Date: Fri, 8 Feb 2008 07:41:00 -0500
Reply-To: Ralph Stuart <rstuart**At_Symbol_Here**UVM.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: Ralph Stuart <rstuart**At_Symbol_Here**UVM.EDU>
Subject: 16 Re: [DCHAS-L] Fume hood flow indicators
Comments: To: c2e2**At_Symbol_Here**

Based on the range of responses I received to yesterday's inquiry  
about fume hood flow indicators, it's clear that this is unsettled  
question (except where regulators have written specific technologies  
into code in specific jurisdictions).

I probably didn't make clear enough that our intent is to improve our  
fume training by simplifying our message. A campuswide retrofit of 400  
hoods is not in the cards. Our current training approach has been in  
place in various forms for at least 10 years and we aren't seeing any  
improvement in hood use practices (which is not to say that many UVM  
people don't use them well). We are seeing some serious problems,  
particularly in terms of poor hood practices and unnecessary energy  
use (these poor practices are often inspired by the alarm systems we  
do have in place).  As an article in C&EN recently suggested, I  
believe that laboratory workers are going to need to address the  
energy issue relative to hoods fairly soon as concerns over greenhouse  
gas emissions intensify.

One other caveat: I am talking in terms of "generic lab hoods" on our  
campus. I recognize that there are some chemical processes that  
require specific protective ventilation and such systems would not be  
included in the "fancy kimwipe" approach.

Anyway, thanks for everyone for their response and I'd be glad to hear  
more peoples' thoughts.

- Ralph

From: ACTSNYC**At_Symbol_Here**
Date: February 7, 2008 2:01:30 PM EST (CA)
Subject: Re: [DCHAS-L] Fume hood flow indicators

In the art and theater departments, I try to get them to buy a  
Velometer--the Alnor type that doesn't need batteries and can go a  
long time without calibration.  I teach them to use it and then they  
can really check their own air flow.



From: Dan Crowl 
Date: February 7, 2008 1:58:36 PM EST (CA)
Subject: Re: [DCHAS-L] Fume hood flow indicators

Hi Ralph,

We use the red ink manometer types - they cost a lost less than the  
electronic units and can't be disabled and don't send out alarms.

Dan Crowl
Michigan Tech

From: "Debbie M. Decker" 
Date: February 7, 2008 2:11:08 PM EST (CA)
Subject: Re: [DCHAS-L] Fume hood flow indicators


It is now a regulatory requirement that all fume hoods (no  
grandfathering) have a visual/audible alarm and that users are trained  
on what the alarms mean.  We've been installing monitors on our fume  
hoods, here, for about 10 years so compliance hasn't been too onerous.  
But it is taking time to get old hoods retrofitted.  About 250 to  
retrofit out of about 1600 hoods.

I agree with the requirement myself.  Though I have seen a pipette tip  
jammed into the "mute" button on the alarm to shut it up when the hood  
is operated incorrectly .


From: Georjean Adams 
Date: February 7, 2008 11:13:54 AM EST (CA)
To: Ralph Stuart 
Subject: Re: [DCHAS-L] Fume hood flow indicators

I'm interested in your thoughts:

I am on the ACS Board Committee for Environmental Improvement and am  
going to propose at our New Orleans meeting that  CEI sponsor a broad  
collaborative program of compiling and disseminating best practices,  
identifying technology development needs, educating all members of ACS  
plus schools and industry, maybe even tracking some metric to show  
improvement in correct use of fume hoods.

I assume DCHAS would be a major contributor to the effort.  Do you  
think it has potential?  Does the chemical enterprise need it?  Would  
it generate some energy in the ACS membership?  Would people in DCHAS  
be willing to actually work it?

Seems like such a concrete, cross-membership endeavor that could show  
some real short term benefits to safety and energy reduction and would  
be more rewarding than some of the high-falutin' policy statements CEI  
normally works on.

Not that I am an expert on hoods.  Far from it. (In fact, I'm a policy  
wonk who's never worked in a lab!) And I'm not positioned to directly  
manage a big program ( a lone, part-time consultant in chemical  
management issues who can't travel to meetings all over).


EHS Strategies, Inc.
- enabling organizations to meet their EHS vision


From: "Greene, Benjamin (WSTF-RF)[JTI]" 
Date: February 7, 2008 11:55:54 AM EST (CA)
Subject: RE: [DCHAS-L] Fume hood flow indicators

Hi Ralph - telltale flags on all hoods is a must, and depending on the  
geometry of the lab the use of hemispherical mirrors to be able to  
tell if the hoods are working when looking in through a window (if you  
have them).

I agree that the flow alarms may not be reliable and it is sometimes  
unclear what they are sensing (static pressure, flow, etc.).   
Ultimately you can end up with either silenced alarms or alarms that  
don't alarm when they are supposed to, not to mention alarms that go  
off when they aren't supposed to.  So to have a good alarm program you  
have to have the maintenance to go along with it.


From: "Hadden, Susan [PRDUS]" 
Date: February 7, 2008 1:03:25 PM EST (CA)
To: "Ralph Stuart" 
Subject: RE: [DCHAS-L] Fume hood flow indicators

It's really a behavior issue. Why would they pay attention to a  
telltale and not an alarm? At least the alarm is annoying enough to  
attract their attention. I would suggest installing the alarms and  
training the individuals as to what it means. Then put a sign next to  
the alarm that explains what it means (ie If the alarm is going off,  
the hood may not be protecting you). Or consider making it so that  
they can not turn off the alarm but must have Maintenance respond to  
reset it. That will really annoy them but will allow Maintenance to  
evaluate actual hood performance when resetting the alarm. Or, if  
possible, have a simultaneous alarm in the Maintenance monitoring area  
that indicates an alarm has gone off.

I work at a large pharma company and we have some folks who disable  
their alarms too. But we do quarterly lab inspections and check for  
that. We also try to continually educate as to how the hoods work and  
why a sufficient flow rate is needed to protect them.


From: "Harry J. Elston" 
Date: February 7, 2008 11:34:02 AM EST (CA)
To: Ralph Stuart 
Subject: Re: [DCHAS-L] Fume hood flow indicators


I think you're going to run into problems with NFPA 45 and ANSI Z9.5:

6-8.7.1: A flow monitor shall be installed on each new laboratory hood.
6-8.7.2: A flow monitor shall also be installed on existing laboratory  
hoods whenever any modifications or changes are made that can affect  
laboratory ventilation or the airflow through existing laboratories.

That's from the 1996 version, the only one here I have at the day job.

I don't have a copy of ANSI Z9.5 here with me at the day job, but I  
would wager that the most recent version has something to say about  

One of the hangups is "flow" - not d/p across the hood wall.  The only  
product that I've seen measure actual flow is am in-duct "Flow Cross"  
that Swiki Anderson uses.


Harry J. Elston, Ph.D., CIH
Midwest Chemical Safety, LLC

Editor, Chemical Health & Safety


From: "Haugen, Bob" 
Date: February 7, 2008 2:42:23 PM EST (CA)
Subject: RE: [DCHAS-L] Fume hood flow indicators


I respectfully disagree.

Of course, our company makes alarms as well as fume hoods, but "tell  
tales" are affected by humidity, and are difficult to calibrate.

If lab folks are having trouble understanding electric alarms, you  
might consider a safety seminar (or PowerPoint Video) explaining how  
to use the hoods and safety alarms.  Also, standardizing on a certain  
model campus-wide might help.


Dr. Bob Haugen


From: "Janet Baum" 
Date: February 7, 2008 11:45:40 AM EST (CA)
Subject: RE: [DCHAS-L] Fume hood flow indicators

Dear Ralph, As I understand this issue, it is a legal requirement in  
the "Right To Know" law that chemical fume hoods have electronic flow  
alarm system installed. Consult the General Counsel for your  
university before proceeding.

Further, it is also a matter of training and education of bench  
scientists/laboratory workers in the care and use of these devices  
instead of disabling the alarm system for their immediate convenience  
and gratification.

Your operating and/or engineering groups who maintain building  
ventilation systems should be engaged with the laboratory manager and  
EHS staff to investigate incidents of false-alarms, or fluctuations in  
flows that legitimately set off alarms.

Janet Baum, AIA
Health, Education + Research Associates, Inc.


From: Jennifer Minogue 
Date: February 7, 2008 11:02:06 AM EST (CA)
Subject: Re: [DCHAS-L] Fume hood flow indicators

The Ontario Fire Code requires alarms so we are stuck with them.   
However, I think most of them work OK.  We also have many fume hoods  
retrofitted with "Ventalerts" which get checked once per year and have  
a battery change at the same time.  These are on old hoods that didn't  
have alarms on them when installed.

I find the stack affect can fool the user into thinking the fume hood  
is operating when it is not.  Pilot lights can also fool you - burned  
out or, in one case, the light was on but the fire damper had shut due  
to corrosion so the fan was running but there was no draw.


Jennifer Minogue
Biosafety Officer
Environmental Health and Safety
University of Guelph
Guelph, Ontario N1G 2W1  Canada
Voice 519-824-4120-x53190
Fax  519-824-0364


From: "Laurence Doemeny" 
Date: February 7, 2008 12:26:18 PM EST (CA)
Subject: FW: [DCHAS-L] Fume hood flow indicators

Hi Ralph,

We had bubble gum lights and alarms outside each lab bank that would  
go off should the airflow fall below a preset level.  It was also  
connected to our Johnson controls facility management system.  The  
audio alarm could be switched off but the gumball lights kept running  
until maintenance reset them.  This system was useful during routine  
maintenance too, although during those occasions announcements were  
sent to all building occupants.  If you are interested, I can give you  
the name of the facilities engineer for you to contact.



From: "Peter Reinhardt" 
Date: February 7, 2008 4:48:47 PM EST (CA)
To: "'Ralph Stuart'" 
Subject: FW: [DCHAS-L] Fume hood flow indicators


Magnehelic gauges on all hoods! The users need to know what's  
happening with the latest technology. I wouldn't want to rely on a  
Kimwipe in court testimony.

With all due respect to your great wisdom, I think you are going  
backwards on your fume hood program. Hoods are the primary means of  
reducing lab exposures. They need to work properly, the users need to  
know how to determine that, and EHS needs to verify that. Users need  

There is NO TOXILOGICAL DATA for most chemicals used in labs. Many of  
these people will spend their lives working in a lab. Small chronic  
exposures is a huge risk to them.

Training, not Kimwipes!



From: "R Alton Simpson (asimpson)" 
Date: February 7, 2008 2:33:35 PM EST (CA)
To: Ralph Stuart 
Subject: FW: [DCHAS-L] Fume hood flow indicators

We have relatively good experience with the digital flow meters.  I  
would not want to go back to a more qualitative system.  We inform  
people about the system during in person training, and we have an on- 
line tutorial at


Alton Simpson, CHMM, NRCC-CHO
Director, Environmental Health and Safety
The University of Memphis
216 Browning Hall
Memphis, TN  38152-3340
(901) 678-4672   fax (901) 678-4673


From: "Rincon, Katherine" 
Date: February 7, 2008 11:25:25 AM EST (CA)
To: "Ralph Stuart" 
Subject: RE: [DCHAS-L] Fume hood flow indicators

Hello Mr. Stuart:

We have the same problem with the electronic flow alarms for our fume  
hoods as well; and using the Kimwipe doesn't give a flow rate.  We use  
the No. 480 Vaneometer Air Velocity Meter by Dwyer; the user spot  
checks the hood to verify the flow.  We placed them in every fume  
hood.  We start using them for the fume hoods that did not have any  
type of electronic alarm but then we started having problems with the  
ones that did due to calibration problems.  Also, the Fire Marshals  
wanted us to provide some kind of visual aid to indicate that the  
hoods were working. Every lab that has a fume hood gets a meter.  One  
meter is enough to check several hoods in the lab.  And of course, it  
is used only for spot checks by the hood user.  It costs around $25.00.

Best regards,

Katherine Rincon
Chemical Hygiene Manager
Environmental Health & Safety
University of Texas at El Paso
(915) 747-8135
(915) 747-8126 fax


From: "Robin M. Izzo" 
Date: February 7, 2008 1:51:36 PM EST (CA)
Subject: Re: [C2E2-L] Fume hood flow indicators


We require a magnehelic gauge or a digital flow readout, but without  
alarms.  Our experience is similar to yours - the students will find a  
way to silence them forever.

- Robin

Robin M. Izzo
Associate Director, EHS
Princeton University
609-258-6259 (office)

The purpose of life is to live it, to taste experience to the utmost, to
reach out eagerly and without fear for newer and richer experience.
-Eleanor Roosevelt


From: Stanley K Lengerich 
Date: February 7, 2008 4:58:31 PM EST (CA)
Subject: Re: [DCHAS-L] Fume hood flow indicators

Hi Ralph,

I read a lot of DCHAS messages, but this is the first one I've felt  
strongly compelled to respond to. I would highly discourage you from  
taking the route you have proposed regarding face velocity monitors.  
My concern would be that the qualitative telltale would be understood  
even less by the user, and it wouldn't have the necessary sensitivity  
to measure when flows have dropped out of a safe range. Also, I would  
think that it probably doesn't meet the spirit and intent of the OSHA  
(Federal) Lab Standard requirements for monitoring fume hoods.

It is true that too much information can confuse the fume hood user.  
We previously had a lot of monitors displaying the flow in feet per  
minute, and that created too much confusion for the user. For that  
reason we have been transitioning to monitors that use a safe/unsafe  
(green light/red light) indication, and the red light is accompanied  
by an audible alarm. The audible alarm is silenceable, but if the  
alarm condition is not satisfied within 10 minutes, it automatically  
reactivates (the red light always stays on during an alarm condition).  
We find that this strikes a reasonable balance of warning vs. nuisance  
so that the users don't try to defeat the audible alarm. The simpler,  
universally-recognized, green/red warning system is easy to understand  
and easy to train on, and it still provides the necessary measurement  

Best Regards,

Stan Lengerich, CIH
Engineering Consultant
Eli Lilly and Company
Indianapolis, IN 46285

Ralph Stuart, CIH
Environmental Safety Manager
University of Vermont
Environmental Safety Facility
667 Spear St. Burlington, VT  05405

fax: (802)656-5407

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