Date: Wed, 7 Oct 2009 21:16:55 -0400
Reply-To: Andrew Gross <gross.drew**At_Symbol_Here**GMAIL.COM>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: Andrew Gross <gross.drew**At_Symbol_Here**GMAIL.COM>
Subject: Re: Low-flow hoods
Comments: To: Jean & Ken Smith
In-Reply-To: <001801ca4610$50912130$4101a8c0**At_Symbol_Here**smithrocket>

on what ken stated.  check it through various times of day.  in my
lab, the warming of the building from the sun actually changes the air
flow.  I don't know if it affects our hoods but it can definitely be
seen on a high precision balance.

On Mon, Oct 5, 2009 at 7:05 PM, Jean & Ken Smith
> I don't know what the face velocity listed for your specific hoods, but b
> very careful of the placements of each of those hoods in relation to the
> ventilation system's air currents and drafts. =A0Even the best of the hoo
> will be negatively affected by air currents blowing into or across the fa
> of the hoods. =A0Low flow hoods are at higher risk of non-capture than th
> standard hoods.
> If the hood is in a very quiet air current area, the specs for that hood 
> be OK. =A0If even in the slightest doubt of the efficacy of the total int
> capture velocity at the hood face for whatever hood sash height is used, 
> smoke test should always be used in addition to the average velocity
> measured.
> It takes only a very small draft of air blowing across the face to reach 
> and negate one area of the open sash to reduce or negate the inflow veloc
> allowing for contents to escape. =A0I am speaking from experience where m
> hoods in our labs were badly placed and were negatively influenced by
> drafting air.
> Use a smoke test at the open face of the hood to determine the trajectory
> the air capture (or non-capture) across the opening of the sash to be saf
> Ken Smith
> CIH, Retired
> -----Original Message-----
> From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**] On Behalf Of
> Barbara Mowery
> Sent: Monday, October 05, 2009 1:42 PM
> To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
> Subject: [DCHAS-L] Low-flow hoods
> Dear Colleagues,
> I am doing the annual update of our Chemical Hygiene Plan, which specifie
> face velocity rates for fume hoods. However, our newly remodeled Organic 
> has energy-efficient, low-flow hoods. What is an appropriate value of fac
> velocity to specify for such hoods?
> Barbara Mowery
> General Chemistry Laboratory Coordinator
> Physical Sciences Department
> York College of Pennsylvania
> 441 Country Club Road
> York PA 17403-3651
> 717-815-6480
> Fax 717-849-1653
> This information is intended solely for the use of the individual to whom
> it is addressed. Any review, disclosure, copying, distribution or use of
> this e-mail communication by others is strictly prohibited. =A0If you are
> not the intended recipient, please notify us immediately by returning
> this message to the sender and delete all copies.

Previous post   |  Top of Page   |   Next post

The content of this page reflects the personal opinion(s) of the author(s) only, not the American Chemical Society, ILPI, Safety Emporium, or any other party. Use of any information on this page is at the reader's own risk. Unauthorized reproduction of these materials is prohibited. Send questions/comments about the archive to
The maintenance and hosting of the DCHAS-L archive is provided through the generous support of Safety Emporium.