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Page 1 of 1 L-20-143-Water-Meter-Justification-AWWA 07-Sep-2021
Date: 7 Sept 2021
Re: Stanford Senior Living
WATER METER JUSTIFICATION
(AWWA)
As required by the local potable water utility, Integrated Mechanical is providing justification for the water
meter sizing. The American Water Works Association (AWWA) has published the Manual of Water
Supply Practices – M22 with suggested guidelines on water meter and service sizing. Integrated
Mechanical has followed the guideline and the results are attached.
The Civil plans, by Northern Engineering, indicates a new 2” tap and meter. 5' downstream of the meter a
3” service will run into the building.
An incoming static pressure of 80 psi has been measured at the site fire hydrant. Tap, meter and service
losses will leave a minimum of 41 psi at the water service entry inside the building. Due to the height of
the facility a booster pump will be utilized to gain an additional 35 psi of pressure. Internal losses within
the building and the elevation loss will cost another 55 psi, leaving 20 psi at the top floor for proper water
fixture operation.
The facility will require 154 gpm of peak water flow. A 2” positive displacement meter is rated for up to
160 gpm while a turbine meter is rated for up to 190 gpm Either device will meet the facility demand.
The proposed 2" water service, tap & meter, is deemed to be acceptable by this office.
Thank you and please contact our office if you have any questions.
Respectfully,
Thomas M. Segelhorst
Professional Engineer
INTEGRATED
MECHANICAL, LLC
WSE = Water service entry
2 NPSH = Net Positive Suction Head
Lb per square
inch (psi)
Minimum pressure available at main ............................................................................................................80 Per fire flow test revceived Aug 25th 2021
2324.4 WSFU Fixture Units ~
154 GPM Flow Figure 4.2 or 4.3 ~
2 Size in Meter loss ................................................................................................................................................7
2 Size in Tap fitting loss ...........................................................................................................................................2.7
58 feet Tap to Meter Pipe Length ~
18 psi/100 Pressure drop per 100' pipe ..................................................................................................10.44
3 Size in Water Service Size ~
58 feet Water Service Pipe Length (Meter to building)~
2.8 psi/100 Pressure drop per 100' pipe ..................................................................................................1.624
12 feet Static elevation head loss ustream of WSE ........................................................................................................................................5.196
Special fixture loss - Backflow Preventer ...........................................................................................12
Special fixture loss - PRV ......................................................................................................................0
Special fixture loss - Other ......................................................................................................................0
Total overall losses and requirements (Sum lines B through H) .................................................................38.96
Pressure Available to overcome pipe friction (Line A minus Lines B to H) ................................41.04 < NPSH Available (Cannot be lower than 5, but check on pump literature)
Water Boost Pump Pressure Boost 35 < Leave at zero if no booster is installed.
Highest pressure required at fixture (setion 604.3) .............................................................................................20 < Look up plumbing fixture req
53 feet Static elevation head loss downtream of WSE ........................................................................................................................................22.949
Special fixture loss - Pressure Regulator ...................................................................................................................0
Special fixture loss - Other ......................................................................................................................0
545 feet Longest pipe run within building
50 % Add for valves and fitting
817.5 feet Total equivalent length pipe
4 feet/100'Pressure drop allowed per 100' pipe 32.7
Losses downstream of WSE -75.649
Extra pressure avaialble 0.391 < Must be greater than zero
Pipe Sizing witin
Building
SIZING OF WATER PIPING SYSTEM
AWWA MANUAL 22
1
Description
Water Service
Piping - up to
WSE