I really, really dislike swing vane anemometers for even spot checking fume hood face velocity. They are a nice, small, all-in-one box, but that very fact requires you to obscure a good deal of the face in order to position and read the thing. And the units I’ve had access to had the meter portion on the side so you almost had to put your head inside the hood to read it. (that is an exaggeration, but not by much.)
Peter Zavon, CIH
Penfield, NY
PZAVON**At_Symbol_Here**Rochester.rr.com
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> On Behalf Of James Saccardo
Sent: Wednesday, January 10, 2024 2:02 PM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: Re: [DCHAS-L] Fume hood shutdown = recertification?
Get yourself a little swinging vane velometer so that you can do a spot check between annual certifications.
Sometime in Universities there are breaks and fume hoods are not used and switched off to save energy and mechanical equipment.
The question is, are there different settings for HVAC supply air when the fume hood is one, and when it is off – If the same, you may experience increased pressure differentials at entrances and windows when the hood is running.
I would be better to know if the hood is tied to the supply air or not (i.e. supply air volume is increased when the hood it activated) unless it’s a naturally ventilated building, in which case the point is moot.
James
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It is a gray area. Certainly the safest and most defensible approach would be to retest the hood because something might have changed. In my experience the hood is likely to work exactly the same (plus/minus) after being turned on again if – as you say – nothing changed. My major concern would be why was it turned off for so long yet nothing changed. I would be very worried that something, somewhere in the system would have changed and so affect the performance. SO I thing retesting to certify to would be prudent but not mandatory.
Richard Palluzi
PE, CSP
Pilot plant and laboratory consulting, safety, design,reviews, and training
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Good afternoon,
If a fume hood is 'turned off' for an extended period of time (say, 6-12 weeks) but was certified as meeting manufacturer specs for face velocity by a testing company, is it best practice/optional or required to have it recertified when it becomes operational again, assuming there are no changes (such as a fan replacement) and is within 12 months of certification? This is a continuous volume HVAC system, not integrated into a building management system...
I realize there may be concerns about backdraft, maintaining appropriate ACH in the space, etc, which we'll have to investigate but I wanted to check specifically whether institutions would recertify. (And I agree face velocity is just one measure of ability to capture fumes/vapors/mists).
Margaret
--
Margaret A. Rakas, PhD.
Lab Safety & Compliance Director
Clark Science Center
Smith College
413-585-3877 (p)
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