From: Richard Palluzi <000006c59248530b-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU>
Subject: Re: [DCHAS-L] Hood shut down
Date: Mon, 30 Mar 2020 11:38:45 -0400
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Message-ID: 008701d606a9$4c8bac30$e5a30490$**At_Symbol_Here**verizon.net
In-Reply-To <9AEF2886-E5ED-4589-8448-5C8EF8C09EBC**At_Symbol_Here**keene.edu>


I agree that reducing the overall ACH is acceptable if you stay above 4 ACH
but the other problems will remain if you shut off the hoods. You could
remove any chemicals in the hood (eliminate the chance for vapors being
sucked out). You could seal up the hood exhaust by manually shutting off the
hood damper or sealing the hood face with plastic. But you need to think it
through carefully.

Richard Palluzi
PE, CSP

Pilot plant and laboratory consulting, safety, design,reviews, and training
www.linkedin.com/in/richardppalluzillc/

Richard P Palluzi LLC
72 Summit Drive
Basking Ridge, NJ 07920
rpalluzi**At_Symbol_Here**verizon.net
908-285-3782

-----Original Message-----
From: ACS Division of Chemical Health and Safety On
Behalf Of Stuart, Ralph
Sent: Monday, March 30, 2020 11:31 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] Hood shut down

> In the (unlikely) event you have 4 ACH with the hoods off then the ducts
will act as stacks and suck in air from the outside.

There are many class labs that are likely to have ACHs that are much higher
than 4, if there is more than one hood per 500 square feet of floor space. I
agree that turning hoods off entirely may not be appropriate, but if the
chemicals are not being used and appropriately stored, there are likely to
be opportunities to reduce air flow in many hood settings. We have reduced
our air flow in our hoods significantly in our two class labs.

- Ralph

Ralph Stuart, CIH, CCHO
Environmental Safety Manager
Keene State College
603 358-2859

ralph.stuart**At_Symbol_Here**keene.edu

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