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dripman

New Member

Posts: 6

Location: USA

1

Tuesday, January 6th 2004, 8:56am

General Drip Irrigation Information

I've got about 3 acres of trees scrubs and a veggi garden. Everything is spread out. I read that you cannot use more than 200 ft of 1/2" pipe and it's got to be 160 PSI poly. I've read other pamphlets that contradict that: like the Ortho book on sprinklers and drip says you can go way over 200 ft.?? Well I have some circuits that would be 200 ft or more longer than that - so should I run 3/4" to the valve for each circuit? This is for drip only no turf and no preexisting system. Is there a particularly good drip irrigation book with some rules of thumb on pipe diameters to run for various circuit lengths you know about?

drpete3

Supreme Member

Posts: 375

Location: USA

2

Wednesday, January 7th 2004, 4:54am

The 200 ft issue is an issue of flow. You lose flow the longer the run is. I dont know alot aboput drip irrigation but I think the basic principle is slow delivery of water direcly to the roots therefore less water watse. I think it would be fine to do it 100% 1/2" but 3/4 is only slightly more money and if you think flow or gallons per min is going to be a problem then do the 3/4". The flow issue for you depends on how many emmitters you will have per circuit. Hope this helps but remember I have limited knowledge of drip systems.
Thanks,

Pete

dripman

New Member

Posts: 6

Location: USA

3

Wednesday, January 7th 2004, 9:21am

You are right on target with the purpose of drip irrigation. It is a low pressure slow delivery system that is more efficient than sprinklers on trees and scrubs (of no use on turf). I guess I am not on board concerning flow. That is, if you turn the water on on a hose no matter what length it is - it has to come out (at the same pressure) at the other end. So unless you are using many emitters (drippers) on the line, the pressure is the same at both ends. So if you calculate the gph flow and it it is not maxed out for your line why does it matter how long the line is[?] Maybe I missed that calculus equation in school.

I just want to be sure that the plants at the end of the respective circuit lines get enough water. I guess most guys on here are sprinkler system users and not drip eh? I think the controllers and the valves are the same for both drip and sprinklers. What is a good controller and valve combo? - don't need the Rolls Royse model- just a pretty good one with a good track record. I'll need 6 to 8 circuits available.

Thanks for the response.


Rays Sprinklers

Supreme Member

Posts: 493

Location: USA

4

Wednesday, January 7th 2004, 10:10am

Hey,
You are right about the gph etc. The way it works though if you have 300' with 100 emitters dripping the concern is that the last line wont have enough water. I have one question thou to solve your problem....is the 1/2" your talking about to the valves or the actual drip lines. I have been using the 2400T Valves by irritrol for years and never once had a call back on them! They are one of the leading valves. The controller i recomemnd for you is the Hunter SRC...one of the best controlers on the market. Please respond and let me knwo
Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers

dripman

New Member

Posts: 6

Location: USA

5

Wednesday, January 7th 2004, 10:55am

Hey Ray,

Right now nothing is in the ground, so I can go 3/4" to the main valves and then 1/2" for the drip lines. I'm concerned about going 1/2" poly all the way because of pressure spikes you guys talk about in your emails. However, with installation of a pressure reducer that is required for drip irrigation (so you dont blow the emitters off the pipe), I'm not sure that is a real concern. I'm renting a trencher or poly pipe puller soon to install. I do pay attention to expert advice and I really appreciate yours on valves and controllers. Would you go 160psi on the poly pipe for this system or is that over-kill[?][:)]

Thanks for the help, John the Do It Your Self Dripman

drpete3

Supreme Member

Posts: 375

Location: USA

6

Thursday, January 8th 2004, 7:28am

The reason for the loss is due to friction of the fluid passing through the pipe. I think with drip irrigation this is probably negligable due to thefact that you wont be pushing 10 gallons per min through the 1/2" pipe. The fricion becomes a problem as the distance increses and as the diameter of the pipe decreases. See this link for further info http://www.sprinklerwarehouse.com/LawnCare/frctn_ls.pdf
Thanks,

Pete

dripman

New Member

Posts: 6

Location: USA

7

Thursday, January 8th 2004, 12:38pm

Pete,
The table was very helpful on friction's effect on water flow, I appreciate you sending the link.

Still waiting to hear back from Ray on solving my problem and answering my pipe question on 'is 160 PSI poly really needed'. I'm going with the valve and controller products Ray recommended unless another expert has a recommendation.
Thanks again

Rays Sprinklers

Supreme Member

Posts: 493

Location: USA

8

Friday, January 9th 2004, 1:13pm

For the runs with the emmitters you only have 15 psi in the lines, so yeah its overkill....as far as your main lines to your valves, you cannot use poly because once poly is put under pressure it POPS!! As far as the valves and the controller those are the best ones on the market today so definatly use them!
Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers

dripman

New Member

Posts: 6

Location: USA

9

Wednesday, January 14th 2004, 6:34am

Ray and Dr Pete,
I appreciate the information. Just in case someone else is inclined to do drip irrigation check out this link http://ianrpubs.unl.edu/irrigation/g525.htm It is a University of Nebraska release that pretty well answers most questions about pressure and system capacity. Not much on specific product brands and pipe friction. That's where you guys were a big help. Thanks!! John

Rays Sprinklers

Supreme Member

Posts: 493

Location: USA

10

Friday, January 16th 2004, 6:32am

any time .... glad we could help!
Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers

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