Excessive pressure = mist spray from heads?

Discussion in 'Irrigation' started by ed2hess, Mar 15, 2008.

  1. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,329

    The system design point was 60psi and we measured 90sps so we dug and glued and started to backfill. Now(hopefully not to late) we begin to realize that the city inspectors look for excessive misty overspray. Since most of these head indicate a 30 psi rating(4" pop-ups) I assume at 90psi we got a problem. What are my best options? This is a very large system on a 4 acre lot and 2" water line around property... Some of the options I can think of are:
    1. Put a pressure control device like a Wlkens BR-4 at meter
    2. Turn down the valves...don't understand this very well
    3. Get these special heads with pressure control in them(just made aware of these by distributor). Apparently costly.
     
  2. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    My vote is option 1 on the mainline right after BFD.
     
  3. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    I would go with a Watts or Febco PRV over Wilkins as well, or at least one with a bronze top.
     
  4. hoskm01

    hoskm01 LawnSite Fanatic
    Posts: 5,690

    Absolutely a PRV over new heads. One thing to install rather than (100?)

    The pressure reducing heads are pretty cool though, maybe 2 bucks more per head, depending on what youre buying. Next time.
     
  5. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,329

    I have a lot of my back education on pressure....but what happens if you simply turn down the valve flow? The reason I ask is when doing repairs on many commericial properties I almost always find that the valves aren't wide open. I would guess they did that as a last resort to pass the inspection:confused:
     
  6. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 22,076

    Never trust anyone about psi/gpm..take the test yourself.
     
  7. hoskm01

    hoskm01 LawnSite Fanatic
    Posts: 5,690

    The flow valve resitricts just that, flow. It can compensate for high pressure by restricting the flow to the point that the drip uses the pressure faster than your small opening can put it in. Not the "correct" way to do it though.
     
  8. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 22,076

    "Resitriction" is a nice term for bogus design.
     
  9. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,329

    So will the pressure reducing device reduce the flow when we go from 95psi down to 60psi? And I assume that if pressure drops from city I would need to adjust this device?

    We took some measurements and found that pressure went from 95psi down to 80psi near the end of the line. We was getting a lot of mist. We turned the flow on valve down to 30psi and heads still popped up and no mist. I understand this is NOT the way to get rid of mist but we learned something.
     
  10. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 22,076

    Classic complaint.....prv work as long as the zones are equal. Gotta get your hydraulics together.
     

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