Date: Fri, 18 Feb 2005 09:02:20 -0500
Reply-To: Ralph Stuart <rstuart**At_Symbol_Here**>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: Ralph Stuart <rstuart**At_Symbol_Here**>
Subject: Summary of Thermo MIRAN SapphIRe replies
Comments: To: SAFETY**At_Symbol_Here**

Thanks to everyone who replied to my inquiry about the Thermo MIRAN
SapphIRe. I have collated the responses below.

My current thinking is that a combination of the Thermo MIRAN (about
$25,000) and a good PID (about $4000) makes reasonably good sense for
lab emergency response. As several people pointed out, the responses
from these instruments can still give ambiguous results. To try to
reduce this ambiguity, if the instrumentation is funded, I hope to
spend some time visiting various lab buildings under normal operating
conditions to develop a baseline to compare response situation
readings with.

- Ralph

One of our QC labs at a plant purchased a PID for "monitoring" an
organic that has no warning properties.  Had I known about it, I
would have advised against it!  As I could have predicted, it would
occassionally trip (when moving lab waste cans around, etc...) and it
freaked the employees out ... they were thinking they were being
exposed to the hazardous material that had no warning property!

At our research facility, a Chemist had attached a small portable PID
unit just at the face opening of the hood.  His reaction generated a
highly hazardous compound that he was "monitoring" for.  He marched
into my office stating unacceptable levels were being generated (even
though the off-gases were vented to a scrubber connected to the
reaction).  I used a compound specific gas detection tube and found
non-detectable concentrations of the material were present, even
though the PID was still reading well over 10 ppm.  After assessing
the situation, I discovered a beaker in the back of the hood
containing a low level of liquid and several disposable pipets (can't
remember what the organic was in the beaker).  I removed the beaker,
and the PID immediately dropped to a couple of tenths of a ppm.

The morale of the story:  A PID is good to tell you a "grand total"
of what's around (keep in mind each compound has a different response
factor), but it doesn't tell you what's around.  If you know what you
need to look for, there are better alternatives for gas detection
equipment.  Here's a good web page to use:


In my time in Monsanto's Corporate IH Department in the '80s I used a
Miran to do research on lab hood performance with Freon 22.  The Miran
worked well for that purpose.  I'm sure the unit you are looking at has
better electronic support for quantitation.  The problem with
emergencies is that you never know what you need to detect and therefore
can't calibrate the units for the IR frequencies that minimize
interference and cross sensitivity.  The Monsanto Corporate Research
Safety Department tried to use the unit I had, after my work, for
emergency response.  They generated more questions than answers in that
mode of use because of the calibration issues.

When it comes to lab emergencies, except with super toxics, you are
worried about flammable or explosive concentrations of solvents that may
be present as vapors in percentages, not PPM.  I'd recommend simple
detector tubes as a first line if specific component analysis is needed
or believed critical.  That would require labs to have these on hand as
part of an emergency response kit.  Otherwise, a PID of FID units, PPE
for responders and good ventilation to clear the area would be my
approach.  None of these units are good for particulate material and
have limited value for odor complaints because of personal sensitivity
at PPB levels for most odor complaint related materials.

I can also say that as Director of S&IH at Schering-Plough, I followed
the same strategy in the research labs there.  We used Mirans for
detection of specific compounds in known, not emergency situations.


I've generally heard good things about the Sapphire, which has actually been
on the market for a number of years.  The Homeland Security department and
the military reportedly use these for chemical weapon screening, which would
seem to be an endorsement of sorts.  Thermo is a good company, and they have
good product support.  That's the key - these units, and others like them,
require some knowledge in interpreting results and achieving useful data.
They also have to be calibrated correctly, and the compounds you're looking
for must be in the unit's library.  Also, they are good down to only about a
part per million for most volatiles, so don't count on finding things in the
ppb range as a general rule.

Hope this helps.  I seem to recall seeing an online review from DHS
somewhere if you want more info.


My past experience with older 1A and 1B MIRAN units is that they are more
trouble than they are worth in an emergency response setting (and at most
other times as well), especially in labs where you generally have some idea
of what you are dealing with.  When given a choice I have set things up with
multi-gas meters and a variety of sensors (e.g. Draeger mini-warn).  With
that said, I recently investigated the use of the SapphIRe unit for a
project and was re-assured that it was more reliable, easier to use, etc.
Sorry no personal experience though.  Might be a good question for the AIHA

James Kapin, MPH, CIH
Advanced Chemical Safety
858-874-5577 Cell 619-990-5955


I have not used this model, but I am familiar with the old MIRAN units.  The
old MIRAN was pretty good as a qualitative unit but we had problems with
mirror alignment because the unit was quite old when I started using it.

It should be more selective than the PID in situations involving several
chemicals, however it would be important to check it out against another


I don't have experience with that particular instrument, but I have a
very old version (barely portable) that we have used.  This instrument
is reliable for the specific compounds for which we have a window
(methyl methacrylate and a few others), but it is not very accurate when
there are several chemicals at once.

We are in the process of purchasing a GrayWolf TVOC PID sensor with an
additional three electrochemical gas sensors for our gases of most
specific interest.  I will let you know what we think once we try it
out.  We chose this instrument because we are purchasing their IAQ probe
(temp, RH, CO, CO2) and their anemometer, all of which datalog onto a

Good luck!

Ralph Stuart, CIH
Environmental Safety Manager
University of Vermont
Environmental Safety Facility
667 Spear St.
Burlington, VT   05405

fax: (802)656-5407

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