From: Richard Belgrave <RBelgrave**At_Symbol_Here**CCNY.CUNY.EDU>
Subject: Re: [DCHAS-L] High performance hoods
Date: June 27, 2012 11:10:14 AM EDT
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: <1B4D1665F78352429F7714A6540EB03629429F34**At_Symbol_Here**>

HI Ralph;

All of the hoods in our main science building has been retrofitted to
improve performance at a lower CFM. The average face velocity was set to 80
CFM. All hoods were tested to the ASHRAE 110 standard. There is an effort
(in process) to go even lower as an energy saving measure. The additional
mechanics required presented greater opportunities for failure.

Performance was affected by other factors i.e. insufficient make up air.

Richard Belgrave
Director EHOS

-----Original Message-----
From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of
Ralph B Stuart
Sent: Wednesday, June 27, 2012 10:47 AM
Subject: Re: [DCHAS-L] High performance hoods

Does anyone have experience with such hoods and have they found them to
be acceptable for use with common solvents. Are there any downsides to their

I have seen demonstrations of them that indicate that they work as well as
more traditional hoods in terms of containment. Aerodynamically, there's
nothing particularly magic about 100 fpm, so I believe that a well designed
hood should be able to provide the same protection at 80 fpm and don't
forsee any operational downsides. Some jurisdictions have regulators who
need to be convinced of this, though.

Maybe someone with more direct experience of the lower flow hoods knows of
other challenges they present?

- Ralph

Ralph Stuart CIH
Laboratory Ventilation Specialist
Department of Environmental Health and Safety Cornell University


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