Fire Flow Analysis FIRE FLOW ANALYSIS
FOR
WILLIAMSGATE SUBDIVISION
20.27 ACRE TRACT
(VOLUME 4628, PAGE 221)
CRAWFORD BURNETT LEAGUE, A -7
MDG JOB NO. 000886-3736
COLLEGE STATION, BRAZOS COUNTY, TEXAS
JUNE 2004
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The proposed development consists of the 20.27 -acres of Phases I, II, and III of
Williamsgate Subdivision. The site is now served by a 12" DIP main that runs southwest
along Rock Prairie Road. We intend to tie into this line with 6" lines at two locations,
creating a closed loop.
A fire flow analysis was conducted in conjunction with EPANET for the four proposed
fire hydrants at Williamsgate Subdivision. Appendix B of the 2000 International Fire
Code was used to determine the required flow rates and pressures for the proposed
hydrants.
Flow data for the existing fire hydrant located at 112 Rock Prairie Road was obtained
from the City of College Station Utilities. The information for this hydrant is as follows:
Static Pressure: 79 psi
Residual Pressure: 75 psi
Flow Rate: 1300 gpm
For the analysis, a pressure of 75 psi for the Rock Prairie hydrant was used. According to
Appendix B, it must be determined if the proposed fire hydrants can hold a minimum
pressure of 20' psi.
From the gathered data on the Rock Prairie fire hydrant, the Hydraulic Grade Line (HGL)
for the hydrant was determined using the equation:
HGL =z +P /d
Where
HGL => Hydraulic Grade Line (ft)
z => Elevation (ft)
P => Pressure (psi)
d => Density (62.4 lbs /cf)
Knowing the HGL for the Rock Prairie hydrant, the HGL for every node in the network
was obtained using the calculation:
HGL = HGL, - KQ
Where
K => Head loss coefficient
Q => Flow rate (cfs)
HGL => Downstream HGL (ft)
HGL => Upstream HGL (ft)
For this calculation, it is important to start at a known HGL, and move down the network
computing the HGL in order from upstream to downstream. However, if the known HGL
is located downstream and upstream HGLs need to be determined, the calculation can be
reversed to accommodate the situation. The equation for this instance is as follows:
HGL = HGL + KQ
The head loss coefficient (K) for each pipe section is calculated using:
K = (fL) /(2 *DA
Where
f => Friction factor
L => Length of pipe (ft)
D => Diameter of pipe (ft)
A => Area of pipe (ft)
g => Gravity (32.2 ft/s
The HGL for the proposed fire hydrant was determined using this method. The pressure
at the hydrant was determined by rearranging the above equation that solved for the
HGL. Knowing the pressure, the flow rate of the hydrant can be determined using the
following equation:
Q = 29.83cDA2 *sgrt(P)
Where
Q => Flow Rate (gpm)
c => Friction Coefficient (0.7 -0.9)
D => Diameter of Outlet (in)
P => Pressure (psi)
The proposed hydrants were assumed to have an outlet diameter of 2.5 in.
Using this method for calculating the HGL at each junction, the flow rate and pressure at
the proposed hydrants were computed. Further analysis of the network was also
performed using the computer simulation program EPANET. This program can perform
time simulations of the system by entering the information for each node and pipe.
However, for the program to properly work, the known fire hydrant must be entered as a
tank rather than a valve or junction. The demand for the existing fire hydrant, as a tank,
must be enough to supply the entire network. Because of this high demand, the program
computed excessive velocities for pipes B, C, D, E, 0, and P that are faulty to this
analysis.
After completion of the analysis, it was determined that the proposed fire hydrants for
Williamsgate Subdivision, will supply adequate flow rates and pressures to the site. The
hydrants can provide a total of 3618.57 gpm while staying above the minimum pressure
requirement of 20 psi.
FIRE FLOW AND WATER REPORT
FOR
WILLIAMSGATE SUBDIVISION
20.27 ACRE TRACT
(VOLUME 4628, PAGE 221)
CRAWFORD BURNETT LEAGUE, A -7
MDG JOB NO. 000886-3736
COLLEGE STATION, BRAZOS COUNTY, TEXAS
JANUARY 2004
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A ki , 2551 Texas Ave. South, Ste. A, College Station, TX 77840
Ofc: 979.693.5359 Fax: 979.693.4243 Ema mdgcstx @yahoo.com
i
The proposed development consists of the 20.27 -acres of Phases I, II, and III of Williamsgate
Subdivision. The site will be served by a 12" DIP main that is to be installed running southwest
along Rock Prairie Road. We intend to tie into this line with 8" lines at two locations, creating a
closed loop.
A fire flow analysis was conducted in conjunction with EPANET for the four proposed fire
hydrants at Williamsgate Subdivision. The domestic water section of the Bryan /College Station
Unified Design Guideline Manual was used to determine the required flow rates and pressures for
the proposed hydrants. This manual states that fire hydrants must provide a minimum of 1,000
gallons per minute in residential areas.
Z Flow data for the existing fire hydrant located at 112 Rock Prairie Road was obtained from the
City of College Station Utilities. The information for this hydrant is as follows:
Static Pressure: 79 psi
Residual Pressure: 75 psi
Flow Rate: 1300 gpm
For the analysis, a pressure of 75 ■rding to the
Unified Design Guideline Manual, i can hold a
minimum pressure of 20 psi.
From the gathered data on the Rock GL) for the _4:7)
hydrant was determined using the eqi
HGL =z +P /d
Where
V—..
HGL => Hydraulic Grade Line (ft)
z => Elevation (ft)
P => Pressure (psi)
d => Density (62.4 lbs /cf)
Knowing the HGL for the Rock Prairie hydrant, the HGL for every node in the network was
obtained using the calculation:
HGL = HGL - KQ
Where
K => Head loss coefficient
Q => Flow rate (cfs)
HGL => Downstream HGL (ft)
HGL => Upstream HGL (ft)
For this calculation, it is important to start at a known HGL, and move down the network
computing the HGL in order from upstream to downstream. However, if the known HGL is
located downstream and upstream HGLs need to be determined, the calculation can be reversed
to accommodate the situation. The equation for this instance is as follows:
HGL = HGL + KQ
The head loss coefficient (K) for each pipe section is calculated using:
K = (fL) /(2 *DA
Where
f => Friction factor
L => Length of pipe (ft)
D => Diameter of pipe (ft)
A => Area of pipe (ft)
g => Gravity (32.2 ft/s
The HGL for the proposed fire hydrant was determined using this method. The pressure at the
hydrant was determined by rearranging the above equation that solved for the HGL. Knowing the
pressure, the flow rate of the hydrant can be determined using the following equation:
Q = 29.83cD^2 *sgrt(P)
Where
Q => Flow Rate (gpm)
c => Friction Coefficient (0.7 -0.9)
D => Diameter of Outlet (in)
P => Pressure (psi)
The proposed hydrants were assumed to have an outlet diameter of 2.5 in.
Using this method for calculating the HGL at each junction, the flow rate and pressure at the
proposed hydrants were computed. Further analysis of the network was also performed using the
computer simulation program EPANET. This program can perform time simulations of the
system by entering the information for each node and pipe. However, for the program to properly
work, the known fire hydrant must be entered as a tank rather than a valve or junction. The
demand for the existing fire hydrant, as a tank, must be enough to supply the entire network.
Because of this high demand, the program computed excessive velocities for pipes 0 and P that
are faulty to this analysis.
After completion of the analysis, it was determined that the proposed fire hydrants for
Williamsgate Subdivision will supply adequate flow rates and pressures to the site. The hydrants
can provide a total of 3,790.39 gpm while staying above the minimum pressure requirement of 20
psi. Because this water distribution line meets the fire flow criteria outlined in the Unified Design
Guideline Manual, it will sufficiently supply Williamsgate Subdivision with domestic water.
WATER & FIRE FLOW REPORT
FOR
WILLIAMSGATE SUBDIVISION
20.27 ACRE TRACT
(VOLUME 4628, PAGE 221)
CRAWFORD BURNETT LEAGUE, A -7
MDG JOB NO. 000886-3736
COLLEGE STATION, BRAZOS COUNTY, TEXAS
JUNE 2004
2551 Texas Ave. South, Ste. A, College Station, TX 77840
4 Ofc: 979.693.5359 Fax 979.693.4243 Email: mdgcstx @yahoo.com
The proposed development consists of the 20.27 -acres of Phases I, II, and III of Williamsgate
Subdivision. The site is now served by a 12" DIP main that runs southwest along Rock Prairie
Road. We intend to tie into this line with 8" lines at two locations, creating a closed loop.
A fire flow analysis was conducted in conjunction with EPANET for the four proposed fire
hydrants at Williamsgate Subdivision. The domestic water section of the Bryan /College Station
Unified Design Guideline Manual was used to determine the required flow rates and pressures for
the proposed hydrants. This manual states that fire hydrants must provide 1,500 gallons per
minute in residential areas. However, this flow may be split between two adjacent fire hydrants
within 1,000 feet of each other.
Flow data for the existing fire hydrant located at 112 Rock Prairie Road was obtained from the
City of College Station Utilities. The information for this hydrant is as follows:
Static Pressure: 79 psi
Residual Pressure: 75 psi
Flow Rate: 1300 gpm
For the analysis, a pressure of 75 psi for the Rock Prairie hydrant was used. According to the
Unified Design Guideline Manual, it must be determined if the proposed fire hydrants can hold a
minimum pressure of 20 psi.
From the gathered data on the Rock Prairie fire hydrant, the Hydraulic Grade Line (HGL) for the
hydrant was determined using the equation:
HGL = z + P/d
Where
HGL => Hydraulic Grade Line (ft)
z => Elevation (ft)
P => Pressure (psi)
d => Density (62.4 lbs /cf)
Knowing the HGL for the Rock Prairie hydrant, the HGL for every node in the network was
obtained using the calculation:
HGL = HGL - KQ
Where
K => Head loss coefficient
Q => Flow rate (cfs)
HGL => Downstream HGL (ft)
HGL => Upstream HGL (ft)
For this calculation, it is important to start at a known HGL, and move down the network
computing the HGL in order from upstream to downstream. However, if the known HGL is
located downstream and upstream HGLs need to be determined, the calculation can be reversed
to accommodate the situation. The equation for this instance is as follows:
HGL = HGL + KQ
The head loss coefficient (K) for each pipe section is calculated using:
K = (fL) /(2 *DA
Where
f => Friction factor
L => Length of pipe (ft)
D => Diameter of pipe (ft)
A => Area of pipe (ft)
g => Gravity (32.2 ft/s
The HGL for the proposed fire hydrant was determined using this method. The pressure at the
hydrant was determined by rearranging the above equation that solved for the HGL. Knowing the
pressure, the flow rate of the hydrant can be determined using the following equation:
Q = 29.83cD ^2 *sgrt(P)
Where
Q => Flow Rate (gpm)
c => Friction Coefficient (0.7 -0.9)
D => Diameter of Outlet (in)
P => Pressure (psi)
The proposed hydrants were assumed to have an outlet diameter of 2.5 in.
Using this method for calculating the HGL at each junction, the flow rate and pressure at the
proposed hydrants were computed. Further analysis of the network was also performed using the
computer simulation program EPANET. This program can perform time simulations of the
system by entering the information for each node and pipe. However, for the program to properly
work, the known fire hydrant must be entered as a tank rather than a valve or junction. The
demand for the existing fire hydrant, as a tank, must be enough to supply the entire network.
Because of this high demand, the program computed excessive velocities for pipes 0 and P that
are faulty to this analysis.
After completion of the analysis, it was determined that the proposed fire hydrants for
Williamsgate Subdivision will supply adequate flow rates and pressures to the site. The hydrants
can provide a total of 3,790.39 gpm while staying above the minimum pressure requirement of 20
psi. Because this water distribution line meets the fire flow criteria outlined in the Unified Design
Guideline Manual, it will sufficiently supply Williamsgate Subdivision with domestic water.