA filters?
>Date: 1 Nov 1996 03:09:07 GMT

>I'm looking into the possibility of purchasing a used clean station
>that was used in the medical industry. The unit is 6 ft wide, a 
>stainless steel cabinet with a formica work surface, and a variable 
>speed blower motor.

>I've not seen the unit yet, but I do have a picture of it. It apparently
>has a six filter array of of 24 x12" filters or perhaps (3) 24 x24 "
>filters. The pre-filter is below the work table, so I assume it is 
>bottom feed.

>I hope to check it out this weekend and the present owner, who is 
>not at all familiar with it, had it advertised for $475 or BO.

>Would anyone have any suggestions for determining the condition of 
>the HEPA filters?  A laser particle counter would be the way to 
>properly check this out, but I don't have an extra $2,000 to purchase
>one at this time,  :-)

>Any suggestions would be much appreciated.


>Mainely Mushrooms

----------------------------------- * ----------------------------------
Austin Reade, Microbiologist      Phone:    (902) 424-8670
Innovacorp                        Fax:      (902) 424-4679
101 Research Drive, PO Box 790    Internet: areade at
Dartmouth, NS, Canada  B2Y 3Z7

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