Date: Wed, 29 Sep 2010 12:16:15 -0700
Reply-To: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: scrooks**At_Symbol_Here**PPEPPRO.COM
Subject: Re: Need fume hood/fire alarm help

Life safety has to trump the standards you mention.  I can s peak directly to ANSI Z9.5 and that upcoming revision (which was written with an expectation that NFPA 45 is also addressing your situation in their next revision.) 
Z9.5 may not provide absolute clarity nor the answer th at you're looking for but it does attempt to fix the unintended earlier rec ipe for egress issues.  And although the update/publication is being held up while we address a seprate public objection, the section addressing your question will read as follows:
Within Section 5.2.3 Laboratory Ventilation - Emergency Modes
< /FONT>
Left-hand column "shall" text
FIRE =E2=80=93 Any manual or automatic mea ns of detecting fire (such as a pull station or smoke detector) in a labora tory room shall also activate an appropriate fire emergency mode of operati on for the room and/or building ventilation system.
< FONT face="Times New Roman">The selected fire emergency mode shall op erate all supply and exhaust equipment in the room in a manner that promote s egress, retards the spread of fire and smoke, and complies with applicabl e fire safety codes and standards.
Right-hand column "explanatory or should" text
The intent of t he fire emergency ventilation mode is to promote safe egress.  This means apply negative pressurization in the room of fire origin in order to retard the spread of smoke and toxic fire gases to other parts of the facility but do not pressurize to the ext ent that the force needed to open the door is excessive. (Also refer to the current versions of NFPA 92A and NFPA 45.)
The common prac tice of cutting off supply air to a fire zone does not apply to some labora tories.  The combination of a high exhaust rate and no supply can depressurize a room so far that some o ccupants would be unable to open the doors.  The initial design of the laboratory ventilation system mus t include analysis of flow rates, pressure levels and forces on the door to ensure that egress is possible.
< /FONT>

Steve Crooks, MS, CIH, CSP
Chair, AIHA/ANSI Z9.5-2xxxx
-------- Original Message --------
Subject: [DC HAS-L] Need fume hood/fire alarm help
From: Kim Auletta <kauletta**At_Symbol_Here**NOTES.CC.SUNYSB.EDU>
Date: Wed, September 29, 2010 1:42 pm
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU

We have recently renovated 2 floors of our 7 story Chemistry building. Thi s job included adding MANY more fume hoods than were already in the buildin g. The NFPA/ANSI/common sense code requires that the fume hoods stay & the supply air/HVAC system shuts off when the fire alarm is activated. Of c ourse, this now makes the building so negative that they can't easily open the doors at the bottom of the stairwell/emergency exit and all the doors q uickly slam shut. The consultant is at a loss of what to do to fix this.

How have your large buildings with numerous hoods dealt with this problem? Have you found a door mechani sm that allows a person to overcome the severe negative imbalance and safel y exit? Any advice or examples are greatly appreciated.

NFPA 45, Sect. 8.10.4 Fire detection and alarm systems shall not be interlocked to automatically shut down chemical fume hood exhaust fans.

8.10.5 Prope r door operation for egress shall be maintained when the supply system shut s down and the lab exhaust system operates, creating a pressure differentia l.


< FONT size=2 face=sans-serif>Kim Auletta
Lab Safety Specialist
EH& amp;S    Z=6200
Stony Brook University
631-632-3 032
EH&S Web site:
http://www.stonybrook .edu/ehs/lab/

Remember t o wash your hands!

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