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Wednesday, May 3rd 2017, 2:23pm

Munro Pumps

Hello everyone.
I've been designing my irrigation system and have come to the point of sourcing a pump.
After accounting for all of my elevation losses, mainline losses, lateral losses, etc... I need to push about 130 ft of head.
So begins the unending search for a decent pump.... Based on the available pump curves there are not many centrifugal pumps on the market that want to push much over 100 ft of head and many of those pumps will provide little GPM at that pressure. There seems to be a big market for cheap, high GPM pumps around the $300 - $400 range for the average consumer.
There is one pump that I have located that will supposedly do the job and that is the Munro lp200B sold at Sprinkler Warehouse. I don't mind paying the premium for this pump if it delivers according to the provided curves. Actually I would be thrilled to have it if it delivers the 30 GPM at 130 ft that the data sheet promises.
Does anyone use these pumps? Can you vouch for their performance according to the curves? I'm skeptical that the numbers are inflated due to the fact that they are quite a bit better than any other centrifugal pump I can source.
Thanks in advance,
Brian

Wet_Boots

Supreme Member

Posts: 5,063

Location: Metro NYC

2

Wednesday, May 3rd 2017, 8:38pm

Don't waste your time with centrifugal pumps. Use a jet pump. Specifically, use a shallow-well jet pump. They have a design that recirculates a portion of the water in a way that increases output pressure. You get the pressure you need for a sprinkler system. You won't get 30 gpm from any of the Goulds jet pumps in the performance chart below, but you get good pressure and reliable performance. You will have an easier time designing around a lower flow, anyway, and splitting the design into more zones.


3

Thursday, May 4th 2017, 12:21pm

Hello wet boots!
I really appreciate your reply. I will start looking into the jet pumps and consider the design changes that I will need to make. This system that will cover one acre of lawn so I'm being extra cautious in design....
I would like to ask two more questions if I may.
1) I am pumping from a lake, but I do not wish to have the pump at the waters edge for various reasons. My lift will be less than 5 feet, but the run to the water is approximately 100ft. Will this pump handle this situation?
2) I have a garden and a small fruit tree orchard that I would like to irrigate utilizing drip emitters. The GPM of the jet pump is lower than the centrifugal, but still much greater than the series of 1gpm emitters I would use in a zone. My guess is that if I used them in a dedicated zone that the system would basically use my 200 feet of mainline as a pressure vessel and cycle my pump in an undesirable fashion. How would I establish a drip zone with this setup (or should I bag it and just put in sprays?)
Again, thank you so much for your response!
Brian

Wet_Boots

Supreme Member

Posts: 5,063

Location: Metro NYC

4

Thursday, May 4th 2017, 8:21pm

First, the long suction line is okay, provided it is large enough in diameter. All friction losses in the suction plumbing add up and convert to feet of water, so the pipe part of that sum should be as close to zero as practical. If you use 2-inch Sch 40 PVC for the suction line, and include a foot valve and maybe a second check valve right at the pump, you can read pump performance from the 10-foot-lift line. If your intake included a screen in the lake, enough clogging of the screen would create a pressure loss that would translate to a higher effective lift height, with pump performance reduced accordingly.

Second, you probably want to avoid drip irrigation from lake water, since it requires a filtered water supply. There are sprays, and there are bubblers you can employ for the tree watering. If you had this question with filtered water, you could swap the 1 gph emitters for specialty emitters in sizes up to 24 gph, and work out a match to the supply.

5

Friday, May 5th 2017, 8:44am

Thanks again Sir Boots!
My intention was to hook up a 2" PVC well point to the end of the 2" intake line and utilize a check valve. In your opinion, would a foot valve be a better option? There are some fancy lake intake filters available out there, but they really seem overcomplicated and expensive for what they do. It seems that a foot valve in a 5 gallon bucket with *lots* of small holes would be adequate to keep the water velocity low enough from attracting every weed in the lake.
As for filtration, I was planning on running the pump output through a 2" 150 mesh disk filter to protect my entire system and allow the use of the drip emitters, but now that I think about it, I may be dealing with cleaning a filter daily if I go that route (plus it costs some PSI). I can likely save myself a few bucks, eliminate the filter and utilize bubblers as you have wisely suggested....
Thanks again for your expert advice. It is most appreciated!!!
Brian

Wet_Boots

Supreme Member

Posts: 5,063

Location: Metro NYC

6

Friday, May 5th 2017, 10:56am

If I had one of those Goulds pumps at lakeside, I would only use a check valve at the suction intake, in large part because is makes draining a suction line much easier come cold weather. For a long suction line, there might (repeat, might) be some concern about a large column of water needing to be lifted by the pump. A check valve should have a 1/2 pound spring in it, so an extra check valve adds about 1 foot of equivalent lift. If you had more height in your suction line, it would be pretty much mandatory to have a foot valve, just to be on the safe side. {I remember a small gasoline-powered utility pump straining mightily pumping water from an old wishing well at a 20-foot lift, and the addition of a foot valve quieting that protesting engine}

For the intake screen, you might look at a VuFlow screen

SprinklerNewbie

Starting Member

7

Wednesday, June 7th 2017, 10:04pm

BOOSTER PUMP ISSUES

Thank you for taking my question. My fiend installed a GT20 2hp Goulds pump. The city line entering the pump is 75 psi. (I know it's high) But he uses it for a baseball field which sits 100ft from pump and the last zone is almost 300ft from pump. The pump also sits 5ft below ground live in a pit. It runs on 240 volts. Can this pump handle that psi 75 which is feeding it from city line? And if so, how big of pressure switch do I need ?

Quoted


Wet_Boots

Supreme Member

Posts: 5,063

Location: Metro NYC

8

Thursday, June 8th 2017, 8:14am

A standard pressure switch will handle that pump motor, but you might have to upgrade your selection of a switch in order to be able to set a cutoff point that is higher than 80 psi. The pressure rating of the pump itself is given as 125 psi on one seller's website, and the maximum output pressure of of the GT20 added to 75 psi gives you a value of less than 130 psi, so your application should be fine, as long as your pressure switch is in order, and a pressure relief valve is included.

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