I pull water from a ditch to irrigate my lawn, and my pump has been surging recently, but only on 4 of 6 zones; for 2 of the zones, there is no surging and the heads are at full pressure. I also changed the valves on the 4 surging zones, but that didn't help. I'm at a total loss. Any suggestions?
Surging Pump
- Thread starter dennisc
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Surging while "pulling" water means you have a suction leak. Usually at the threads where it screws into the pump.
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Bob NH
In the Trades
Surging can also be caused by operating a pump in the wrong part of the range.
Some centrifugal pumps have a characteristic in the flow range between 0 and 20 percent of the design flow where the head (pressure) is a little greater at a low flow than it is at zero flow. That can cause a condition where the GPM/Head characteristic for the combined pump and downstream system is not sharply defined and the flow will oscillate over a range of flow.
If that is the problem it can be solved by operating the pump in the range where there is a significant down-slope in the head vs. GPM curve. Also, that usually puts you in the range of maximum efficiency. The point of maximum efficiency is often where the head is 70 to 80 percent of shutoff head.
I suggest you try operating the offending zones at higher flows. You can simulate that by replacing one head with a valve that you can open when the pump is surging. Opening the valve to permit higher flow will probably solve the problem. You can then fix the problem by putting higher flow heads, or more heads, on that zone.
Some centrifugal pumps have a characteristic in the flow range between 0 and 20 percent of the design flow where the head (pressure) is a little greater at a low flow than it is at zero flow. That can cause a condition where the GPM/Head characteristic for the combined pump and downstream system is not sharply defined and the flow will oscillate over a range of flow.
If that is the problem it can be solved by operating the pump in the range where there is a significant down-slope in the head vs. GPM curve. Also, that usually puts you in the range of maximum efficiency. The point of maximum efficiency is often where the head is 70 to 80 percent of shutoff head.
I suggest you try operating the offending zones at higher flows. You can simulate that by replacing one head with a valve that you can open when the pump is surging. Opening the valve to permit higher flow will probably solve the problem. You can then fix the problem by putting higher flow heads, or more heads, on that zone.
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