SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

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?

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.

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

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

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