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Did I design my zones correctly

Lawnworks

LawnSite Fanatic
Location
usa
Alright after many hours studying irrigationtutorials.com I would like you guys to critique my zoning. I am figuring on 17gpm. I have 82psi, 1" water meter, 1" main line. I am a little weary of the 82psi... regulator? Please excuse my wiggly lines. Any info, advice is greatly appreciated.





This is another one of the back yard. Any ideas on which is better?

 

Wet_Boots

Banned
Location
metro NYC
Why is it that you are 'figuring' a flow rate, rather than making your connection and actually measuring a flow and dynamic pressure?
 

PurpHaze

LawnSite Fanatic
Location
Visalia, CA
Lawnworks said:
How do I do that?
Go here: http://www.irrigationtutorials.com/sprinkler03.htm

You CANNOT design a system without knowing what your dynamic (working pressure when water is flowing at maximum GPM) pressure and GPM (how many gallons of water per minute are flowing at the POC). Consider it your "bank account" that can't be overdrawn or nothing will work right. I've seen people do their own without measuring their "bank account" and then turn a valve on only to have zones just sputter. :p
 

jerryrwm

LawnSite Bronze Member
So how do you design an irrigation system for a project that has not been built? The ground has not been broken for the buildings, and no construction has started. How are you going to get your dynamic pressure reading then?

How do you design a system that has not been completed, but you have been given that parameters that you will have a 2" or 4" meter? Explain how you do a flow check on a 4" meter that isn't there yet, but you have to begin construction and will not have any water supply for three or four months into the project? Yes it happens - We had over 40 - 2" valves installed running between 75-90 GPM per zone in off of a 6" looped main before the meter was installed. And the system was designed to operate with four valves running at the same time.

If you understand pipe hydraulics and can do the calculations to properly size the piping in the zones, you can design and install an irrigation system that operates as designed.

Jerry
 
OP
L

Lawnworks

LawnSite Fanatic
Location
usa
PurpHaze said:
Go here: http://www.irrigationtutorials.com/sprinkler03.htm

You CANNOT design a system without knowing what your dynamic (working pressure when water is flowing at maximum GPM) pressure and GPM (how many gallons of water per minute are flowing at the POC). Consider it your "bank account" that can't be overdrawn or nothing will work right. I've seen people do their own without measuring their "bank account" and then turn a valve on only to have zones just sputter. :p
Alright, I did read that section and I am thinking 17gpms as max flow. This system would have a 55psi pressure loss, so w/ 82psi I thought I was ok. All of these zones are well under 17gpm so I should be ok, right?
 

Wet_Boots

Banned
Location
metro NYC
If you have to make a connection to supply your system, why not make it first? Then you can run flow and pressure tests. (you do have a pressure gauge, right?) This is a luxury you can indulge yourself in. You don't have to guess. You can know. Unlike the example above, where 2 inch valves were running at about half of what a 2 inch meter is generally rated for (160 gpm) a home water supply might be more or less than what you're reading from a chart. Sometimes a lot less, if the supply line is ancient or kinked. Make your connection, and then you'll know.
 
OP
L

Lawnworks

LawnSite Fanatic
Location
usa
I have not got the job yet so I can't do that yet. The spicket at the house reads 82psi. Also, I don't understand how you actually test it. That sounds like a surefire way to get it right.
 

Wet_Boots

Banned
Location
metro NYC
You have a pressure gauge with a hose bib adapter. Go and buy one if you don't have one already. There is a water meter, from which you can read a flow. That's all you need. I have a (calibrated) Toro flow-and-pressure gauge I use for evaluating water supplies. I was actually under the impression this was your own home. For a job you're selling, go ahead and overdesign it, since the important thing is getting thorough coverage. And proper backflow prevention.
 
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