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bosakie

Senior Member

Posts: 16

Location: USA

1

Sunday, July 13th 2008, 2:38pm

Pipe design question

I am getting ready to install my new sprinkler irrigation system and I have a few questions before I move forward.

I have 1" coming off of my well system. I have an on-demand well and I can set the static pressure as needed. Currently the pressure is set at 80 psi and I record this reading at the faucet nearest to the main line and when I turn on a second faucet it does not drop.

I also used a 5 Gal bucket for testing GPM as well. I turned on the faucet and it took 15 seconds to fill the bucket; I did this three times with the same results. I had someone watch the pressure gauge and it did not drop from 80 PSI on any of the tests. According to my calculations this calculates to 20 gallons per minute.

My system will be segmented into 16 zones and I have the ability for additional zones as needed up to 32. I will run Schedule 40 PVC piping to all my zone manifolds.

Here are my questions,

1) after the valves, I will have 1" polly main, should I continue with 1" for the laterals or reduce to 3/4"?

2) I have the Hunter PGP adjustable Arc Rotor and will need to run a line from the lateral (5' - 7') in some areas. Can I continue with 3/4" to the heads or should I reduce to 1/2" for the line from the lateral to the sprinkler head. The sprinkler head is a 3/4" inlet.

3) Should I keep the main and laterals at 1" and off of the laterals reduce to 3/4"?

4) I also have 75 spray and bubbler heads (all will be on like type zones) and these are at 1/2" inlets. I assume it will be okay to come of the laterals (3/4 or 1") and reduce this to 1/2"?

Thank you for your assistance,

Wet_Boots

Supreme Member

Posts: 3,871

Location: Metro NYC

2

Monday, July 14th 2008, 6:06am

For poly zone piping (where is your location) you will never use 1/2-inch pipe. You might not even find the stuff at distributors. Many pros use all one-inch poly, and minimize their fittings inventory.

HooKooDooKu

Supreme Member

3

Monday, July 14th 2008, 10:29am

For poly zone piping (where is your location) you will never use 1/2-inch pipe. You might not even find the stuff at distributors. Many pros use all one-inch poly, and minimize their fittings inventory.

To help backup this statement, I recall reading at www.irrigationtutorials.com that basically 1/2" pipe has no place in lawn irrigation. The only exception I can think of would stuff for drip irrigation. Basically, there's just too much loss in pressure pushing any large quanities of water through a 1/2" pipe. After all, if the manufacturer build a spray head with a 3/4" inlet, I doubt the reason was because they expected people to feed it from 1/2" pipes.

While I can't speak of experience with poly, I know that with my work using PVC, there wasn't much of a cost difference between 1" and 3/4" (something on the order of 10%). So to maximize flexibility for future expansion and minimize any worries on pressure drops, I just stuck with 1" everywhere for lawn irrigation. The only place I used 3/4" was for lateral lines for drip irrigation circuits.

Also, www.irrigationtutorials.com tells you what's wrong with relying on a "bucket" test, so I would advise that you NOT go and design a system that assumes you actually have 20gpm available.

bosakie

Senior Member

Posts: 16

Location: USA

4

Wednesday, July 16th 2008, 8:51am

RE: Pipe design question

I am getting ready to install my new sprinkler irrigation system and I have a few questions before I move forward.

I have 1" coming off of my well system. I have an on-demand well and I can set the static pressure as needed. Currently the pressure is set at 80 psi and I record this reading at the faucet nearest to the main line and when I turn on a second faucet it does not drop.

I also used a 5 Gal bucket for testing GPM as well. I turned on the faucet and it took 15 seconds to fill the bucket; I did this three times with the same results. I had someone watch the pressure gauge and it did not drop from 80 PSI on any of the tests. According to my calculations this calculates to 20 gallons per minute.

My system will be segmented into 16 zones and I have the ability for additional zones as needed up to 32. I will run Schedule 40 PVC piping to all my zone manifolds.

Here are my questions,

1) after the valves, I will have 1" polly main, should I continue with 1" for the laterals or reduce to 3/4"?

2) I have the Hunter PGP adjustable Arc Rotor and will need to run a line from the lateral (5' - 7') in some areas. Can I continue with 3/4" to the heads or should I reduce to 1/2" for the line from the lateral to the sprinkler head. The sprinkler head is a 3/4" inlet.

3) Should I keep the main and laterals at 1" and off of the laterals reduce to 3/4"?

4) I also have 75 spray and bubbler heads (all will be on like type zones) and these are at 1/2" inlets. I assume it will be okay to come of the laterals (3/4 or 1") and reduce this to 1/2"?

Thank you for your assistance,

Good Morning,

Thanks for your resonse above. I think I will just continue with the 1" poly all the way through the system and reduce to the inlet of each head type.

I have been reading the design tutorial; the part regarding using a pump for irrigation.

First let me say that I specifically worked with my well company to install a pump that would be sufficient in using my irrigation system. I did show him my plan for landscaping and where I wanted to have my valves ...,

The tutorial assumes that every pump has a holding tank. I have a submersible on-demand water supply and the PSI can be changed - 100 PSI just by pussing the button to increase the PSI; 0 you get the water you need depending on how far the valve is open or how much water is in demand. My pump will never/has never shut off when the water valve is turned down. Item #7 in Country Bumpkin Water under wet method.

I will be trying this method this weekend.

Thanks for you support

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