Well...that depends on whose standards of efficacy you use (ASHRAE or ACGIH), what kind of processes are being done in the hoods, and if there are hoods near doors or other potential sources of cross drafts. I'm for jacking up the air supply rather than lowering the standard.
I'm an old person who remembers how ASHRAE lowered all the fresh air requirements for buildings and hoods in the 1970s. If you were around then, you know how badly that turned out. Then they did it again in the latest energy crisis.. So the lower rates are suspiciously familiar to me. I want my clients to use the ASHRAE-62-2001 standard plus some of the better distribution systems in the later standards.
A game-changing article was in the March ASHRAE Journal. It reported on a study in which tests demonstrated that people have a measurable reduction in mental performance at 600 ppm of CO2 which increases at 1000 ppm and further at higher levels. Yet ASHRAE-62 only requires systems that keep CO2 levels 700 ppm above outdoor CO2 levels which range from 300-500 ppm as a rule. So you can be at 1200 ppm CO2 and still have a compliant ASHRAE recirculating system. And let's just be honest, most schools' CO2 levels are even higher than this.
And the really ground-breaking thing about this study is it did not use fresh air as the control for CO2. The levels were spiked only with pure CO2. All the other usual variables were removed. We have always considered CO2 only as a marker for insufficient fresh air. Now it looks like CO2 may be directly related to health and mental acuity issues in buildings.
Monona Rossol, M.S., M.F.A., Industrial Hygienist
President: Arts, Crafts & Theater Safety, Inc.
Safety Officer: Local USA829, IATSE
181 Thompson St., #23
New York, NY 10012 212-777-0062
-----Original Message-----
From: Kim Gates <kim.gates**At_Symbol_Here**STONYBROOK.EDU>
To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Sent: Tue, Apr 30, 2013 7:43 am
Subject: Re: [DCHAS-L] Chemistry Fume Hood Experience
In our new undergrad chem labs, the hood low flow alarms kept going off also. The area has many hoods in a small space. The testing & balance company came in & found that there was not enough supply air. Increasing supply helped, but the alarms kept going off. I contacted the alarm manufacturer and found that the low flow alarm was set at 100 fpm - the point where the air flow was supposed to be set at. When students walked past the hoods (teaching lab=large number of people), the air flow movement caused the alarm to trigger. Resetting the alarm to go off at 70 fpm stopped the problem. The 70 fpm is still withing the hood efficiency range but allows for the air movement.
Have you checked your alarm set points?
Kim Gates
Laboratory Safety Specialist
Environmental Health & Safety
Stony Brook University
Stony Brook, NY 11794-6200
Kim.Gates**At_Symbol_Here**stonybrook.edu
631-632-3032
FAX: 631-632-9683
EH&S Web site: http://www.stonybrook.edu/ehs/lab/
Please note my name and email have changed.
On Mon, Apr 29, 2013 at 6:10 PM, Mary Ellen A Scott <mas35**At_Symbol_Here**case.edu> wrote:
We have performed the ASHRAE test on these hoods and they all passed. The alarms do go off frequently and so are ignored. So I am concerned about the wolf and have stated as much in writing. I have been asking for the monitors to be serviced. Starting with the monitors and followed with your suggestions may be enough to move through the block.
On Mon, Apr 29, 2013 at 4:57 PM, Yung Morgan <pmorgan**At_Symbol_Here**ehs.umass.edu> wrote:
For the new high efficiency hoods, require an Ashrae 110 test as manufactured(AM) and another one as installed (AI) for at least 10 or 20% of the hoods in your facility.
Air flow alarm visible( with numbers) and audible are a requirement. When testing the hoods we have a required that the hoods pass at flow rate: 80 FPM(70-90FPM) at 18 inches opening and hood alarm set at 55FPM , sash response time at 60 sec or less. Ask for a balancing report also to be sure the supply is proper for the space as a VAV hood will not work without enough supplied air, hence the constant flow alarm which can be a nuisance to the occupants. Fume hoods sensors are not always useful as research hoods have to run overnight at optimum flow rates, a constant battle between the energy group and safety people. Room occupancy sensors are fine as long as the researchers know to not to work in the dark(with the light off) unless they want their hoods air flow to go down.
Again, just my two cents.
Yung Morgan, MsPH
Laboratory Safety
Industrial Hygiene Services
Environmental Health and Safety
117 Draper hall
UMASS,Amherst MA 01003
phone (413) 545-2682
Fax (413) 545-2600
email : pmorgan**At_Symbol_Here**ehs.umass.edu
From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Jim Johnson
Subject: [DCHAS-L] Chemistry Fume Hood Experience
Good Afternoon,
I would like to start a discussion on current experience with chemistry fume hoods related to overall quality, best value, interior construction, coatings/materials of construction, installation issues, air flow alarms, order lead time, energy saving features plus anything else that comes to mind.
Thank you,
James S. Johnson Ph.D., CIH, QEP
JSJ and Associates
Pleasanton, CA 94588
--
Mary Ellen Scott, PhD.
Safety Specialist II
Case Western Reserve University
EHS - Environmental Health and Safety
Service Building 1st Floor Rm 113
2220 Circle Dr.
Cleveland, OH 44106-7227
216-368-6077
216-368-2236 (Fax)
maryellen.scott**At_Symbol_Here**case.edu
"There is no science without fancy and no art without fact" - Vladimir Nabokov
(1899-1977)