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Date: Wed, 24 Jun 2009 12:35:19 -0400
Reply-To: Margaret Rakas <mrakas**At_Symbol_Here**SMITH.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: Margaret Rakas <mrakas**At_Symbol_Here**SMITH.EDU>
Subject: Fwd: Fire w/Rotovap Reported By Canadian Colleagues
This came to me through another listserv. I wanted to share it w/DCHAS
colleagues, and also point out that while there have been several fires
in US academic labs in the past 6 months, other than the UCLA fire,
which made headlines for the death of the researcher, we have heard very
little in terms of analysis of what went wrong. I applaud the folks at
UCalgary who have gone public with a very detailed analysis. I wish
administrators who instruct their EH&S folks to say nothing would see
the value of this posting. I have already sent it to colleagues at
other institutions as well as my own chemistry department.
The above is my personal opinion only, not legal or business advice,
and may not reflect the opinion of my employer or any group to which I
belong.
Margaret A. Rakas, Ph.D.
Manager, Inventory & Regulatory Affairs
Clark Science Center
Smith College
Northampton, MA. 01063
p: 413-585-3877
f: 413-585-3786
>>> Tom Williamson 6/23/2009 5:40 PM >>>
Hi everyone
We've had an incident I'd like to share with you. I encourage you to
pass this information along to your colleagues as applicable to prevent
a similar incident in one of your facilities.
A small fire started in a laboratory involving a rotary evaporator
(detailed synopsis follows below). The fire was extinguished by the lab
worker using a portable fire extinguisher but not before enough heat
accumulated at the ceiling to activate a nearby sprinkler head.
We were lucky in that the fire was small and contained to the rotary
evaporator but the repercussions from the activation of the automatic
fire suppression system were significant. Water from the sprinkler
system percolated down through two floors of the building, soaking
cardboard boxes & contents and computers resting on the floor.
The water eventually ended up in the high energy electrical vault
forcing a hasty power shutdown for the entire building. The rapid
shutdown terminated several experiments in progress and left freezers &
incubators without power for several hours.
Tom Williamson
Fire Prevention Officer
Environment, Health & Safety
University of Calgary
P: 403-220-8105
A Safety Culture is Defined by what happens when nobody is watching!
HAZARD ALERT - ROTARY EVAPORATOR (ROTOVAP) FIRE
A fire started while a worker was conducting an experiment using a
rotovap and approximately 100 mls of carbon disulfide. (CS2)
ROTARY EVAPORATOR - ROTOVAP
CARBON DISULFIDE ( CS2)
Extremely flammable liquid and vapor. Vapor may cause flash fire.
Conditions to avoid: Heat, flames, ignition sources and incompatibles.
Autoignition temperature: 90C, Flashpoint: -30C, Boiling point: 46C,
Density: 1.26, Vapor Density: 2.6 (Air=1)
Upon start up of the rotovap the heating element was activated for the
heated waterbath. The rotovap operates in a vacuum which serves two
purposes. The first is designed for lowering the internal pressure of
the system, enabling in such way distillation processes at lower
temperatures. The second is a practical one. i.e., to guarantee the
sample flask doesn't fall into the warm bath.
Upon initiation of the experiment a small amount of CS2 flashed from
the sample flask into the solvent receiver. (It was determined later
that this was because a stronger vacuum than required was applied via
the vacuum screw adjuster.) As a result the procedure needed to be
restarted. In order to re-start the procedure, the solvent receiver was
detached from the rotovap and the reflux valve was closed to maintain
the vaccum. (It was determined later that not enough vacuum was applied
in order to maintain the sample flask and the clamp failed to maintain
the flask adhered to the tip of the rotating shaft.)
Once the solvent receiver was detached the worker then went to the
fumehood about 8 m away to recover the CS2 from the solvent receiver in
order to restart distillation. The worker was under the direct
supervision of a 'competent worker' as the worker involved in the
incident had not yet been deemed competent in the use and handling of
CS2. The worker who was supervising momentarily stepped away at the time
the incident occurred.
While at the fumehood the worker heard a noise that sounded like an
explosion and turned to find flames coming from the vicinity of the
rotovap. The worker extinguished the flames with a nearby fire
extinguisher About 30 seconds later an overhead sprinkler activated the
building fire system which led to further complications arising from the
water generated by the sprinkler activation.
There are three hypothesis about what caused the explosion and
subsequent fire. The first is that as CS2 is more dense than water ,once
the clamp failed and the sample flask fell, the vapor rose to the top of
the water bath and then moved down to the vicinity of the heating
element where it ignited the vapor and caused the explosion. The second
is that the vapor flowed along the surface of the lab bench to an
ignition source and flashed back burning the electrical outlet directly
behind the rotovap and starting the fire. The third is that when the
clamp failed and the sample flask fell, water from the bath splashed
onto the electrical outlet directly behind the rotovap causing the
explosion.
LEARNINGS
· Prior to using CS2 it should first be determined if it is
required for the task or if it can be replaced with a less hazardous
substance. A hazard review should be conducted of the replacement
product to ensure it doesn`t create an alternate hazard.
· Standard Operating Procedures (SOP`s) should be written and
reviewed by workers prior to all hazardous operations.
· Explicit written instructions should be incorporated into the
rotary evaporator Standard Operating Procedure regarding the direct
close surveillance of it`s operation until stationary solvent
distillation is secured. (No pressure build up)
· At the time of the incident the rotovap was located outside
of the fumehood. Had it been inside the fumehood the fire may still have
started but would have been contained and extinguished before the
sprinkler head was activated.
· Mechanical clamps on rotovaps should be inspected for defects
and wear on a regular basis and replaced as required.
· Workers must be aware of the properties of the chemicals they
are working with. (i.e. CS2 is denser than some other solvents and a
different amount of vacuum is required to hold the sample flask in
place.)
· Workers who are not yet deemed to be `competent`in a task
must be under the direct supervision of a competent worker at all times.
The work must stop, or someone must take their place, if the supervisor
is going to be absent at any time during the process.
· Workers must be supplied job specific training applicable to
all tasks they do as well as general safety training such as WHMIS.
· A training needs analysis should be set up for all lab
workers to include both lab specific and general safety training. All
workers must undertake the required training before work begins.
· Inspections of the work area should be conducted on a
pre-determined ongoing basis.
· Hazard Identification and Assessment for should be conducted
for every task.
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