I am calcing for the system (private fire hydrant). I do not need a
hose stream ( I was told to add the 1500 as a hose stream allowance
in the Hass program [not by any Hass Rep's] to simulate 1500 gpm
flowing to the hydrant)
There is going to be a new private fire hydrant on private property.
I requsted a fire flow test for the address where the new private
fire hydrant is going. The fire flow availabilty form was:
90psi static, 82psi residual at 4657 gpm. The fire inspector wanted
the new private fire hydrant to produce a minimum of 1500 gpm @ 20psi.
George Medina Jr.
-----Original Message-----
From: Ron Greenman <rongreen...@gmail.com>
To: sprinklerforum@firesprinkler.org
Sent: Mon, Oct 18, 2010 5:29 pm
Subject: Re: Fire Hydrant Calculation Method
George,
If you're calcing for the flow at a certain residual (20 psi) and you
ave residual from a hydrant and the actual flow why do you need a
ose stream? Are you calcing the water availability or the system?
On Mon, Oct 18, 2010 at 4:01 PM, George Medina Jr <fireg...@aol.com>
wrote:
That is the formula I was looking for, Thanks.
Now to change the subject slightly, I am about to calculate a fire
hydrant
sing the Hass program. The Inspector wants a minimum of 1500gpm at
20psi. The
ydrant is a Clow 4"x4"x2½" hydrant ( I was told to just enter the
flow in the
Toggle Hose Stream' which only goes up to 1000gpm (so I tried
1000gpm just for
icks) and it gave me a warning: END HEAD FLOW CONDITION SPECIFIED
BUT NO
LOWING SPRINKLERS WERE FOUND' which would not balance out. So I used
the
ormula of K=Q/sqrt of P to get a k factor to input.
I was able to calculate with a k of 333 which only gave me 1,489
gpm. I have
one many hydrant calcs in Hydracalc and even some in HASS in the
past and can't
eem for the life of me what I am doing wrong? should I adjust the k
until I get
he flow I am looking for? That does not sound correct either. Any
advice for
his absent minded designer?
George Medina Jr.
-----Original Message-----
From: Scott A. Futrell <sco...@ffcdi.com>
To: sprinklerforum@firesprinkler.org
Sent: Mon, Oct 18, 2010 8:24 am
Subject: RE: Fire Hydrant Calculation Information
Another method, from a parasite, without determining a K-factor
first, but
sing
91 (Dave's info) for the water flow test development.
Flow at any pressure:
Q=((PS-P)/(PS-PR))0.54xQR
Where Q=flow at any given pressure
P=Pressure at which you want to know Q
PR=Residual pressure measured in test
PS=Static pressure measured in test
QR=Residual flow measured in test
Scott
-----Original Message-----
rom: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org
]
n Behalf Of David de Vries
ent: Sunday, October 17, 2010 11:08 PM
o: sprinklerforum@firesprinkler.org
ubject: Re: Fire Hydrant Calculation Information
George, you can look up NFPA 291 on NFPA's website and read all
about it. If
ou don't have a copy, go to the Codes and Standards link at www.nfpa.org
, then
alf way down the page the List of Codes and Standards link, then
NFPA 291,
hen
iew 2010 edition on line.
The gist of a hydrant flow is this: Q (flow in gpm) = 29.84 x C x D
(diameter
n inches) squared x square root of P (pitot pressure in psi). The
hydrant
oefficients for 2-1/2 inch butts are 0.90 for rounded interior
corner, 0.80
or
quare interior corner and 0.70 for an interior where the butt
extends into the
nterior of the hydrant (I have never found one of these). Read 291
if you are
lowing from a steamer port (4 inch or 4-1/2 inch), cause more
coefficents
pply. Also, if you attach a playpipe to the hydrant butt, you
should use a C
f 0.97 and the actual diamter of the tip of the playpipe.
There are two ways to determine the flow at 20 psi: graph it on
N1.85 paper
nd
xtend the flow line to 20 psi, or calculate. Either way you will
need the
low
from above), the static pressure and residual pressure. Once you
have those,
hen calculate the K for the system: K = Q / (Pstatic - Presidual)
to the 0.54
ower. You will need a scientific calculator to do that (I use a
TI-30 or
I-55). Then the flow at 20 psi: Q (at 20 psi) = K x (Pstatic - 20)
^0.54.
his whole methodology is based on Hazen Williams and assumes that
the water
istribution system charactersitics are constant (the "K") and the
variables
re
low and friction (Pstatic - Presidual).
Example: You did a hydrant flow test and measured a static pressure
of 60, a
esidual pressure of 35 with a pitot of 16 from a 2-1/2 inch rounded
interior
utt. The flow is Q = 29.84 x 0.90 x 2.5 squared x square root of 16
= 671
pm.
for your system is K = 671 / (60 - 35) ^0.54 = 118. Then your flow
at 20 psi
s Q = 118 x (60 - 20) ^0.54 = 865.
Ron and Cecil, let us know if I have been doing this the hard way
for the last
0 years and show us an easier way.
Dave
David A. de Vries, P.E., CSP
Firetech Engineering Incorporated
--- On Fri, 10/15/10, George Medina Jr <fireg...@aol.com> wrote:
From: George Medina Jr <fireg...@aol.com>
Subject: Fire Hydrant Calculation Information
To: sprinklerforum@firesprinkler.org
Date: Friday, October 15, 2010, 6:39 PM
Forum,
What is the formula to find Hydrant flows at 20 psi? ( Was that said
orrectly)
I used to have the formula set up in an excel spread sheet but lost
it during
ile transfer from old computer to new computer.
I also remember having a spreadsheet containing coefficients for the
three
ypes
f 2½" outlets. If I could be directed to the location of the
information
or if anyone has an old notebook with the following information it
would be
reatly appreciated if shared.
Thanks,
George Medina Jr.
323-278-0021
fireg...@aol.com
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--
on Greenman
nstructor
ire Protection Engineering Technology
ates Technical College
101 So. Yakima Ave.
acoma, WA 98405
rgreen...@bates.ctc.edu
http://www.bates.ctc.edu/fireprotection/
253.680.7346
53.576.9700 (cell)
Member:
FSA, SFPE, ASCET, NFPA, NFSA, AFAA, ASEE, NIBS, WSAFM, WFC
They are happy men whose natures sort with their vocations. -Francis
acon, essayist, philosopher, and statesman (1561-1626)
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