Subject: [DCHAS-L] Backup power for chemical fume hoods
Date: August 1, 2012 11:26:12 PM EDT
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: <5E76EF51D002544DAC5CFA68490FC5DA1194AB3C**At_Symbol_Here**>

I am seeking information on supplying backup power to fume hoods.


Our most recent buildings have generators and automatic transfer switches designed to power all exhaust fans for the duration of the outage.  Our control systems fail with exhausts dampers fully open.  Because the air handlers are not backed up, the building pressurization goes negative within minutes.


In a recently remodeled lab building, the negative pressure during an outage sucked in a window.  I have to presume doors were quite difficult to open and likely violated building code requirements..


One engineer recently told me that his designs will place only half the exhaust fans in emergency power, which he views as a good compromise.


Hoods in unoccupied labs are allowed to function at 60% face flow rates, which lends credence to the engineer’s rule of thumb.  I think we can safely assume that there will be no research operations in a building without ventilation or electrical power, so a lower level of exhaust seems reasonable.


Is there any authoritative source that addresses this situation?



Scott Goode, Professor

Department of Chemistry and Biochemistry

University of South Carolina

631 Sumter Street

Columbia SC 29208


Email:   Goode**At_Symbol_Here**

Phone: 803-777-2601

Fax:       803-777-9521


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