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The last 8 posts

Saturday, November 14th 2009, 7:34am

by Wet_Boots

Google up the information on pressure losses. By make and model of valves and backfow preventer. With "friction loss" for the pipe and fittings. The quick version is to allow for 20 psi lost from supply to sprinkler head, since a 10 psi loss is all but inevitable.

Remember, your supply measurement must be for flow and pressure combined. Not separate measurements of pressure, with no water flowing, and for flow, when you don't know what pressures are present.

Friday, November 13th 2009, 9:34am

by andy69

Frankly, with the 'requirement' that there be no heads in the middle of the lawn, I would not use MP Rotators.


Well this a not a requirement, it's a wish. Actually, I am reconsidering it with my different drawings I have made. I am more and more on a solution with a spray in the middle.

Do you know where I can get a documentation how to calculate the pressure loss, considering the pipe size and diameter, T pipe elbow, connected sprays, etc... ?

Friday, November 13th 2009, 7:04am

by Wet_Boots

It's all numbers. If you know the flow and pressure available from the supply, you can calculate the loss in pressure that each component in the system will have, and what pressure will be at each point in the system.

Frankly, with the 'requirement' that there be no heads in the middle of the lawn, I would not use MP Rotators.

Thursday, November 12th 2009, 9:00am

by andy69

Make your system connection, then measure the flow and pressure it provides. Only then will you know if your design is correct.


??
I know already the flow and pressure where the manifold for my pipes will connect (measured : 9,7 gpm - 58 to 72 PSI).
My issue is to know if with ~9,7 gallons per minute flow and 58 to 72 PSI pressure, 2 circuits are sufficient. One needs 8,25 gpm and the other 8,8 gpm. Pressure is in my opinion not an issue in my case as the sprinklers I choose need ~50 psi. On the paper, everything works fine. But I have read somewhere that I have to count on 25% flow loss. This would mean that from a 9,7 gpm there is in the reality only ~7,3 gpm available. This would mean that 2 pipe circuits are not sufficient and should consider in my design a third one.

In your opinion, is the flow loss of 25% realistic ?

:S
Well sorry for the mistake in my previous post I jump from metrics liter to gallons inches, etc.. . Of course, when I say 1800 gpm, I thought 1800 liter per hour.

Thursday, November 12th 2009, 6:53am

by Wet_Boots

Make your system connection, then measure the flow and pressure it provides. Only then will you know if your design is correct.

Wednesday, November 11th 2009, 8:30am

by andy69

It is difficult to do a picture-perfect design on an irregularly shaped property. No head in the middle of the lawn? You have a dry spot in the making. A crafty veteran would move head #8 from its current location to one where it could do a larger half-circle, and cover the center of the lawn.


Hi Wet_Boots,

Thanks a lot for your comment. Yes, I am aware about the dry spot. I don't want to have a spray in the middle of the lawn but I didn't have the idea about a 180 - 30 feet head for #8. Actualy, regarding the sun exposure, it make more sense even if I don't move it from its current place. And I could change the #12 and reduce its circle. Thanks :thumbsup:

What do you think about the GPM of each circuit against the GPM I have (~1800 a circuit vs 2200). This is ~20% of loss and I have read somewhere you have to count on 25% of loss. Do you think I am too short and should consider 3 circuits ?

Wednesday, November 11th 2009, 7:59am

by Wet_Boots

It is difficult to do a picture-perfect design on an irregularly shaped property. No head in the middle of the lawn? You have a dry spot in the making. A crafty veteran would move head #8 from its current location to one where it could do a larger half-circle, and cover the center of the lawn.

Wednesday, November 11th 2009, 5:03am

by andy69

design irrigation - mprotator - your comments welcome

Hi there,

Heredown an irrigation plan with the datas. Is this feasable with 2 circuits or do I have to consider 3 circuits ?

Thanks for your comments about this project.

The plan can be viewed here as well :

http://img697.imageshack.us/img697/7610/print4forum.jpg