The short answer is, "No - never." Hoods are instruments that are designed with flow in mind. Adding permanent installations is akin to a chemist making permanent changes to the baffles, fan blade rate or blocking off room supply because he/she doesn't like the way it sounds/feels/whatever.

I don't say "no" often, but this is one time where I would absolutely put my foot down. (I MAY consider a qualified maybe if the user can prove to me that the hood will operate efficiently and provide the same level of protection to the user as if they shelf is not there. However, that takes a pretty hefty study.)

Harry

From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of Kennedy, Sheila
Sent: Saturday, May 12, 2018 1:13 PM

To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] Add a shelf in the fume hood

I'd really appreciate information from anyone who has placed such shelves for materials in continuous use. What materials? What height for ventilation? What else to consider?

Sheila Kennedy

Safety Coordinator

CHEM Teaching Labs

UC San Diego

---

From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> on behalf of Ellen M. Sweet <ems325**At_Symbol_Here**CORNELL.EDU>
Sent: Saturday, May 12, 2018 9:19:48 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] Add a shelf in the fume hood for H&E staining

Hi Zhen,

It is typical in Histology labs to keep the staining glassware/ troughs right in the hood. I=E2=80™ve seen a shelf placed in the back so that these can be raised in order to not block the baffle and also free up bench space in the hood for other work.

I would suggest asking how frequently they are used, however, because the dishes and jars with glass lids do not seal and the liquids will evaporate. If they are, essentially, in constant use, then they really aren't being left there endlessly. Cleaning everything up only to pull it all back out the next day would get annoying.

I hope this helps,

Ellen

Ellen Sweet

Laboratory Ventilation Specialist

Department of Environmental Health and Safety, Cornell University

American Chemical Society, Division of Chemical Health and Safety

315-730-8896

From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of Fu, Zhen
Sent: Friday, May 11, 2018 10:03 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON..EDU
Subject: [DCHAS-L] Add a shelf in the fume hood for H&E staining

Good morning,

We recently have a lab doing Hematoxylin and Eosin (H&E) staining contacted us to add a shelf in the fume hood to "store" the histology troughs (which includes ethanols at different concentrations, xylene, hemotoxylin, eosin).

The PI insisted this is a common procedure in histology labs and the solely purpose of this shelf is for this experiment.

From EHS and Fire code side, No chemical storage in fume hood (only notable exception being some toxic gases in lecture bottles). In code this applies to flammable liquids.

Any experience or comment can share with me regarding the best practice for this case. Thank you very much.

Best,

Zhen

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