Flammable Chemical Storage in Laboratory Refrigerators
We recently had a flammable chemical spill inside of a household refrigerator. This was a near miss that had the potential for a fire, explosion and serious injury.
Flammable chemicals that require refrigeration must only
be stored in a refrigerator that is designed for the safe storage
of flammables. A flammable liquid is defined by the
fire code as having a flash point of less than 100°F (38°C).
The new Globally Harmonized System of Classifying and Labeling Chemicals (GHS) label for flammables, shown to the right, can be found on some chemicals now and will be on most chemicals in the future. This label makes it even easier to identify your flammables. We look for improperly stored flammables during our annual
Laboratory Safety Surveys. When laboratory workers
are asked to remove flammables from a refrigerator that
is not designed for their storage I am often asked “why?”
and “what type of refrigerator should I purchase that will
allow me to store my flammables safely?”. I hope this article
will explain the necessity to use the proper refrigerator
for your laboratory, and how to choose the appropriate one for the task.
The storage of flammable materials in a household-type refrigerator,
or a laboratory refrigerator that is not designed
for flammable storage, is risky practice. This is due to the potential
of vaporization of these materials in the closed space
and potential explosion. Explosion of flammable
vapor from a spark
generated by electrical
contacts from relays,
switches, or thermostats
that could ignite
flammable vapors inside
While this has not happened
on our campus,
there are many reported
other institutions that
have caused injuries
and property damage
from this type of explosion.
Below are photos and descriptions of the 3 types of
refrigerators that can
be found in the laboratory.
1. Ordinary Household Refrigerator.
Household refrigerators like the one shown below
have internal components such as thermostats, relays and
switches. All these components have the capability of generating a spark. If a spark is generated it is capable of igniting
accumulated vapor released from flammable liquids stored inside the refrigerator. This type of refrigerator is the least costly and because
of the lower cost many labs have only this type of
refrigerator. Flammable materials must never be stored in
this type of refrigerator.
2. Flammable Storage Refrigerator
refrigerators, like the
one seen below are UL approved
for storage of
refrigerators have no
switches, or thermostats
that could ignite
inside the cabinet.
refrigerators also may
features such as
thresholds, self-closing doors, magnetic door gaskets, and
special inner shell materials that control or limit the damage
should a reaction occur within the storage compartment.
A label stating “Flammable Materials Refrigerator:
Keep fire away” can identify such refrigerators. The refrigerators
must be U.L. Listed as Flammable Material
Flammable storage units cannot be placed in a room containing
explosive vapors but chemicals that exude explosive
vapors can be safely stored inside them. These refrigerators
are also called lab-safe, fire-safe and/or explosion
safe refrigerators. These refrigerators are more costly than
the household refrigerator types but they must be purchased
if you are planning on storing flammables in the
3. Explosion Proof Refrigerator
Explosion proof refrigerators
like the one seen below are rated UL
explosion-proof and are
similar in design to the
flammable storage units,
but also have all operating
components sealed against
entrance of explosive vapors.
boxes are also sealed after
connections are made.
These units are approved
for storage of volatile materials
in areas with explosive
atmospheres and are the
most costly of all refrigerator types.
This type of refrigerator is
only required when storing flammable materials in an area
with an explosive atmosphere such as a solvent dispensing
room. Explosion-proof refrigerators have very limited use
on campus and require special hazardous-location wiring
rather than simple cord-and-plug connections. Please contact
Lee Stone, IUPUI Laboratory Safety Manager, at 278-
6150 if you feel you have a need for an explosion proof
Since TEMED or Sigmacote are the only flammable materials
stored in the refrigerator for many labs, Sigma was
contacted concerning storage options for these chemicals.
Sigma Corporation representative, Dr. Jeffrey Howard, responded
that storage of both of these materials in the refrigerator
is optimal but it is not necessary. Both of these
chemicals may be stored in a solvent cabinet as long as the
lab is maintained at room temperature without extreme
fluctuations. Dr. Howard states that both chemicals are
stable at room temperature for several months. Due to the
moderately low cost of both of these chemicals, it is recommended
that they be stored at room temperature if there
is no flammable storage refrigerator available. Date the
chemical when received and dispose of it after several months
to insure effective results with its use.
Please help keep our campus safe. Identify the type of refrigerators you have and remove any flammable
materials if your refrigerator is the type not approved for the storage of