Suction pumps?

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Chris

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Does anyone make a suction pump that might work for my irrigation line?

I have to cross a highway and about 200 feet of my neighbors property. He is bring difficult with things. Assuming I have check valves and properly prime the pump is it possible to get a pump that will suck eater through a couple hundred feet of pipe with maybe 5-8 feet of lift?

My original pump was going to be a three phase 220 gpm.
 
It can be done, but filling the line with water first would make priming a lot easier. The line has to be big enough so as not to cause much friction loss at the desired flow.
 
I have no problem putting in a 4 or 6 inch line, would prefer to stay away from 8 because of cost. I can put in a primer or prime off my well on my property.
 
I'm not sure. I talked to my local pump guy and gave him my requirements and that's where he came up with the 220 gpm pump which was way overkill for my needs. I wanted to go bigger than I need but in reality I won't be running a whole bunch at one time. I wanted a pump that fluctuates as demand is needed instead of just always running wide open.
 
Well at 220 gallons per minute, four inch at 200 feet doesn't add much friction and six inch has practically none. I used to sell a 5 hp self priming centrifugal that would do around 220 per minute at 0 pressure and into the mid to high 100's per minute at 30 - 40 psi. That is probably what you need. Or if you need less water, drop down to a three horse or even a two. When you get down to the two horse, you are well below 100 gpm.

As far as the pump running full bore, it doesn't care. Less water moved, less amps pulled from the motor.
 
If you buy a pump that will do say 200 gallons a minute, you're kind of stuck with that horsepower. So if you want to slow it down a lot you're still going to be turning that big motor over. As the pressure goes up and the volume goes down the amps will go down a certain amount but not like I think you'd like them too.
 
By the way you mentioned check valves, the only check valve you want is the one at the furthest end of the pipe farthest away from the pump.
 
While a long suction line will work, it can cause problems. I just had a similar system where every time the pump was shut off for a while the air in the water would rise to the top of the suction line. Then the next time the pump was called to start, it would lose prime. We moved the pump closer to the water (much shorter suction line) and the problem went away.

If you use a Cycle Stop Valve to control the pump, you can have a 240 GPM pump and use 240 GPM when needed. But the CSV will make it work down to as little as 5 GPM when smaller amounts of water are required.
 
While a long suction line will work, it can cause problems. I just had a similar system where every time the pump was shut off for a while the air in the water would rise to the top of the suction line. Then the next time the pump was called to start, it would lose prime. We moved the pump closer to the water (much shorter suction line) and the problem went away.

If you use a Cycle Stop Valve to control the pump, you can have a 240 GPM pump and use 240 GPM when needed. But the CSV will make it work down to as little as 5 GPM when smaller amounts of water are required.

Wouldn't an Air Vac fix that problem?
 
So I went down to my local pump place and they say there is no way I could put a pump that far from the water unless I had the pipe gravity feed with water to keep the prime. I was going to hire them to set the pump up but the more I look into it I don't see why I couldn't do it myself?
 
It's no problem keeping a prime if you put the check valve or the foot valve at the far end of the suction line away from the pump. This keeps the pump and the entire suction line full of water once the pump turns off.
 
Actually you want a gradual incline all the way to the pump, so air travels all the way to the pump and out. And yes you can vent the air from a long line like that if you can get the vent in the high point(s). But you will need a continuous acting air relief, as the foot valve will keep that line pressurized when the pump is off.
 

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