Rick and Brad,
The original intent of NFPA 14 pre 1990's editions was to provide a 250
gpm hose stream for fire department use at the floor of fire department
operations with a residual pressure of 65 psi flowing 250 gpm. This was
based on high rise hose pack that the fire department were using which
consisted of 2 1/2 inch hose, 100 ft pre-connected, with a non-automatic
2 1/2 inch Rockwood hose nozzle (solid/spray). With a residual pressure
of 65 psi at the fire dept hose valve on the standpipe the Rockwood
nozzle could throw a 250 gpm stream a minimum of 50 ft.
At the One Merridian Fire the fire department high-rise hose pack
consisted of 1 3/4 inch hose with 1 1/2 inch couplings, 100 to 150 ft of
pre connected hose, with 1 1/2 inch, automatic Task Force nozzles.
Actual testing after the fire indicated that the combination of 1 3/4
inch hose and automatic nozzle could not produce the 250 gpm flow that
the old 2 1/2 inch hose and Rockwood nozzle combination could produce at
65 psi residual pressure at the fire dept hose valve. In some of the
testing pressures in excess of 300 psi at the fire dept hose valve was
required to produce a flow in the vicinity of 200 + gpm with the TTF
nozzle and 1 3/4 hose combination.
The designer of the standpipe system needs to discuss in detail with the
appropriate fire department operations personal as to the real high-rise
operations and hose stream deployment tactics actually used on the fire
ground.
The standpipe system was designed to NFPA 14 1984 Edition requirements
as per City of Philadelphia requirements, at time the high rise pack
consisted of 2 1/2 inch hose with Rockwood 2 1/2 inch nozzle. At time of
fire the high rise pack consisted of 1 3/4 inch hose w 1 1/2 inch
couplings, with 1 1/2 inch TFT automatic nozzles which completely
changed the original intent of NFPA 14 to provide 250 gpm for fire hose
stream operations and hydraulic requirements to produce the 250 gpm
through the 1 3/4 hose. The standpipe system is a very important part of
the fire departments operations at a high rise building and the fire
department needs to be consulted about the fire ground operations SOP in
order to address the particular high rise pack equipment used by the
fire department and any unusual hydraulic requirements these operations
introduce into the design of the standpipe system.
Have a fire safe day!
Regards
Jim
DAVIDSON ASSOCIATES
Fire Protection Engineering P. O. Box 4010
Code Consultants Greenville, DE 19807-0010
Medical Gas Systems Engineering (302) 994-9500
Fax (302) 994-3414
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-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
Matsuda, Richard
Sent: Wednesday, February 19, 2014 10:45 AM
To: [email protected]
Subject: RE: 100 PSI requirement at top of Standpipe
Brad,
Here is my explanation of the 100-psi requirement, and I apologize to
any one that I might offend with such a long opinionated response. This
is my pet peeve, and I have tried my best to educate the fire service as
to what they could expect during a high-rise fire condition.
The old standpipe pressure requirement was 65-psi. This changed in the
late 1980's or early 1990's after the One Merridian Place fire where two
firefighters died whiile they were searching several floors above the
fire. The lack of pressure avaiable in the standpipe allowed the fire to
grow and extend to their search area. The standpipe system had PRV hose
valves installed which were improperly adjusted to a pressure too low
for fire operations.
The NFPA-14 committee decided that since the automatic nozzles in use at
that time required an optimum 100-psi nozzle pressure, that this magic
number (100-psi) would be a good starting point. There was a long
discussion with numerous tests of various nozzles and hoses. Too little
pressure did not provided enough water and too much pressure made it
very difficult to manuver the hose around corners. The minimum 100-psi
at the hose valve was a "reasonable" pressure to allow "adequate"
pressure to the nozzle while flowing a "sufficient" quantity of water
taking into account different friction losses for different lengths and
diameters of hose that the different fire departments would use. The
maximum 175-pis was used to match the existing maximum pressure for the
sprinkler systems connected to the standpipe, and also allow a range for
minimum and maximum pressures that the PRV's could satisfy.
Since then, numerous changes have been made in fire department
operations. There are now low pressure automatic nozzles, low friction
loss hoses, and many departments just use a non-automatic adjustable
nozzle in their high-rise packs. Since the older buildings may only have
50 to 65-psi at the hose valve while the newer buildings have 100-psi,
the manufacturers also have produced an in-line pressure gauge that can
be installed at the hose valve so the firefighter can see the pressure
available from the hose valve and make adjustments accordingly.
Presently, it's really up to each AHJ to decide on an SOP for high-rise
fires in their jurisdication knowing that the standpipe systems have
pressures that can vary from 50 to 100-psi and may be equipped with
pressure-restricting or pressure-reducing valves which may or may not be
properly set. They need to pre-fire plan the buildings to learn how each
building standpipe system was designed.
rick matsuda
city of dallas
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
Brad Casterline
Sent: Wednesday, February 19, 2014 8:51 AM
To: [email protected]
Subject: 100 PSI requirement at top of Standpipe
Does anyone know why the technical committee settled on 100 PSI minimum
at the 2.5" hose valve?
It used to be 75 PSI, and for High Rise retrofit I have seen AHJs accept
75.
I am just curious because I think with about 60 PSI at the 2.5"
connection
to the standpipe we could get about 250 GPM at the nozzle, figuring the
Pf for the T, 2.5x0-6 nip, hose valve, and 100 feet of 2.5" hose.
A 15 psi safety factor seems reasonable, but 40 psi???
I know the F.D. might want to use a 2.5x1.5 reducer and 1.5" hose, but
with
150 GPM flowing through 100 feet of 1.5" hose the Pf in the hose alone
is about 162 PSI!
So, I don't get it, but I am likely missing some simple explanation, so
I'm asking.
thanks,
Brad Casterline, NICET IV
Fire Protection Division
FSC, Inc.
P: 913-722-3473
[email protected]
www.fsc-inc.com
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