You asked: Has anyone out there [here on this list ;~)] prohibited
horizontal sashes or have justifiable pros for having them?
Horizontal sashes, under certain situations, can offer operating cost
(energy) savings. They follow the same model as some of the newly
advertised 'Low Flow' fume hoods. The low flow fume hoods fall into two
categories, each offering lower energy costs: those that lower the face
velocity, and those that maintain the face velocity (at or near 100 FPM)
but limit the opening area. Horizontal sash fume hoods (or combination
sash) fall under the latter category, that is they can offer energy
savings by limiting the open face area of the hood when used in this
way.
Keep in mind that anyone reaching for operating cost savings by using
any volume reduction technology, such as variable-volume fume hoods or
either category of 'low flow' hood, must judge the situation carefully,
as the driver for exhaust volume for most labs with hoods is the air
change rate, which is a function of the lab volume and exhaust function
(hoods, canopies, snorkels) density. You can invest a great deal of
money in these technologies, only to find that you cannot lower the
exhaust volume (and save energy) because you would be breaching the
required air change rate (occupied or unoccupied) that has been
determined for the lab (or the cooling load, which may drive the low
exhaust volume limit).
Complicated, but it is a lab-to-lab judgement.
-----Original Message-----
From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU] On Behalf Of
Debbie Decker
Sent: Wednesday, May 31, 2006 7:18 PM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: Re: [DCHAS-L] Hood Sash question
Kerry:
I have successfully (mostly) banned horizontal sliding sashes in favor
of vertical rising sashes. I use the following reasons:
The researchers will never work with their arms around the horizontal
sash - they will shove the sash out of the way and work directly in
front of the diethyl death they have burbling away, with nothing between
them and their goop but air.
A vertical rising sash prevents researchers from diving head-first into
their hoods. With the sash at 18", they bonk their heads on the sash
and figure out a different way to work without climbing into the hood
.
The combo sashes are marketed as providing energy savings because they
limit the hood opening. The combo sashes are also more expensive. A
vertical rising sash, set at 18" with limits on lab airchange rate, a
variable air volume lab airflow control system and good sash management
(pull the thing down when not in use) can achieve similar levels of
energy savings. Since you're not located in California, you can take
advantage of energy savings using the lower flow fume hoods - 80 fpm or
so.
My project managers and design professionals have bought into the
vertical sashes and the researchers understand that the vertical sash
can protect them. I haven't had much resistance.
Hope this helps,
Debbie
------------------
Debbie M. Decker, Campus Chemical Hygiene Officer Environmental Health
and Safety University of California, Davis
1 Shields Ave.
Davis, CA 95616
(530)754-7964/(530)752-4527 (FAX)
dmdecker**At_Symbol_Here**ucdavis.edu
Co-Conspirator to Make the World A
Better Place -- Visit www.HeroicStories.com and join the conspiracy
-----Original Message----
From: "Kerry Smith"
Date: May 30, 2006 6:25:24 PM EDT (CA)
Subject: Hood Sash question
We are selecting hoods for several lab remodels. The architects have
already specified combination horizontal/vertical sashes. My experience
with hood users has given me a less than positive desire for horizontal
sashes. Has anyone out there [here on this list ;~)] prohibited
horizontal sashes or have justifiable pros for having them.
Thanks
Kerry J. Smith, CIH
Senior Industrial Hygienist
BYU Risk Management & Safety Dept.
T 801-422-2943
F 801-422-0711
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