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Advanced Member

Posts: 229

Location: USA


Tuesday, January 27th 2004, 10:40am

dripman, you never mentioned what brand of drip you are laying down. What type is it? And what is your psi and flow at point of connection?


Supreme Member


Tuesday, March 2nd 2004, 6:56am

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">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.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

It sounds like this comment may have already been discussed via emails, but just in case, I figured I'd discuss this in the forum.

These statements are false, mainly about the pressure being the same at both ends of the hose.
The pressure will only be the same at both ends of the pipe if no water is flowing. Once you start making the water flow, there will be friction losses as the water "rubs" against the side of the hose. This friction loss results in a drop in water pressure along the length of the hose.

So the bottom line reason you will see "rules" of drip irrigation design say something like "no more that 200' of hose and no more than 150pgh of emmiters per circut" is to make sure these friction losses stay low enough that you don't have a huge difference in pressure from the first emmiter to the last emmiter.

You will get different "rules" from different sources because they are all trying to find simple ways to explain how to build a drip irrigation system without forcing you earn an engineering degree in fluid dynamics.


Advanced Member

Posts: 53

Location: USA


Tuesday, March 2nd 2004, 1:58pm

I have installed a few drip systems and found that the Rainbird xerigation control zone kit works very good. It is designed for drip systems and includes the recommended filter(very important).


New Member

Posts: 6

Location: USA


Thursday, April 8th 2004, 11:21am

Hi, It has been a while and I have been busy setting up my system. I have learned friction loss is not as big a deal in drip irrigation (as Dr. Pete pointed out earlier) since you must reduce pressure to keep from popping off the emitters from the main and sublines. I'm not real sure the guy who took me to task on my naive pressure statement above really knows too much about drip irrigation. I think he is a sprinkler guy where friction is a big concern.

Altitude from the water source I think has more of an impact on pressure variation in low pressure drip. As far as distance check out the link above at Nebraska it addresses many of these questions. The length you can run is much much longer even if you go up another 1/4" in diameter say from 1/2" to 3/4" the carrying capacity of the system dramatically increases from 150 ft to well over 300.

Take Care, Dripman


Supreme Member

Posts: 372

Location: USA


Monday, April 12th 2004, 5:04am

Thanks for the info.


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