Calculating pressure in a pumped pipeline
Calculating pressure in a pumped pipeline
(OP)
If I am pumping a tank of water up to a free outlet (lagoon) I was wondering if I am calculating the pressure in the pipeline correctly.
based on the selected pump curve I figure out the operating point for that pump with the system. For this example say it is 300 GPM @ 30' of total head the pump needs to handle.
would the pressure in the pipe simply be [(30')(62.4 lbs/cu.ft.)]/144 = 13 psi?
Thanks,
based on the selected pump curve I figure out the operating point for that pump with the system. For this example say it is 300 GPM @ 30' of total head the pump needs to handle.
would the pressure in the pipe simply be [(30')(62.4 lbs/cu.ft.)]/144 = 13 psi?
Thanks,





RE: Calculating pressure in a pumped pipeline
RE: Calculating pressure in a pumped pipeline
The 30-feet of static head should be the difference from the bottom of the storage tank (say 3-feet off the bottom) to the maximum water elevation in the lagoon. You also have to add the flow generated headloss (if any) in the suction and discharge piping.
The pressure in the pump discharge will be the difference of the elevation in the lagoon minus the elevation of the pump plus the pressure from the flow generated headloss between the pump and the pipe discharge point. This pressure should be less than the design head pressure of the pump because it does not include the suction lift (if any) nor the pressure from the flow generated headloss between the pump and the suction.
You can find some flow calculators to determine the pressure drop in the piping at:
http://irrigation.wsu.edu/Content/Calculators/Gene...
RE: Calculating pressure in a pumped pipeline
RE: Calculating pressure in a pumped pipeline
RE: Calculating pressure in a pumped pipeline
But the pressure in the pipe will depend on the elevation where the pressure is taken.
RE: Calculating pressure in a pumped pipeline
Pump is at elev. 100.00
discharge at elev. 125.00
Static head = 25'
dynamic losses is computed to be 5'
total head loss is 30'.
It is probably something simple that I am missing here. Is there a different formula I should be using to calculate pressure?
RE: Calculating pressure in a pumped pipeline
Peter Smart
HydroCAD Software
www.hydrocad.net
RE: Calculating pressure in a pumped pipeline
Static head is the elevation of the lagoon surface minus the elevation of the supply tank surface (or the HGL of the supply pipeline pressure), assuming the pipeline profile doesn't exceed either. Add your dynamic head to static head defined this way to get your total head. Select a pump to overcome the total head at your desired flow rate. Then worry about the pump elevation and suction losses to find out if you have sufficient NPSHA.
RE: Calculating pressure in a pumped pipeline
RE: Calculating pressure in a pumped pipeline
RE: Calculating pressure in a pumped pipeline
RE: Calculating pressure in a pumped pipeline