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Help with sprinkler design

ctc_01

Starting Member

Posts: 1

1

Friday, May 2nd 2014, 7:20pm

Help with sprinkler design

Need some help on designing a sprinkler system on a well. I am planning on upgrading to a 1hp 20gpm @50psi well pump. I am not sure what size pipe I need to run from the well tank to the back flow and from the back flow to the vlv boxes. If I use 1 1/4" poly its 20' to the back flow. From there it would be roughly 80' to the first vlv box. If i assume the pump can put put 16/17gpm @ 50psi at the back flow then using 1 1/4" poly 80' would produce roughly 1.7gpm loss? From there i could run my first 5 Hunter I20s on 1" poly and adjust flow rate to 14/15GPM? Then run 1 1/4" poly from the first vlv box to a second vlv box 20'/30 away that would run 4 heads and continue the 1 1/4" poly another 20'/30ft to the last vlvl box with 4/5 more heads? I would 1" poly for all the lateral lines to my heads. I wish I could figure out how to insert a picture.

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

2

Saturday, May 3rd 2014, 9:53am

You could also consider upping the main size to 1-1/2 inch, and just about eliminating pressure loss in the main. The price of this upgrade won't be all that high.

rencast

New Member

Posts: 2

3

Saturday, May 3rd 2014, 2:06pm

Sorry, I cant activate or use my crtc_01 account and I can't activate this account. So you would suggest 1 1/2" from the well tank to the back flow, then 1 1/2" to the vlvl boxes where I would reduce down to 1" for all of my vlvs and lateral runs? Thanks

Wet_Boots

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Posts: 4,102

Location: Metro NYC

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Sunday, May 4th 2014, 7:47pm

If you effectively zero out mainline pressure losses with the upsized main line, you gain some pressure for the zones, which comes in handy.

rencast

New Member

Posts: 2

5

Thursday, May 8th 2014, 6:03am

Quoted from "Wet_Boots"

If you effectively zero out mainline pressure losses with the upsized main line, you gain some pressure for the zones, which comes in handy.
Thanks. When I look at the charts for pipe size and psi loss 1 1/4" and 1/12" aren't much different. Since my well main line is 1 1/4" I will probably up the sprinkler to 1 1/2" to get the full gpm and psi from the pipe. I will have to reduce down to 1" at the vlvs and then run 1" laterals to the heads, 7 heads @ 2.5gpm for a total of 17.5gpmGPM @ 50psi. If it works this way I should be able to adjust the nozzles and get the well pump to run constantly at the 50psi and 17GPM.
Thanks

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

6

Thursday, May 8th 2014, 10:25am

If you can locate your mainline in the center of the string of zones, then you can split the zone valve output into two of more 1-inch laterals, and nearly zero out the losses in the laterals.

The more losses you can eliminate, the higher the head pressures can be, given a set pressure range on the pump controls.

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