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Q: LawnGenie valve does not shut off in a drip irrigation system on steep slope ( Answered,   0 Comments )
Subject: LawnGenie valve does not shut off in a drip irrigation system on steep slope
Category: Family and Home > Gardening
Asked by: sandy_yago-ga
List Price: $10.00
Posted: 12 Oct 2004 13:06 PDT
Expires: 11 Nov 2004 12:06 PST
Question ID: 413835
I have a drip irrigation system installed on a steep slope. The
manufacturer of the valve (LawnGenie standard plastic green valve
bought at Home Depot) recommends that the highest place emitter should
not be more than 6 inches above the level of the valve. I have the
opposite problem - the lowest place emitter is at least 10 feet below
the level of the valve.

When the outflow line is empty (i.e. there is only air in it) the
valve operates as expected. Once the line waters and the valve shuts
off, the water continues to drip out of the emitters.

It is as if the water in the outflow line exerted a sucking effect on
the valve and it would remain open for that reason.

I called the Toro helpline but the person could not even understand
the problem. I sent an email to the company but all I got was a
boilerplate response.

My actual question is this: short of cutting up the main line and
placing the valve in level with the outflow line (which would be very
cumbersome in my situation) is there any other solution, specifically
a device that empties the line once the watering is over or some valve
that would prevent outflow under these circumstances.

TIA for your help.

Request for Question Clarification by redhoss-ga on 13 Oct 2004 08:28 PDT
I'll bet I know what your problem is and how to solve it. However, to
make sure I need to know exactly which valve you purchased. Can you
identify it from these on the Home Depot website:
  Lawn Genie
1 in. Electric Anti-Siphon Valve
Model L7010
Internet/Catalog # 162347
Store SKU # 465607
  $19.97 EA 
  Lawn Genie
3/4 in. Electric Anti-Siphon Valve
Model L7034
Internet/Catalog # 162348
Store SKU # 463809
  $15.97 EA 
  Lawn Genie
1 in. Electric In-Line Valve
Model 54004
Internet/Catalog # 162344
Store SKU # 463469
  $13.97 EA 
  Lawn Genie
3/4 in. In-Line Valve Threaded Female
Model 54048
Internet/Catalog # 162345
Store SKU # 810308
  $11.29 EA 

  Lawn Genie
RJ711B 3/4 in. Anti-Siphon Valve
Model 54000
Internet/Catalog # 162343
Store SKU # 322386

Clarification of Question by sandy_yago-ga on 15 Oct 2004 16:59 PDT
it is a Lawn Genie RJ711B 3/4 in. Anti-Siphon Valve Model 54000
Subject: Re: LawnGenie valve does not shut off in a drip irrigation system on steep slope
Answered By: redhoss-ga on 16 Oct 2004 09:32 PDT
Hello sandy_yago, I am not an expert on drip irrigation systems and
have never installed one. However, I do know something about
hydraulics. I am very surprised that the Lawn Genie experts were not
able to answer your question. At first I didn't understand what the
term "anti-siphon" meant in the valve description. I assumed that it
meant the valve prevented siphoning of water to the sprinkler heads
after the syatem shuts off. After reading some on the Lawn Genie
website I determined that I was wrong. The "anti-siphon" feature
prevents water from siphoning back into your home water system should
should there be a loss of pressure (backflow prevention). Your problem
is exactly the opposite. When the system shuts off water gravity feeds
the sprinkler heads until all water has drained from the system. Lawn
Genie does not address this problem except for telling you to not
install a sprinkler head (emitter) more than 6 inches lower than the
valve. I searched for an inline check valve to install down stream
from the Model 54000 valve and found one on the Rain Bird website:

Check Valves
Control Zone Components

Features & Benefits:

Prevents water from draining upstream of check valve or back into valve box. 
Use with a Back Flush Filter when filter is at a lower elevation than
the rest of the system.
Operating Ranges and Specifications:

Pressure: 20 to 120 psi (1,4 to 8,3 bars) 
- CV-075: 3/4" FPT x 3/4" FPT
- CV-100: 1" FPT x 1" FPT 


Rain Bird does allow for your problem and the 3/4 inch version of the
valve could be exactly what you need. The reason I say could be is
that they don't say what the opening pressure rating is for the valve.
I assume that since they show the operating range is from 20 to 120
psi that the valve will hold against 20 psi of siphoning pressure
which is plenty for your layout. I am sure that your local Rain Bird
dealer can answer that question for you and recommend another check
valve if this one is not adequate. With your 10 foot elevation
difference you need a valve rated for at least 5 psi. The check valve
needs to be mounted immediately after the Model 54000 valve with the
flow arrow pointing toward the emitter (down stream). Then when the
system shuts off the check valve will close and hold water in the line
preventing additional flow. This is good for another reason also. It
prevents a water hammer situation whan the line is dry and water
rushes in as the system comes on. I think I have covered everything,
but please ask for a clarification if I haven't.

Good luck, Redhoss
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