CO2 is often preferred in the developing world because it is
universally available - the installation cost may not actually be the
defining factor as the cost and difficulty of gettting a recharge can
outweigh other benefits. I saw an u/s chemical gas system in the
Sudan a couple of months ago, it had ben like that for a year as
there was a problem getting a recharge through customs. If life
safety is an issue (ie if the space is regularly occupied) then agent
of choice is either an inert but life safe gas like Inergen or a
chemical gas like FM200 . Some jurisdictions and insurers do not
favour FM200 . Don't forget there are pending amendments to NFPA 2001
which will affect things like overpressure flaps.
New agent Noveon looks tasty but has limited availability in many
places and I have seen prices which look out of line with competing
products.
But the real question is: What's wrong with sprinklers or mist ? I
specify these all the time for IT and comms rooms.
Stewart
Stewart Kidd
Loss Prevention Consultancy
Cambridge, England
Reza, No I minute is OK. BUT be careful of over pressurization due
to the high rate and high
concentration. The intent was to allow designers some latitude when
using very high concentrations
thus minimizing pipe sizes and preventing over pressurization the
room and popping windows and such.
See venting consideration and calcs in 5.6
Most computer rooms are protected under the "Dry electrical Hazard"
as you have done. I believe that
you may take advantage of the extended discharge time if you wish or need to.
Now the big question! Why CO2 when other clean agents are safer,
cheaper and arguably the industry
standard?
Burton Ford
SET, CFPS
Member AFAA
[EMAIL PROTECTED]
267-487-1000
Fax 267-487-1010
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-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On
Behalf Of Reza Esmaeili
Sent: Thursday, August 23, 2007 10:19 AM
To: [email protected]
Subject: Carbon Dioxide System Discharge Time
Hi all,
For designing a total flooding high pressure carbon dioxide system
in a 3,500 cubic feet computer
room with electrical equipment and cable runs, I have specified my
room as "Dry electrical hazard"
with flooding factor of 0.083 lb/cubic.feet and 50% design
concentration according to NFPA-12.
My questions are as below:
1)- Is a computer room fire a deep seated fire?
2)- NFPA 12 states that "For deep-seated fires, the design
concentration shall be achieved within 7
minutes, but the rate shall be not less than that required to
develop a concentration of 30 percent in
2 minutes." Is it a problem if the total discharge time would be
only 1 minute for this case?
Many thanks for your help in advance.
Reza
---------------------------------
Pinpoint customers who are looking for what you sell.
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