New System

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tinyman

Active Member

Posts: 7

Location: USA

Friday, June 15th 2007, 12:15pm

New System

I am installing a new system myself. I live in Alaska and there are very few irrigation proffessionals up here so I'm winging it on my own. My first topic is for drip line irrigaton, will 3/4" poly work for supply line if I have under 20 emmitters running off it? Any reccomendations for brands of emmitters, connectors, etc.? Is it better to use multiple connectors for small areas with 3 or 4 shrubs to water or do the single connector with multiple outlets work okay? My PSI is 65-70, do I need to regulate that for the driplines?
My second is for spray head zones. I am having trouble figuring how many sprays I can put on a 1" line. I want to put 8 heads on each zone since I need a total of 16 heads, most of them 12' radius or less, will this work. SprinklerWarehouse doesn't exactly describe each head's specs very well. I haven't checked my flow rate yet but I'm sure it is very good. Do "Tees" in the line reduce the capacity very much? Are there any sprays that cover rectangular areas that work well? Thanks for your help in advance and I'm sure I'll have more questions to follow.

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HooKooDooKu

Supreme Member

Posts: 683

Monday, June 18th 2007, 5:08am

Whoa, lots of questions in such a small post.
www.irrigationtutorials.com
That's your starting point for learning how to do irrigation. Yes it's a lot of reading, and some of it can be a bit confusing. But my suggestion for getting started is to read through this tutorial and then come back and ask questions... one at a time.

In the mean time, I'll answer the question about pressure and drip line.
All drip irrigation (I'm familer with) requires low pressure. I would say that 25-30pis is ideal with 50psi being an absolute maximum. The princpal reason is because most drip irrigation installs use barbed punched in emmitters or other components. Hi pressures can literally pop those barbed fitting out. Most drip irrigation systems will be designed to connect to a garden hose, so the press regulator with the drip irrigation system's name on it will usually have threads to fit a garden hose spickot. If you are installing a system that will be controlled from irrigation valves, you can get regulators you can install up-stream or down stream from the valve. I used a 30psi PVC regulator I installed just upstream from the 4 drip irrigattion circuits I installed with my system.

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huntMT

Active Member

Posts: 7

Monday, June 18th 2007, 3:16pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">My second is for spray head zones. I am having trouble figuring how many sprays I can put on a 1" line.<hr height="1" noshade id="quote"></blockquote id="quote">

The Hunter design guide http://www.hunterindustries.com/Resources/Design/design_guide.html on page 6 recommends a max flow of 13 gpm for 1 inch poly or Sch 40 PVC and a max of 16 gpm for Class 200 PVC. This should allow you to figure the maximum spray heads per line or zone based on the gpm of the spray heads.

Once you know gallons per line or zone, you need to figure the pressure at that flow rate at the sprayer heads. Static pressure of 65-70 is basically at 0 gpm. And filling a bucket to determine flow rate is gallons per minute at 0 psi. The irrigationtutorials.com have a nice section on figuring design pressure using "dry" and "wet" methods.

--
Rob

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Tom

Supreme Member

Posts: 306

Wednesday, June 20th 2007, 4:20pm

what is the size of your service line to your house? Is it copper? or another type material?

what is the size of the water meter?

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tinyman

Active Member

Posts: 7

Location: USA

Wednesday, June 20th 2007, 7:06pm

I have 1" copper with no meter. There is a pressure regulator that is set to 70 psi and a 1/2" hose bib off the line right after the regulator which is where I checked the flow. It filled the 5 gallon bucket in 16 seconds which if my calculations are right is somewhere close to 20 gpm. Since this is more flow then the poly can handle do I need a flow control before the poly to regulate that as well or do the control valves handle that?

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huntMT

Active Member

Posts: 7

Friday, June 22nd 2007, 6:18pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote"> It filled the 5 gallon bucket in 16 seconds which if my calculations are right is somewhere close to 20 gpm.<hr height="1" noshade id="quote"></blockquote id="quote">

You need to know or estimate at what pressure that 20 gpm is available and what pressure is needed at the spray head for your desired coverage area radius/diameter.

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Since this is more flow then the poly can handle do I need a flow control before the poly to regulate that as well or do the control valves handle that?<hr height="1" noshade id="quote"></blockquote id="quote">

The flow rate will be regulated by the line loss friction and the pressure available at the spray heads, so you don't need a flow controller.

--
Rob

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