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Date: Thu, 26 Apr 2007 09:45:33 -0700
Reply-To: Russell Vernon <russell.vernon**At_Symbol_Here**UCR.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: Russell Vernon <russell.vernon**At_Symbol_Here**UCR.EDU>
Subject: Speciality Calibration Gas source inquiry
Dear Fellow Chemists,
In California we are being required to test some of our fume hoods with
a tracer gas. We are also being encouraged to reduce our greenhouse gas
emissions. The standard method, ASHRAE 110-1995, calls our sulfur
hexafluoride as the tracer gas of choice. It takes about 0.5 to 1 kg of
tracer gas for each test. SF6 has 23,900 times the global warming
potential of CO2 largely dues to its stability and very long residence
times in the atmosphere. ASHRAE 110-1995 allows for alternative tracer
gases to be used but requires that they are similar in weight, stability
and detection limits to SF6.
The best alternative I've found so far is hexafluoropropene [116-15-4].
The current director of our Air Pollution Research Center
(www.aprc.ucr.edu ) assures me that
hexafluoropropene will hang around in the atmosphere only 4-5 days so
will not have the dramatic negative environmental impact of SF6 (also it
will not deplete the stratospheric ozone).
I have found a local fume hood certifier that is set up to conduct the
ASHRAE 100-1995 test who is willing to try a new gas, but his detector
is calibrated to SF6.
We contacted the manufacturer of his Q200 leak detector and they need a
certified calibration gas source. Normally they use a 1% mix of gas in
nitrogen, and fill a 0.6 liter bottle with it to a pressure of between 4
and 10 bar. The set the leak rate of the gas at either 1 x 10-7 or 1 x
10-6 cc/sec, which corresponds to 0.1 and 0.2 ppm respectively.
Can you recommend a lab, supplier or manufacturer that would be willing
to create a certified mixture of 1% hexafluoropropene in nitrogen?
(The manufacturer of the Q200 is in the UK so a European source may be
the best.)
Sincerely,
-Russ
Russell Vernon, Ph.D.
UC System-wide Field Safety Working Group Chair
http://ehs55.ehs.uci.edu/fieldsafe/index.jsp
Laboratory / Research Safety Specialist & Integrated Waste Manager
Environmental Health & Safety
University of California, Riverside
900 University Ave.
Riverside, CA 92521
russell.vernon**At_Symbol_Here**ucr.edu
www.ehs.ucr.edu
Direct: (951) 827-5119
Admin: (951) 827-5528
Fax: (951) 827-5122
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