150 at 1000 at the FDC is a good rule of thumb. I'd say <1% of FD's can't
achieve this. And this 1% is really in the middle of nowhere so there
probably aren't standpipes for 100's of miles. Like Cliff said these FD
pumps are variable speed so some of what we know about pumps doesn't apply.
But what Leyton said about checking with the local. Don't confuse the
supply side, well beyond us sprinkler guys concern. Now in MN we've put the
150 @ 1000 into code. I think MA did something similar, too.
This comes from NFPA standards that define fire engines. An engine must be
able to produce a boost of 150. The gpm is specified by the city (buyer).
Most common is 1000 gpm or better. Although, in some larger cities you
might find 750 gpm pumps and some real rural areas where the 1950's oil
truck was converted with a bumper mount pump might be even less. But since
your tax dollars through federal programs are transferring your wealth to
rural FD's to buy modern fire trucks these rural places are less common.
But even these 750's should be able to produce 150 @ 1000 with the aid of
the city side. The 150 also comes from basic FF training to pump into
sprinkler or standpipes at 150. I always taught start at 150 and keep going
up until the problem got better. If a sprinklered fire isn't going out at
150 will 300 do any more harm even if the system rips apart? If it ain't
controlled on FD arrival I bet there is a good chance it's a total loss no
matter what the FD does or doesn't do.
The extra from the city in these matters can be considered to account for
the friction loss in the hose between engine and the FDC. Well if you want
a logical reason why it isn't considered. The reality is there are way too
many variables to consider as a general rule of thumb and the variables
change over time with the current operations at a fire and long term when
the FD changes something for the new fad like fog nozzles. What's the flow
rate through what size and length of interior hose or combination of hoses,
what are the nozzle requirements and what's the exterior hose size, pressure
limitations and length or possibly more than one hose. 150 @ 1000 is very
conservative in real fires. These are generally sprinklered buildings so a
pan of water from the sink is enough for the hot spots. (A small
exaggeration for humor sake)
Just to follow on the volume of the supply it's rarely 1500 gpm on board.
500 gpm on board is the most common. 750 is becoming more common, but again
in the big city you can see 250's. If there are no hydrants the building is
most likely not in compliance with the fire code IFC section 508. If there
are no hydrants the FD brings the water on shuttles (tankers in the East and
tenders in the West). That's a wild time. Any FD worth their salt should
be able to maintain 1000 gpm easily. I've been part of 2000 gpm drills with
only a handful of tankers, it's not really hard. But the initial setup can
take some time and that's a function of how far you are from your
neighboring FD's.
Chris Cahill, P.E.
Fire Protection Engineer
Sentry Fire Protection, Inc.
763-658-4483
763-658-4921 fax
Email: [EMAIL PROTECTED]
Mail: P.O. Box 69
Waverly, MN 55390
Location: 4439 Hwy 12 SW
Waverly, MN 55390
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Cliff
Whitfield
Sent: Tuesday, April 10, 2007 10:45 AM
To: [email protected]
Subject: RE: Manual wet standpipes
I think the cleanest way to calc the manual standpipe is to put a separate
source (supply) at the inlet of the FDC using the 150 PSI @ 1500 GPM as your
flow test. You may need to make your test S-150; R-149.5; & F-1500 to make
your calc program work.
I believe the pumper truck will have a "variable speed" pump that can be
adjusted based on the city supply so they can actually limit the discharge
pressures accordingly. Again, I'm no expert on this, just my understanding.
Chris Cahill is an ex-fire guy so he can probably give much more info if
he's out there this AM. Steve Leyton is the standpipe guru but he may not
be in his office today either.
Cliff
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Dewayne
Martinez
Sent: Tuesday, April 10, 2007 10:36 AM
To: [email protected]
Subject: RE: Manual wet standpipes
I have always left the city pressure out but one of my designers
questioned me on it after they did a calc showing a demand over
[EMAIL PROTECTED] supplied by both the truck and city pressures. It just
looked weird on the calc to see this.
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Cliff
Whitfield
Sent: Tuesday, April 10, 2007 10:29 AM
To: [email protected]
Subject: RE: Manual wet standpipes
Dewayne,
I imagine there are some FD guys out there that will know for sure but I
would believe that you would not include any pressure from the city
water.
I believe the FD would not want to pressurize the system beyond 150 PSI
not knowing if the system components could take pressure beyond 175
since that is what most are rated.
Cliff
Fire Design, Inc.
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Dewayne
Martinez
Sent: Tuesday, April 10, 2007 10:23 AM
To: SprinklerFORUM
Subject: Manual wet standpipes
We have a discussion in our office on the correct way to calculate a
manual wet standpipe.
Our local fire department pumper trucks are set for 150PSI @ 1500 GPM
and contain a 1500 gallon tank For calculating a manual wet standpipe
back to the fire department connection, should we only use the rated
capacity of the pumper truck or are we allowed to add in the city water
pressure/flow available at the hydrant at which they hook up to? IE:
Either treat it as a stand alone fire pump off a tank or as a standard
fire pump w/ city water supply added in.
Thanks,
Dewayne
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