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Previous by Date: Subject: Re: Chemical Hygiene Plan Date: Mon, 12 Apr 2010 15:49:42 -0400 Author: "Dr. Jay A. Young"

Next by Date: Subject: Survey Sample for Health and Safety Program development Date: Mon, 12 Apr 2010 14:08:52 -0700 Author: Magnus Ndukwe

In response to the dilution claim:

Remember that a refrigeratorÕs performance requires it to NOT ventilate the interior Ð at least not in an "air change" sort of way.  (This is true of freezers, environmental chambers, and glove boxes.)  In other words, whatever SPILLS in the walk-in will most likely STAY in the walk-in until the door is opened.  So long as a liquid has a non-zero vapor pressure at the walk-inÕs temperature, a puddle will become vapor given enough time Ð with no removal of the vapor.  What size of a spill would produce a flammable atmosphere in that walk-in?

SCENARIO
Consider a one-container spill in the walk-in:  4L of ethanol in a stagnant 28 m^3 (1000 ft^3 or 10 ft x 10 ft x 10 ft) space.  There is the potential for that to produce:

                (4000 ml ethanol / 28 m^3) * (0.69 g/ml)*(1000mg/g)*(1 ppm ethanol / 1.89 mg/m^3) = 52,000 ppm = 5.2%

of ethanol vapor in air.  The LEL for ethanol is 3.3%, meaning the flammable atmosphere develops THROUGHOUT THE SPACE well before the puddle fully evaporates, presuming ignition does notÉ uhÉ interrupt the concentration increase.  With decent mixing (there is likely a circulation fan to ensure good cooling throughout the walk-in), the AVERAGE concentration is probably a good value to sketch off of.  This will ensure the roomÕs air will be exposed to whatever ignition sources are in the space.  Remember also that ignition occurs when there is a local flammable atmosphere AT THE IGNITION SOURCE Ð which may occur at lower AVERAGE concentration values.

Convert the above scenario to your situation, and consider how likely such a spill would be.  Is that a risk you Ð or your organization Ð can live with?

All of this to say, flammable liquid storage in a walk-in refrigerator that does not have a classified electrical system is, shall we say, higher risk than you probably want to play at.  The fix would be to either "remove the ignition source" (i.e., re-tool the walk-inÕs electrical system) or to "remove the fuel" (i.e., prohibit flammable liquid storage in such a location).

Hope this helps,
-Nick
___________________________________
Nicholas J. Tsiakals
Division of Research Safety
Chemical Safety Section
University of Illinois at Urbana-Champaign
(217) 244 - 0682
www.drs.illinois.edu

"If we don't train students in risk management and safety procedures, then we're not training them for employment in modern industry.  If we want someone to turn up in a job and be productive, they can't do that if they're not safety aware."
    -- Prof. Thomas Welton, Head, Department of Chemistry, Imperial College London --

From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU] On Behalf Of Fred Simmons
Sent: Monday, April 12, 2010 12:29 PM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: Re: [DCHAS-L] Flammable storage in Walk-in Refrigerator

There are specific requirements in the NFPA codes:

NFPA 45
Standard on Fire Protection for Laboratories
Using Chemicals
2004 Edition

A.12.2.2.2.1 The use of domestic refrigerators for the storage
of typical laboratory solvents presents a significant hazard to
the laboratory work area. Refrigerator temperatures are almost
universally higher than the flash points of the flammable
liquids most often stored in them. In addition to vapor accumulation,
a domestic refrigerator contains readily available ignition
sources, such as thermostats, light switches, and heater
strips, all within or exposed to the refrigerated storage compartment.
Furthermore, the compressor and its circuits are
typically located at the bottom of the unit, where vapors from
flammable liquid spills or leaks could easily accumulate.
Although not considered optimum protection, it is possible
to modify domestic refrigerators to achieve some degree
of protection. However, the modification process can be applied
only to manual defrost refrigerators; the self-defrosting
models cannot be successfully modified to provide even minimum
safeguards against vapor ignition. The minimum procedures
for modification include the following:
(1) Relocation of manual temperature controls to the exterior
of the storage compartment, sealing all points where
capillary tubing or wiring formerly entered the storage
compartment
(2) Removal of light switches and light assemblies and sealing
of all resulting openings
(3) Replacement of positive mechanical door latches with
magnetic door gaskets
Regardless of the approach used (explosion proof,
"laboratory-safe," modified domestic, or unmodified domestic),
every laboratory refrigerator should be clearly
marked to indicate whether or not it is safe for storage of
flammable materials. Internal laboratory procedures should
ensure that laboratory refrigerators are being properly used.

NFPA 45 also refers to NFPA 70 - National Electrical Code

If this is like most of these I've seen it has lights in it that are not explosion proof and sits near a potential ignition source if the vapors collect and come out when the door is opened.

Fred Simmons
Savannah River Nuclear Solutions


From:        Paul Sonnenfeld 
To:        DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Date:        04/12/2010 01:16 PM
Subject:        Re: [DCHAS-L] Flammable storage in Walk-in Refrigerator
Sent by:        DCHAS-L Discussion List 
________________________________


May I suggest reviewing Chapters 27 and 34 of the International Fire Code (read-only versions are available from several sites).  Perhaps a visit from your local fire prevention officer would be appropriate.  Your collaborator needs to remember that when the fire department responds to the incident at his/her lab, he/she will have to provide some answers.  If you work for a private-sector employer who is not self-insured, I'd also suggest reviewing your fire and general liability insurance policies for specific language.

Unfortunately, it sounds like your collaborator has become complacent.

Respectfully yours,
Paul Sonnenfeld, CPEA

________________________________
Date: Mon, 12 Apr 2010 10:33:03 -0500
From: rlustwerk**At_Symbol_Here**VERIZON.NET
Subject: [DCHAS-L] Flammable storage in Walk-in Refrigerator
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU

Hello All,

I have a collaborator who is storing organic peroxides, solid and liquid, in a walk-in refrigerator/freezer.  They have done so for a number of years.  One of the new organic peroxides is a liquid with a low flashpoint (class IB flammable liquid).  At our facility, any flammable liquids that require refrigeration are stored in flammable-safe refrigerators.  I have seen the walk-in refrigerator in question on a previous occasion and was not impressed by the housekeeping--spills on the floor that had not been cleaned up, poor organization and poor lighting.  I do not have juristiction over this space, but want to offer advice that pertains specifically to walk-in size refrigerators or cold rooms.  I'm sure that one of the arguments that this collaborator will present is that the walk-in is large enough to offer sufficient dilution to prevent an LEL from developing.  Any regulations, stories, advice or help would be wonderful.  In addition, how does one address the issues that these materials are both flammable and oxidizers, when there may be storage with other flammable liquids--should there be entirely separate storage?

regards,
Rigel Lustwerk

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