[neact] Oxygen bomb calorimeter explosion

From: Stephen Stepenuck <sstepenuck@xxxxxxxxx>
To: "neact@xxxxxxxxxxxxx" <neact@xxxxxxxxxxxxx>
Date: Sat, 18 Feb 2012 22:50:00 -0500
Hello NEACTers, et al.
    Although I know that those of you in high school chem probably do not
use bomb calorimetry,  those in college or university physical chemistry do.

The report below was posted to the ACS Division of Chemical Health and
Safety¹s [DCHAS-L] listserve this week.  It is shared here with permission
of the original author.

[Notes: 
The initial part of the report?prepared by a safety person, not a physical
chemist?does  have [at least] one technical slip in it: bomb calorimeters
are not used for determining heat capacities, but heats of combustion [which
can in turn yield other information of thermodynamic interest].   It is
probably true that the incident in question happened during the
determination of the heat capacity of the calorimeter system, a necessary
step toward determining heats of combustion.   An early step in that
procedure is to combust an accurately weighed sample of a pure substance
whose heat of combustion is known.  The temperature rise caused by that
combustion allows calculation of the heat capacity of the entire calorimeter
system. 

None of this should in any way diminish the value of the accident report?a
reminder to all who do use bomb calorimeters to a) inspect the bomb and
other units of the apparatus very carefully before each use, and b) to do
the maintenance recommended by the manufacturer?which includes sending the
unit back for new seals and testing at some appropriate interval.

Several years ago I visited a college PChem lab in New England a few days
after a similar explosion that resulted in the destruction of that bomb
calorimeter, so do rest assured that it can happen here.  Just because our
equipment maintenance budget is tiny or nonexistent, or because our
³supplies² budget is in similar territory, or because we do not have many
such firings in a year, that does not mean that the seals in this apparatus
are not deteriorating to the point of danger.

Let us learn from the misfortune of others, so that we can better care for
our students.
This accident can also be used as a reminder to each of us that any
experiment or demonstration that we do that involves pressure or vacuum can
use a careful safety review?now. ]
sjs

* * * * *
Report posted to the DCHAS email listserve February 15, 2012, by Debbie
Decker, University of California at Davis:
Hi:
 
I¹ve posted my report of this incident at
http://ucih.ucdavis.edu/docs/ll_CalorimeterFailure.pdf for your reviewing
pleasure.  The listserv chokes on embedded images.
 
This was a very near miss and thankfully, no one was injured.  If your
chemistry/chemical engineering/materials science folks use this technique
(and it¹s a pretty classic one), it would be good to follow up with them
about routine maintenance on the bomb vessel.  Don¹t forget undergraduate
teaching, where it¹s taught in p-chem lab.
 
Ya¹ll be safe out there,
Debbie
-------------------------
 
Debbie M. Decker, Campus Chemical Safety Officer
Environmental Health and Safety
University of California, Davis
1 Shields Ave.
Davis, CA  95616
(530)754-7964/(530)681-1799 (cell)
(530)752-4527 (FAX)
dmdecker@xxxxxxxxxxx
Co-Conspirator to Make the World A
Better Place -- Visit www.HeroicStories.com <http://www.heroicstories.com/>
and join the conspiracy
[neact] Oxygen bomb calorimeter explosion

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