Zone Valves....

Discussion in 'Irrigation' started by kerdog, Mar 29, 2005.

  1. kerdog

    kerdog LawnSite Member
    Posts: 129

    Irrigation control valves-----Flow control.......or no flow control?

    When or where to use? Or why, etc.? For example, would a valve with flow control, be needed on a zone using pressure-regulated spray bodies?

    How about Hunter zone valves----

    I'm partial to Hunter, mostly because of the lower psi losses, thru the valve.
    Any comments, preferences, or suggestions on applications for these different models; (Hunter) SRV, PGV, HPV.
    I don't see much difference (minimal) between the three, cost is incremental. What separates them? Is it in the diaphrams? Or the bodies? Inquiring minds want to know.........
    Just want a better understanding of the different options/applications.
  2. YardPro

    YardPro LawnSite Gold Member
    Posts: 3,563

    i have used the srv's and NEVER had any failure's.
    i now use the mid line pgv's.

    the diaphram's are different, as well af the body. i have not noticed any flow differences.

    flow control is an option that you would use if you have a high pressure situation on the output side of the valve. This can cuase the valve not to close. This is just one application where you would use flow control.
    another is that you could use it if you have misting in a zone. you can reduce the flow, and eliminate the misting issue.
  3. Planter

    Planter LawnSite Member
    from Utah
    Posts: 214

    Hunters are a great valve. I have used some, but on residentials use Rain Bird DVF because they are also a great valve and a bit cheaper from my suppliers. I always use a flow control. They let me do a shut off if I need to and I can adjust the output. Here we will have pressure from so low you need a booster pump to the culinary one I worked on yesterday that had 120 lbs at the sprinkler hose bib.
  4. FYI
    You are not reducing the pressure of the water going through the valve when you adjust the flow control....
  5. jerryrwm

    jerryrwm LawnSite Bronze Member
    Posts: 1,274

    Would you explain that a bit further please.

    When you adjust the flow control down, you are decreasing the the opening through which the water travels, increasing the pressure loss due to friction, thereby reducing pressure as well as flow. Put a pressure guage on the upstream and downstream sides and check the readings as you adjust the flow control.

    Jerry R
  6. YardPro

    YardPro LawnSite Gold Member
    Posts: 3,563

    you're HALF right.

    you are adjusting FLOW with the flow control, BUT that WILL affect pressure. As the flow is reduced to the output of the zone there will be a pressure drop.

    if you cut the flow to below the output of the zone, you will reduce working pressure even further.

    you will affect the working pressure in the zone by altering the flow.
  7. kerdog

    kerdog LawnSite Member
    Posts: 129

    What I'm seeing here is, that by using a zone valve with flow control, it can give you some control over the dynamic pressure, to that zone. Correct? So, if you've got a little more pressure than needed (or wanted) at the heads, then a valve with flow control, could help in regulating that zone. I understand that you are controlling the flow, which would also have to affect the pressure. I envision a hose-end sprinkler, open the faucet wide open, you can water a greater area, turn it down, a smaller area.
    On the other hand, I was taught (as an example) that while using a water hose, when you put your thumb over the end of the hose, to make it spray harder or faster, the pressure is not increasing. It's the velocity, you are making it come out faster, by restricting the opening.
    I'm just trying to get a better understanding of all this, not just for me, but for anyone else, too. Sometimes, it sounds a little contradicting......


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