From: Jeffrey Lewin <jclewin**At_Symbol_Here**MTU.EDU>
Subject: Re: [DCHAS-L] Fume hood article of interest
Date: Tue, 31 Aug 2021 16:55:50 -0400
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID: CAEwQnqi=MZm9f1HR8W++oCseVtEpHZnF5wmnEsydcb6m9WRUSQ**At_Symbol_Here**

The real challenge is making sure users understand the system in the lab they are working in, especially if they work in multiple spaces.

Our Chemistry building (50+ years old) has different hood operations depending on the lab
- Scheduled operations; off nights and weekends. Better suited for teaching labs (But do they have night labs? Does the schedule adjust for them?). Challenges include hoods that might have unattended operations (especially in labs that have been converted into research labs), weekend prep for courses, etc. In general the schedule can be overridden by calling the Central Heating Plant (CHP) but does the user understand this?
- Scheduled operations with local override. In many of the labs there is a switch that goes between "automatic" and "hand." Hand = manual which isn't necessarily intuitive to many people (I've had people tell me that they thought "automatic" was the override). In addition to understanding the settings, do the users know the schedule for "automatic?"
- Some spaces (including those outside the Chemistry building) have local ventilation that is only active when the user calls the CHP to have it turned on. This is more common for canopy hoods over ovens and equipment. We inspected a lab that had instructions on how to contact CHP on the door, but not on the ovens or hood themselves, if you missed it on the way in.
- Local control located in another room. Looked at a space with a canopy, but the switch for the motor is in another room.
- Local control in which the switch isn't clearly labeled. In biology we had an older hood with a switch that said "on"...the problem was it only turned the light on. There was a second switch (which I ended up labeling clearly) that actually activated the fan motor. We also ran into this on ventilated BSC's -- one switch for the BSC (it hums) and a second for the penthouse exhaust fan (although in that case the ventilation error alarm eventually goes off if both switches aren't activated).


On Tue, Aug 31, 2021 at 2:37 PM Ralph Stuart <ralph**At_Symbol_Here**> wrote:
> >Remember though that NFPA 45 recommends you never let it go below 4 ACH even when unoccupied off hours.

Many teaching labs have a single "waste" hood which are kept on 24/7 to maintain some airflow through the room. They may not achieve 4 ACH that way, but teaching labs do have good control over when there is active chemical use in the lab. I suppose why this is an NFPA recommendation rather than a requirement.

- Ralph

Ralph Stuart, CIH, CCHO

For more information about the DCHAS-L e-mail list, contact the Divisional membership chair at membership**At_Symbol_Here**
Follow us on Twitter **At_Symbol_Here**acsdchas

Jeff Lewin
Director of Chemical Laboratory Operations
Research Integrity Office
Laboratory Operations
205 Lakeshore Center
Michigan Technological University

--- For more information about the DCHAS-L e-mail list, contact the Divisional membership chair at membership**At_Symbol_Here** Follow us on Twitter **At_Symbol_Here**acsdchas

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.