DCHAS-L Archives Sep 29 2010 - Re: Need fume hood/fire alarm help

Dear Ken, There are two red-flags in your description today. First, air in large, or small, laboratories must be balanced. The overall amount of outside supply air must be slightly greater than the total exhaust air or some very bad problems will develop over time in your building if the building is under negative pressure relative to the outside atmosphere: 1) loss of mortar, if it is a masonry building, 2) deterioration of the exterior skin of the building to the extent that there will be widespread water leakage into the building which in turn deteriorates interior construction materials 3) break of vacuum seal in thermopane windows, then windows collect condensation and leak 4) deterioration of the roof membrane, where leaks will occur and no visable crack or split can be found 5) exterior doors very hard to open, perhaps exceeding ADA force limits 6) accelerated rates of air infiltration into the building bringing in measurable, troublesome amounts of mold, dirt, and other contaminants Need I list more? See my article in CHAS Journal titled "Old Lab Syndrome" for more Second, check to make sure that NFPA is actually the building code adopted by the authority having jurisdiction in your town. NFPA documents are not codes, but guidelines or standards. NFPA may not have any legal standing in your area. Find out what the current building code is and research that for what is required for your fire alarm system. Make sure you are referring to the correct code document(s). Good luck, Janet Baum, AIA and Fellow DCHAS On Wed, Sep 29, 2010 at 12:42 PM, Kim Auletta wrote: > We have recently renovated 2 floors of our 7 story Chemistry building. This > job included adding MANY more fume hoods than were already in the building. > 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 > course, 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 > quickly 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 mechanism that allows a person to overcome the severe > negative imbalance and safely 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 Proper door operation for egress shall be maintained when the supply > system shuts down and the lab exhaust system operates, creating a pressure > differential. > > Thanks! > > Kim Auletta > Lab Safety Specialist > EH&S Z=6200 > Stony Brook University > kauletta**At_Symbol_Here**notes.cc.sunysb.edu > 631-632-3032 > EH&S Web site: http://www.stonybrook.edu/ehs/lab/ > > Remember to wash your hands!

First, air in large, or small, laboratories must be balanced. =A0T he overall amount of outside supply air must be slightly greater than the t otal exhaust air or some very bad problems will develop over time in your b uilding if the building is under negative pressure relative to the outside atmosphere: =A0

1) loss of mortar, if it is a masonry building,=A0

2) deteriorati on of the exterior skin of the building to the extent that there will be wi despread water leakage into the building which in turn deteriorates interio r construction materials

3) break of vacuum seal in thermopane windows, then windows collect co ndensation and leak

4) deterioration of the roof membrane, where leaks will occur and no visable crack or split can be found

5) ex terior doors very hard to open, perhaps exceeding ADA force limits

6) accelerated rates of air infiltration into the building bringing in measurable, troublesome amounts of mold, dirt, and other contaminants

Need I list more? =A0See my article in CHAS Journal titled "Old Lab Syndrome" for more

Second, check to make sure that NFPA is actually the bu ilding code adopted by the authority having jurisdiction in your town. =A0N FPA documents are not codes, but guidelines or standards. NFPA may not have any legal standing in your area. =A0Find out what the current building cod e is and research that for what is required for your fire alarm system. Mak e sure you are referring to the correct code document(s).

Good luck,

Janet Baum, AIA and Fellow DCHAS
On Wed, Sep 29, 2010 at 12:42 PM, Kim Aule tta <k auletta**At_Symbol_Here**notes.cc.sunysb.edu> wrote:

We hav e recently renovated 2 floors of our 7 story Chemistry building. This job included adding MANY more fume hoods than were already in the building. 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 course, this now makes the buildin g so negative that they can't easily open the doors at the bottom of the stairwell/emergency exit and all the doors quickly slam shut. The consultan t 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 mechanism that allows a person to overcome the severe negative imbalance and safely exit? Any advice or examples are greatly appreciated.
NFPA 45, Sect. 8.10.4 Fire detecti on and alarm systems shall not be interlocked to automatically shut down chemi cal fume hood exhaust fans.
8.10.5 Proper door operation for e gress shall be maintained when the supply system shuts down and the lab exhaust system operates, creating a pressure differential.

Thanks!
Kim Auletta
Lab Safety Specialist
EH&S =A0 =A0Z=6200
Stony Brook University
kauletta**At_Symbol_Here** notes.cc.sunysb.edu
631-632-3032
EH&S Web site: http://www.stonybrook. edu/ehs/lab/
Remember to wash your hands!

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