Demystify: 

Ralph,
Answer to question 1: Yes, I did before COP26, but no other gas could
definitively prove containment.
Answer to question 2: No. I only used this test for baseline acceptance to
prove/disprove operational functionality as installed. Most fume hoods pass
under ideal test conditions. My experience is that once installed those
same performance requirements are sometimes not met.
Answer to question 3: No. But your question this raised another question
from my perspective. Which should have the higher priority, lifetime impact
of the hood regarding lifetime climate impact with or alternatively to
lifetime energy efficiency compared to is it controlling acute or chronic
exposures while the hood is in use during less than a lifetime of use?
I had a certified ME/PE state that it was impossible for his fume hood not
to control as installed, even with ASHRAE 110 tests confirming the failed
performance. I purchased a theatrical "fume" generator and under the guise
of the architect, ME/PE and company President, inserted it into the hood and
the smoke rolling out into the lab clearly showed to everyone watching, that
indeed the hood was significantly exhausting into the general lab area. The
ASHRAE110 test results were not only accepted after that demonstration, but
demanded of every new hood during commissioning.
Boils down to what is our primary objective? I'll stay with controlling
occupational exposures for the short and long term.
BruceV

-----Original Message-----
From: ACS Division of Chemical Health and Safety On
Behalf Of Ralph Stuart
Sent: Friday, November 12, 2021 7:45 AM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: [DCHAS-L] SF6 fume hood certification

With COP 26 finishing up, those of us involved in assessing fume hood
performance are thinking (again) about the use of SF6 as a tracer gas in
fume hood evaluations (SF6 has 22,800 times the greenhouse gas potential of
CO2). With this in mind, I have a couple of questions for the list:

1. Have CHAS members investigated alternatives to testing every fume hood
using the ASHRAE 110 tracer gas test as written, using SF6 as the tracer
gas?

2. Has anyone changed their fume hood acceptance protocol to try to reduce
the amount of such tests that are conducted for climate impact mitigation
purposes?

3. Has anyone calculated the relative climate impact of doing a
commissioning test of a hood using SF6 relative to the lifetime climate
impact of the energy required by that hood?

My personal opinion is that the test as written was designed to address
specific design challenges associated with fume hoods when the standard was
written in 1985. And it is based on a rather stilted scenario (a single user
in a specific location with chemistry which is properly located in the
hood). In my experience, essentially all hood installations since 1990 were
designed and specified to pass that test and so additional 110 tests seldom
generate actionable information. I am curious if other CHAS members have
other experiences with this test?

Thanks for any information about these questions.

- Ralph

Ralph Stuart, CIH, CCHO
Environmental Safety Manager
Keene State College
603 358-2859

ralph.stuart**At_Symbol_Here**keene.edu

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