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malibu jim

Active Member


Friday, October 28th 2005, 5:02pm

Closed Circuit

I am redoing a line in our back yard that runs thru perimeter flower beds and removing a few spray heads to install quite a few Rain Drip hydro ports for a drip system. Since this system encircles most of our yard (not a real big yard) I was worried about loosing pressure at the end of the run and wondered what would happen if I T'd the line out of the valve and made a complete loop around the yard, Would this help at all, even though the supply is goverened by the flow through the valve? I've never heard of doing this, but it sounds like it might help to equalize the pressure.


Supreme Member

Posts: 5,222

Location: Metro NYC


Saturday, October 29th 2005, 1:51am

No problems with looping the line. It's more commonly a technique employed in large systems where they loop a main line that individual zones tap from.

malibu jim

Active Member


Saturday, October 29th 2005, 9:24am

What is the result of looping? Does it help equalize the pressure?


Supreme Member


Saturday, October 29th 2005, 5:52pm

by looping a line you effectively cut your pressure loss by half.


Supreme Member


Wednesday, November 2nd 2005, 10:20am

If I understand what you are trying to do, you are converting an irrigation circuit (likely using 3/4" to 1" pipe) to drip irrigation, and you're doing this in what you call "not a really bid yard".

Well if the pipe in the ground is only 3/4" and the total output of the circuit stays below 300pgh, then a 200' run of pipe would have at most about 4psi pressure difference.

So if I'm understanding right, I don't see what's the point of more pipe in the ground. The bigger issue is to ensure you don't have too much pressure comming out of the irrigation system. While I think most drip systems indicate they will handle upto 50psi, I think you really want the system to be closer to 25psi.

I've never used them, but I read that Rainbird (perhaps others) have conversion kits. These kits replace a spray head and include a pressure regulator, filter, and something to tie your drip tubing into. If you used these kits at each spot you want to tie into the circuit, the pressure inside the pipe would stay high all around the yard AND you'd get that 25psi lower pressure desired by the drip irrigation.

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