From: Dr Bob <drbob**At_Symbol_Here**FLOWSCIENCES.COM>
Subject: Re: [DCHAS-L] Repurpose Perchloric Acid Hood
Date: Wed, 10 Feb 2021 18:37:22 +0000
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID: BN8PR07MB634089F43C303A83FECE03D7D98D9**At_Symbol_Here**

Hi All!


I agree with Harry that HCl will kill a perchloric hood if used in large quantities.


For a lot of reasons, I would never repurpose such a hood!


See link below from the Flow Sciences web page:


There's also video post of hood and its performance on the FSI linkedin site:


Dr. Bob Haugen

Director of Product and Technology Development

Flow Sciences, Inc.


910 332 4878
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From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> On Behalf Of Harry J. Elston
Sent: Wednesday, February 10, 2021 12:21 PM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: Re: [DCHAS-L] Repurpose Perchloric Acid Hood




Just because you can do something, doesn't mean you should.  Perchloric acid hoods are typical stainless steel and nozzles for the washdown system are typically brass or bronze (though I've seen some plastic ones in newer systems).  Converting the hood to "general use" typically involves using hydrochloric acid, which will chew up the stainless steel and bronze/brass nozzles pretty quickly.  Hot acid vapors will also chew up any brass/bronze in the hood.   (Also know that hot acid vapors will chew up galvanized ductwork and metal fan blades too.)


If you can restrict the hood to non-acid use, you can get the ductwork cleaned out and use it.  


Standard warnings and cautions apply with respect to perchlorates in the hood when performing maintenance or conversion.




On Wed, Feb 10, 2021 at 11:02 AM Stephen Beaton <Steve.Beaton**At_Symbol_Here**> wrote:

Hello all, 


Can a perchloric acid hood be repurposed as a standard fume hood for typical chemistry reactions? Are there any limitations?


There are some older perchloric acid hoods, but the wash down cycle is no longer functional (perchlorates have been addressed). There is no anticipated work with perchloric acid. The exhaust fan is still operational, and can draw an appropriate face velocity.



Thank you.


Stephen Beaton, MSc, CHO, CRSP
Chemical Safety Manager

Environmental Health and Safety Office
902.494.1934 | steve.beaton**At_Symbol_Here**
Dalhousie University



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Harry J. Elston, Ph.D., CIH, PMP

Principal, Midwest Chemical Safety, LLC


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