Date: Wed, 12 Jul 2006 13:46:45 -0400
Reply-To: Ralph Stuart <rstuart**At_Symbol_Here**>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: Ralph Stuart <rstuart**At_Symbol_Here**>
Subject: 11 Re: Fume Hood Sashes

A collection of the off-line responses I've received in response to  
my inquiry yesterday (which should have been entitled "Fume Hood  
Sills" rather than "Fume Hood Sashes"). I agree with those who  
suggest it is a lab design as well as a user training issue.  
Unfortunately, it's hard to apply 21st century design practice to a  
1970 building (which had several budget cuts during the design phase  
without a corresponding decrease in square footage)...

Thanks to everyone who responded.

- Ralph

From: "Hadden, Susan [PRDUS]" 
Date: July 11, 2006 5:11:39 PM EDT
Subject: RE: [DCHAS-L] Fume hood sashes

I work at a large pharma R&D site. I was a Discovery chemist for many  
years before joining the Safety department. In my experience, most  
chemists do not understand how their fume hoods work. (I know I did  
not.) A couple of articles in JCHAS about computational fluid  
dynamics a few years ago were very helpful to me and I have shared  
them with those chemists of ours who expressed interest. So, I think  
ignorance is the biggest reason coupled with wanting to the "get the  
job done" attitude.


From: Pat Ceas 
Date: July 11, 2006 5:14:13 PM EDT
Subject: Re: [DCHAS-L] Fume hood sashes

It is pure ignorance.  They can not remove the air foils!!  It is an  
integral part of the hood, and a serious safety issue since it will  
affect containment.

Pat Ceas

Chemical Hygiene Officer
St. Olaf College
Northfield, MN 55057


Date: July 11, 2006 5:25:49 PM EDT
Subject: FW: [DCHAS-L] Fume hood sashes

I think this situation would be a good opportunity to do some  
research: I would be interested in seeing the results of an ASHRAE  
110 test (including tracer gas) on some of these hoods with and again  
without the airfoils.  I suspect that the hoods that pass with the  
airfoils in place might not pass with the airfoils removed.  It would  
also be instructive to look at smoke introduced into the hoods; I  
suspect the turbulence will be visible without the airfoil.

I think the removal of the airfoils shows ignorance on the part of  
the users.  We include a good bit of information on hoods as part of  
our lab safety seminar, and our lab safety specialist discusses (and  
demonstrates) hood problems when she tests the hoods and does audits.  
Our people tend to strap cylinders beside the hoods.  This means that  
the airfoils stay in place, the cylinders do not obstruct air flow  
into the hoods, and people have more room to work safely in the  
hoods.  We don't have a lot of unauthorized modifications to hoods by  
lab personnel.


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: "matt" 
Date: July 11, 2006 6:00:21 PM EDT
Subject: RE: [DCHAS-L] Fume hood sashes

The laboratory fume hood is a piece of safety equipment.  Users need  
to be trained in the correct use, maintenance, and testing of this  
equipment just like any other type of safety equipment.   
Modifications of any safety equipment by users to suit their  
convenience must never be allowed since these compromise the  
protective factors of the safety equipment.  A quick trip through the  
Fischer safety catalogue should identify suitable cylinder stands and  
a few feet of flexible 1/8" stainless tubing will allow the lines to  
fit under the airfoil.

Matt Schneider

From: John Nail 
Date: July 11, 2006 9:29:07 PM EDT
Subject: Re: [DCHAS-L] Fume hood sashes

Ignorance on the part of the user. He/She needs to use a gas in the  
hood and seeks the most convenient way of attaching the cylinder clamp.

On new lab and lab remodels, it would be a good idea to design in a  
way to attach one or two tank clamps without removing the front air  

At least be thankful that the occupants are securing the tanks! I  
found two unsecured He tanks in a reception room a few weeks ago.


John Nail
Associate Professor and Department Chair
Chemistry Department
Oklahoma City University

From: "Peter Zavon" 
Date: July 11, 2006 10:24:33 PM EDT
Subject: RE: [DCHAS-L] Fume hood sashes

I would put it down to ignorance.  Attaching a cylinder in front of a  
hood is like having a second person standing there all the time.  It  
will have a severely adverse impact on the air flow patterns into the  

In years gone by, the incidence of foil removal was not nearly so  
great.  So I suspect something else has changed.

Peter Zavon, CIH
Penfield, NY


From: Joe Passante 
Date: July 12, 2006 9:23:16 AM EDT
Subject: Re: [DCHAS-L] Fume hood sashes

Our new construction at Penn includes locations in the lab where  
cylinders can be secured and connected to copper tubing which feeds  
an inert specialty gas valve on the hood.  That coupled with a vacuum  
pump cabinet frees up a lot of space in front of the hood.

Modifying fume hoods is not a great idea.  Air foils smooth out  
turbulent flow  or back flow out of the hood.

Joseph R Passante, CIH, CHO Industrial Hygiene Manager Environmental
Health & Radiation Safety University of Pennsylvania 215.746-6550
215-898-0140 (F) 215-651-0554 (M)

From: Jennifer Minogue 
Date: July 12, 2006 10:05:42 AM EDT
Subject: Re: [DCHAS-L] Fume hood sashes

Re removal of air foils

1.  Ignorance of the users tops the lists.  Most wouldn't know what  
an airfoil is much less what it does.

2.  Bad lab design - no place to put the cylinders next to the fume  
hood.  This really bugs me because they end up in the aisle space.  
Why not make an alcove?  Why this feeling that every piece of wall  
space needs a bench, cupboards, or desk.  This is why garbage cans  
end up as tripping hazards - no one made space for them when the labs  
were designed.


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: "Michael Kleinman" 
Date: July 12, 2006 12:44:04 PM EDT
Subject: RE: [DCHAS-L] Fume hood sashes

Aren't most fume hoods operated with the sash open such that the flow  
is regulated to a nominal flow depending on the type of use?

Also it is required (at least in CA) to chain cylinders at the top  
and the bottom.

Mike Kleinman


From: "William  Parks" 
Date: July 11, 2006 6:07:51 PM EDT
Subject: Fume Hood Sashes

Possibly just ignorance..........and yet..........................the  
sashes were not posted do not use????? The lab supervisor  
notified???? A written report made to the CHO??????

I did all three.......and the success rate was 100%. As a staff  
industrial hygienist, once was all it took.

Bill Parks

From: "Victor Neuman" 
Date: July 12, 2006 1:52:55 AM EDT
To: rstuart**At_Symbol_Here**UVM.EDU, DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: RE: Fume hood sashes

Except for those few fume hoods which are designed to operate without  
an airfoil, 80%+ of fume hoods work really badly with their airfoil  
removed.  After testing hundreds of fume hoods both ways, removing  
the airfoil is a good way to make your fume hood leak.

Best Regards,

Victor Neuman
Professional Engineer

Cell: (619) 865-8235

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