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1

Tuesday, September 5th 2017, 12:57pm

Reposting, hopefully with an image--Where to put the reducer?

I'm running a household irrigation pump from a lake. The suction line is 2 inches and the the pump inlet is 1.5 inches. I have very limited space in which to make that last 90 degree turn and also reduce the line. Which of the two arrangements shown in this side-view diagram would be the best for reducing any cavitation? Both have 5xd distance between the last turn or reduction and the inlet, but option A has a concentric reducer and a large radius 1.5 inch elbow while B has an eccentric reducer and 2" street elbow. The 2 inch pipe is coming up vertically from the ground, so I'm thinking the concentric reducer is okay for option A.

image

This post has been edited 4 times, last edit by "bobanderson" (Sep 7th 2017, 11:36am)


Wet_Boots

Supreme Member

Posts: 5,135

Location: Metro NYC

2

Tuesday, September 5th 2017, 3:48pm

facebook images don't generally work - we have been recommending tinypic for hosting images to post to these forums, but they might be having problems - try googling "free image host" and try one of the options you get. In any event, from just the words, I would think in terms of a 1-1/2 nipple on the inlet, threaded or glued into a 1-1/2 elbow, and from that point you connect the dots to your 2-inch pipe. The idea is to avoid too much trapped air in the suction line.

3

Thursday, September 7th 2017, 11:44am

Link fixed! hopefully this will give a better idea of the issue.

Wet_Boots

Supreme Member

Posts: 5,135

Location: Metro NYC

4

Thursday, September 7th 2017, 1:07pm

"A" is more uniform, especially if you have room for the sweep elbow. Unless your flows are close to the capacity of the pump, you don't have to worry too much about suction plumbing. Most of the layout advice applies to higher flows.

5

Thursday, September 7th 2017, 3:08pm

The problem is that the output is less than I need or expected based on the pump (1 HP Flint & Waling CJ1018101). I can get 35 gpm but only about 35 psi, which isn't enough to get all the sprinklers in my most distant circuit to work. Nor is there enough pressure to run the self-cleaning feature of my intake strainer. I was hoping that I could improve inflow and get better outflow.

Wet_Boots

Supreme Member

Posts: 5,135

Location: Metro NYC

6

Friday, September 8th 2017, 7:19am

You need to change the flow on your sprinkler zones. 35 gpm is a lot to expect from a 1 HP pump. The CJ101 is something you would be operating nearer to 20 gpm, in order to get the output pressures that would justify choosing a multistage centrifugal pump.

If the pump curve is showing, you will see the 100 foot mark on the output curve is at less than 30 gpm. 100 feet equals 43 psi, but that is not output pressure, since you have to account for the height of suction lift and friction losses in strainers and check/foot valves. 27 gpm at 40 psi might be more realistic, and that's before you have to subtract for the strainer self-cleaning.

This post has been edited 2 times, last edit by "Wet_Boots" (Sep 8th 2017, 7:27am)


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