check valves

[cbutler]

I'm dealing with approximately 15' of elevation change from the valve to the lowest sprinkler head. Rather than installing a check valve (anti-drain valve) on every sprinkler head along the pipe (6), wouldn't it be sufficient to just install 2-3 evenly distributed along the length of the pipe (approximately 45')?

thanks

[Irrigator]

First of all I am confused:

A Check valve is a one way gate for water which won't allow water to flow backwards in the pipe.

An Anti drain valve can be a valve that will not let water out of the system that is below a certain pressure.

15' of water is about 7.5 psi.

If you are using an anti drain valve check to see what pressure it holds before opening and make sure it is at least 8psi. I think you need one for each sprinkler or the water could leak out of the unprotected ones.

[cbutler]

Sorry for the confusion, I have seen the term "check valve" and "anti-drain" valve used interchangeably on various websites, including RainBird's site. Thanks for the info about the level of pressure with 15' of elevation change. Correct me if I am wrong, but wouldn't the 7.5 psi exist only at the lowest sprinkler, and decrease as elevation change is reduced? In other words, wouldn't the pressure be significantly less at the sprinkler heads at say 5' and 10'? My thinking is that if I reduce the pressure in the system at 3 places along the line, there wouldn't be enough pressure anywhere in the line to force water out the top of a sprinkler head.

[Irrigator]

Yes, 30 ft of water is equivalent to 14.7 psi and this is proportional.

so at lower elevations you would get less pressure.

I think what you are saying sounds about right. If you are reducing the pressure after each valve then having a few in series interspersed down the line should work.

Is there a rating on the anti drain valve? This could help you decide how many you need and where to place them.

[cbutler]

I haven't purchased any yet. Home Depot and Lowes don't sell any, so I might have to buy some online. Hunter sells an adjustable product for $10 that would work perfect, but it is a little pricey.


thanks

[cbutler]

I also have a set of valves that are at a lower elevation than some of the sprinkler heads, so I get a lot of drainage at the valve once it is closed and everything in the pipes flows downhill. I am curious if it would be ok to put an anti-drain valve a foot or two off the valve to prevent the water from flowing out of the pipe? Will this negatively affect the functioning of the control valve?

thanks