Date: Mon, 22 May 2006 17:25:42 -0400
Reply-To: Yung Morgan <pmorgan**At_Symbol_Here**EHS.UMASS.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: Yung Morgan <pmorgan**At_Symbol_Here**EHS.UMASS.EDU>
Subject: Venting flammable storage cabinets. Thanks
Comments: cc: jim field
Dear members,
Thank you so much for all your responses for my question on" whether or not
to vent flammable storage cabinets". The responses were varied but so very
informative and thorough.   Here are some examples:
!. "NFPA 30-2003, Flammable and Combustible Liquids Code, does not require
that a flammable liquids storage cabinet be provided with ventilation or
exhaust.  It does compromise the integrity of the cabinet because the
cabinet is intended to keep a fire outside from getting at the materials
inside for at least 10 minutes, said time presumably being sufficient for
evacuation of the area.  This is especially true when the user merely
removes the bung from the 2-inch openings on the cabinet and leave them
2. Another direct quote from NFPA 30 ." However, it is recognized that some
jurisdictions can require storage cabinets to be vented and that venting can
also be desirable for other reasons, such as health and safety. In such
cases, the venting system should be installed so as to not affect
substantially the desired performance of the cabinet during a fire. Means of
accomplishing this can include thermally actuated dampers on the vent
openings or sufficiently insulating the vent piping system to prevent the
internal temperature of the cabinet from rising above that specified. Any
make-up air to the cabinet should also be arranged in a similar manner.
If vented, the cabinet should be vented from the bottom with make-up air
supplied to the top. Also, mechanical exhaust ventilation is preferred and
should comply with NFPA 91, Standard for Exhaust Systems for Air Conveying
of Vapors, Gases, Mists, and Noncombustible Particulate Solids. Manifolding
the vents of multiple storage cabinets should be avoided."
3. Not vent the cabinets at all and requiring that some other types of odor
absorbing materials and" door closing and locking of the cabinets to keep
the odors down.
4. From our own hazwaste officer and emergency response leader, Jim Field:
My understanding is that some institutions require that venting be  part of
all cabinets installations. The rational behind venting is really more of a
personnel exposure issue. The problem has been that many short chain
volatile once opened will off gas vapors into the cabinets crating a vapor
filled container. We see this with especially the ethers and some of the
more volatile acids and bases. These more corrosive liquids present an even
greater exposure problem and will eventually corrode the cabinets. Venting
these storage cabinets creates a safer environment in the lab and extends
the life of the cabinets.
Some of the major problems associated with venting flammable storage
cabinets is if they are installed improperly they can increase the hazard.
The connections to the venting system must follow the mechanical code. The
cabinets flash arrestors must be open and used for the supply air and as I
understand the problem the flow rate must be very low. The idea is that a
high volume flow rate might draw the flame form an impinging fire into the
cabinet defeating its purpose.
We do have some vented cabinets on campus. The flammable storage cabinets in
Conte chemical stock room are vented and I think the under fume hood
cabinets in this building have openings for passive exhaust ventilation. I
would have to look to verify that.. If you remember, the fire in Conte the
flames were all drawn into the fume hood. The fume hood was destroyed but
the fire did not extend into the lab or adjacent storage areas. In fact the
samples and some of the apparatus in the hood were salvageable.
I don't have enough room to list all the responses but if anyone would like
to see them, either for or against venting the cabinets, I can send them
individually . Again thanks a million for all your help, you are "a terrific
group", to quote Monona. 

Yung Morgan, MsPH
Chemical Safety 
Industrial Hygiene Services
Environmental Health and Safety
117 Draper hall 
UMASS,Amherst MA 01003
phone (413)  545-2682
Fax  (413) 545-2600
email : pmorgan**At_Symbol_Here**

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