Reza,
Look at Page 13-101 (2002)
No. (11)
Chris Payne
----- Original Message -----
From: "Reza Esmaeili" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, September 25, 2007 11:07 AM
Subject: RE: How much Water Supply Duration is Important?
Hi Travis! Nice to see you are writing to me again!
NFPA says that "...The lower duration value is permitted where remote or
central station waterflow alarm service is provided, then It is expected
that the fire department or fire brigade will be made aware of the fire
more quickly..."
So if a central station waterflow alarm service is provided, then how
many percent is permitted to reduce the water supply duration?
I don't know why NFPA never made a relation between water supply duration
and distance to local fire brigade . So it seems that the water supply
durations stated in NFPA is to control water without help of local fire
brigade.
The above NFPA sentence confuses me, let me explain the reason of water
supply duration in two way:
1- Water supply duration is NOT related to how much close the local fire
brigade is, it depends to how much time it takes to control or extinguish
fire based on hazard type, if the fire brigade department comes in only 3
minutes, they still need water to extinguish fire (they don't bring enough
water), Carig, you said "You can not guarantee that the fire will be
controlled in only 45 minutes regardless of how soon the local fire
brigade responds" So If duration is not related to distance to local fire
brigade, so why NFPA says above statement and allow to reduce duration?
2- Water supply duration IS related to how much close the local fire
brigade is, however no one can guarantee if the local fire brigade will
come in less than 5 minutes, but when they come sooner they will help
sprinkler system and the fire would be controlled soon and less duration
is needed, so usually factories which are nearer to local fire brigade
need less water. If sprinklers can extinguish fire in 90 minutes without
help of fire brigade department, then sprinklers with the help of local
fire brigade may extinguish water 45 minutes, the sooner local fire
brigade comes, the sooner water is controlled, right?
I don't know which theory is right, may be no one! what is the right
theory in your opinion?
Thanks,
Reza
[EMAIL PROTECTED] wrote:
Duration is critical. You can not guarantee that the fire will be
controlled in only 45 minutes regardless of how soon the local fire
brigade responds. Plus, are you relying on them to bring additional
water if needed? Their supply within the trucks is very limited so as
they run out they may have to leave the site to refill but in any case
that could result in a delay in their attack and an out of control fire
scenario.
I would never for any reason see the reduction of the duration as
specified in NFPA having any value. Quite the contrary, it would result
in a non-compliant system and put you responsible for any damage due to
the ineffectiveness of the inadequate system.
In the building codes we have there is wording stating that even if a
particular fire system is not required by the code, if you install it,
you must still install it according to the applicable codes. So even if
no one was going to review or approve it, you must still design and
install it according to the codes that govern it.
Craig L. Prahl, CET
Fire Protection Group
Mechanical Department
CH2MHILL
Lockwood Greene
1500 International Drive
PO Box 491, Spartanburg, SC 29304-0491
Direct - 864.599.4102
Fax - 864.599.8439
[EMAIL PROTECTED]
http://www.lg.com
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Reza
Esmaeili
Sent: Tuesday, September 25, 2007 10:52 AM
To: [email protected]
Subject: How much Water Supply Duration is Important?
Hi,
I know it is very important to take care of water supply duration, but
how much important?
Imagine fire brigade is very close to the factory and will come to
extinguish fire in less than 5 minutes.
If for an extra hazard occupancy which I need at least 90 minutes of
water supply for my wet pipe sprinkler system demand, I reduce it to 45
minutes, then what will happen?
If I don't care about my required pressure and flow, then the entire
system will fail, but if I reduce water supply duration, then system
will work properly but only for 45 minutes, so if the fire brigade can
come in 5 minutes, there wouldn't be a serious problem, Imagine that no
one is going to approve the system (No insurance, ...). I just want to
analyze fire behaviour in this case, it is not a real project.
Thanks,
Reza
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