Date: Sun, 27 Nov 2005 16:01:02 -0500
Reply-To: esupport**At_Symbol_Here**SAFETYEMPORIUM.COM
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: esupport**At_Symbol_Here**SAFETYEMPORIUM.COM
Subject: Re: Clean room extinguishers
In-Reply-To: <4504600800CA7F4F9B644C8F0D54F8890160B80C**At_Symbol_Here**>

>Currently, our CalIT2 clean room spaces have been designed with "A-B-C"
>dry powder extinguishers only. Given the nature of the work being done
>in these clean rooms it concerns me to have these units as our only
>available option. I am considering putting CO2 type units in the main
>corridor of the clean room space as well. Any thoughts, for or against,
>would be greatly appreciated.
>Hope you are all having a great holiday weekend!
>Douglas Harvey (Chemical Hygiene Officer)
>UCSD-Environment, Health & Safety
>Desk Phone: (858) 822-1579
>Cell Phone: (858) 583-3257
>Email: daharvey**At_Symbol_Here**

I should start adding a standard disclaimer for my replies to this 
list:   My company sells _________, in this case, Cleanguard (and all 
other types) of fire extinguishers.

The best option for a clean room is going to be an Ansul Cleanguard 
extinguisher or equivalent.  These use DuPont FE-36 as the 
extinguishing agent, the best Halon substitute available, although it 
comes at  a higher price than CO2.  The principle advantages of FE-36 
over CO2 is that it discharges as a liquid so it can be lobbed a fair 
distance, there is less thermal shock, and CO2 is not A-rated.  A 
non-magnetic version is available in case your labs use high magnetic 
fields, too.

You can learn more at Ansul:

If you are looking for an extinguishing system to use instead of 
sprinklers, Ansul also has info on those:

You are right to be concerned about ABC units in that kind of 
environment.  They can cause far more damage than the fire they 
extinguish.  The dust gets everywhere, is abrasive, and is corrosive 
to circuit boards etc.  Saw a case when I was at the U of KY where a 
student put out a small Dewar flask of burning pentane with an ABC in 
a small computer/instrument room.  The fire itself did about $0 worth 
of damage; the extinguisher cleanup took days and probably caused 
appreciable damage to their instruments.

Nonetheless, a mixture of extinguishers may be in order, especially 
if a lot of flammable solvents are in use.   For example, a 13.25 lb 
Cleanguard is rated 1-A: 20-B:C, but a Foray dry chemical unit is 
20-A: 120-B:C.  Clearly, you have much more power in controlling a 
fire and preventing reignition with the dry chemical ABC unit and 
there could be times when this power could make the difference 
between saving or losing the entire lab.  Each fire situation is 

  If you go the mixed extinguishers route, workers in that area would 
use their training and common sense (talk about a house of cards, I 
know....) to select the appropriate extinguisher to use for a given 
situation.   For example, a small contained fire or small electrical 
fire might call for the FE-36 whereas a spilled burning liquid might 
require the dry chemical.   Check with your local fire marshal to see 
what kind of mix or extinguishers are required/acceptable.

Additional info about laboratory extinguishing considerations 
(including some other alternatives) can be found on my web page:

Best regards,

Rob Toreki
Safety Emporium - Lab & Safety Supplies featuring brand names
you know and trust.  Visit us at
esales**At_Symbol_Here**  or toll-free: (866) 326-5412
Fax: (859) 523-0606, 4905 Waynes Blvd, Lexington, KY 40513-1469

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