Thursday, 17 June 2021
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Hi, I'm seeking advice from the community on how to assign the right point of connection characteristics for an irrigation system operating on a well pump. When reviewing the well pumping performance graph (see attached) the performance curve tracks pressure and flow performance across the pump's operating range.

If I am designing an irrigation system to operate on one of these pumps, what pressure and flow should I use for the point of connection?

As I understand it, the graph lists the dynamic pressure at any given flow, but Land FX wants static pressure. Does this make a difference for the program?

Thanks for your help!
Use the 150' of head. The 225' point is known as shut-off head, that is, the pump is working as hard as it can, but it can't push water higher than 225'. Or in other words, no flow after that point.
Thanks Tom,

Pinning down the variables isn't a problem. The real question is, If I use the pressure listed on the pump for any given GPM does that work for the Static pressure input in Land FX?

Example:

1.5 hp pump delivers 35 GPM @ 150 ft of head approx. Do I use the 150 ft. head less the draw down elevation as the static pressure in Land FX, or do I use the pressure listed at the 0 GPM rating on the curve as the Static pressure 225 ft. of head in this case?

Thanks for your help.
Here's my advice:

1. Get the well report, or have one done. This will describe flow, draw-down, etc. This will inform how much volume the pump can produce without sucking air, and thus your pump size.
2. Do some math. I'm sure you know that feet of head * .433 = PSI. So, based on pump curve, a 1.5 hp pump produces 35 gpm at about 65 psi (~ 150 feet of head). Good for small-medium 30 psi spray zones.
3. Based on the well's capacity, the size of your site, and the pressure required for your emission devices, choose a pump. A VFD is a good thing to have.
4. Filtration is a good idea with well water.

Good luck! Let us know what you choose. Maybe give us a little site info, too.
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