We are currently trying to schedule a flow test with the fire pump locked
out of service, as a base line. Then do a test similar to what Chris said,
but with the goal being to find the flow / pressure at which the fire pump
kicks in.
Thom McMahon
Firetech, Inc.
2560 Copper Ridge Dr
Steamboat Springs, CO 80488-2136
Tel: 970-879-7952
Fax: 970-879-7926
----- Original Message -----
From: "Roland Huggins" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, April 02, 2007 11:27 AM
Subject: Re: Flow test & fire pump
Keep in mind that it is not the system demand that matters but the amount
of water that will flow at the lower pressure from what ever accumulative
orifice is open that triggers the 350 gpm pump.
Roland
On Apr 2, 2007, at 10:09 AM, Thom McMahon wrote:
What they are considering is requiring ALL designs be done to the lower
supply, without the Fire Pump running. The situation would for high
demand systems require additional fire pumps, which just seems to be an
expensive fix to a city wide problem. I propose using the lower flow to
design up to the point at which they are sure the fire pump will
activate, and then provide a second calc for all flows required above
that point.
If you start asking about current domestic demands ect. there are no
real answers nor anyone to ask. The city doesn't have a city engineer.
The guy that runs the water treatment plant and sewage plant is the only
"Water guy" they have. For years this has been called the "High
Pressure" main, which supplies the airport, and hangers at the airport.
The questions started flying when the inspectors test on the new
Terminal addition couldn't call for the fire pump to activate, and just
dribbled water. They solved the immediate problem by connecting the flow
switch to a signal transmitter to call for fire pump start, but that
still has about a 2 min. delay. Now they are looking at all the Airport
systems, because any small fire won't energize the fire pump. The
airport is located over a mile away from the fire pump.
Our project is half way between the airport and the fire pump, at a new
industrial park (Live work units) connected to the "High Pressure" main
A 4 sprinkler design for the residential portion won't start the pump,
but what about the OH II 3000 SF design area? For the first 350 Gpm the
fire pump won't be on, but for the total design demand it will. That's
why I proposed two calc's, since they tell me the "Normal pumps wouldn't
be able to supply the full 600 Gpm at 20 Psi or more, not to mention the
hose allowance.
Another screwy water system.Water tanks without the elevation to get the
water to the airport, hence they supply the pumps, fire pumps to meet
the "Emergency" demand, supplied from the same tanks. Still trying to
find the pressure settings for all the pumps on this system, and their
elevations, and the various tank elevations.
Thom McMahon
Firetech, Inc.
2560 Copper Ridge Dr
Steamboat Springs, CO 80488-2136
Tel: 970-879-7952
Fax: 970-879-7926
----- Original Message ----- From: "Roland Huggins"
<[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, April 02, 2007 10:19 AM
Subject: Re: Flow test & fire pump
Are they considering IGNORING the pump demand portion of the initial
sprinkler calc since once the fire dept hooks up, the flow is going to
exceed 350 gpm?
Roland
On Apr 1, 2007, at 12:48 PM, Thom McMahon wrote:
We have a municipal water system which operates at 48 psi most of the
time, however when the flow exceeds 350 Gpm the fire pump kicks in
and boosts the system to 145 Psi, @ 2000 gpm. Whenever a flow test is
performed the results are always based upon the fire pump flow.
As we all know most fires are contained or extinguished by one to
three heads. Obviously this isn't enough to make the fire pump kick
in.
The local Fire Chief has started to question the operation of systems
installed using the full flow of the fire pump, since even in flow
conditions over 350 Gpm it can take as long as 2 (Two) minutes for
the pump to kick in. The bigger concern as I see it is that the
design for any system up to 350 Gpm should be based upon "NO" fire
pump, with two sets of calculations one for flow up to 350, and
another for flow over 350. This way we can be sure that the sprinkler
heads will have the min. pressure and flow even if only a few go off.
The other calc should be easy to prove, as over 350 there will be a
large increase in pressure available. The caveat is that the higher
flow calculation cannot be used to reduce the pipe size below those
used for the lower calc. It is just a "Proof" calc.
Does this sound like the right approach?
No the city has no intention of changing the pump set up any time
soon.
Thom McMahon
Firetech, Inc.
2560 Copper Ridge Dr
Steamboat Springs, CO 80488-2136
Tel: 970-879-7952
Fax: 970-879-7926
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