# Need help on submersible pump chart

Discussion in 'Pumps and Tanks Well Forum & Blog. Water is life.' started by jason robinson, May 3, 2021.

1. ### jason robinsonNew Member

Joined:
Apr 13, 2021
Location:
GA
How does I use a capacity chart for submersible well pump? I got confused looking at a "performance curve" chart vs the "capacity chart". Mainly had to do with the discharge psi on the capacity chart.

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2. ### Reach4Well-Known Member

Joined:
Sep 25, 2013
Location:
IL
140 ft of head corresponds to 60 psi, and 115 ft would be 50 psi. Let's say you wanted to use a 40/60 pressure switch. So if you take the actual number of ft to water, and add 115. Pick a pump that gives you 7 to 10 gpm (or whatever your flow wants are) at that head. So if your water was 40 ft down, look at 155 on the left axis. Tthe 1/2 hp 10 gpm pump would be good according to your chart.

Then check that the flow is still not low when you do the same thing, but add 140 to the distance to water.

Check that you get some flow with the water level down to the pump, but be content with a lower amount of water at that depth.

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4. ### jason robinsonNew Member

Joined:
Apr 13, 2021
Location:
GA
So in my calculation I get 25' (static water level), 10' (ground level to highest water point in house), 115' (50 psi, then I have to add in friction loss (no idea how to calculate friction loss. Is there at generic standard I could apply? House has 100' 1/2 cpvc, 60' 3/4, typical number of elbows and such and 60' 1" poly from well to houst.
And I guess the bottom chart just helps if you don't have someone telling you the 115 for 50 psi and 140 for 60psi values.

5. ### Reach4Well-Known Member

Joined:
Sep 25, 2013
Location:
IL
There are pressure loss calculators, but if you just use 5 psi, close enough, I would think.

Actually, for purposes of having enough water to backwash an iron filter, you could use 40 psi from the chart. 30 psi is usually enough for backwashing filters.
Bottom chart is easier for most people.

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