From: Eric Clark <erclark**At_Symbol_Here**>
Subject: FW: [DCHAS-L] [DCHAS-L] October Fume hood design workshop planning
Date: Tue, 16 Jun 2015 14:46:28 +0000
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: BY2PR09MB07385043A09A821D31AAC7A1EBA70**At_Symbol_Here**
In-Reply-To <28ED79E16AC69B45BD7C958C2126C2601560FC**At_Symbol_Here**DOWPOSTAL1.downey-inet.dow>

Hello Everybody,

I thought I’d pass this along to the group out there.  This is regarding the discussion from a few months ago on Fume Hood ON vs Fume Hood OFF during a fire.   

The local FD weighed in on this and provided the some insight.  See below.  


There’s also an NFPA parameter on this: 


In regards to the issue of the fume hood operation, there is a section in NFPA 45 – Standard on Fire Protection for Laboratories Using Chemicals.  Section 7.10.4 of NFPA 45 states that “fire detection and alarm systems shall not be interlocked to automatically shut down chemical fume hood exhaust fans.”





Eric Clark, MS, CHMM, CCHO

Safety Officer, Public Health Scientist III

Los Angeles County Public Health Laboratory



From: Lee Kirby [mailto:lkirby**At_Symbol_Here**]
Sent: Monday, June 15, 2015 4:16 PM
To: Sheena Chu
Cc: Eric Clark
Subject: RE: [DCHAS-L] October Fume hood design workshop planning


Hi guys…


Thanks.  Dr. Vernon from UC Riverside is right on.  You treat the fume hoods similar to cooking hoods in restaurants.  When a fire occurs in the cooking hood and activates the fire suppression system, the exhaust air remains on ventilating the smoke and heat and make-up (e.g. supply air) shuts-down as not to supply fresh air (e.g. oxygen) to the fire.  I test this operation all the time during these systems installations.  The pressure differential Dr. Vernon speaks of is directly out of NFPA 91 on Exhaust Systems.


I sent an email (cc both of you) to Mr. Ha on the matter.  I would also share this email from Dr. Vernon with Mr. Ha and others as it succinctly states the Code/NFPA requirements.


Thanks again.  Let me know if you require further assistance on this matter.


Best regards,


Lee Kirby

Hazardous Materials Specialist/Fire Inspector


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