Hyd. Pressure at PVB

Discussion in 'Irrigation' started by No Rush, Sep 9, 2010.

  1. AI Inc

    AI Inc LawnSite Fanatic
    Posts: 25,298

    That is how i WOULD DO IT. tHEN DO YOUR TIE IN AND retest it.
     
  2. AI Inc

    AI Inc LawnSite Fanatic
    Posts: 25,298

    Ok, just realized tie in is done. whats currently on the system side of the pvb?
     
  3. No Rush

    No Rush LawnSite Member
    Posts: 203

    i'll be out there today, take pictures of the gauge on both sides of the PVB, even run the water to see the pressure drop; report back this evening.
     
  4. Sprinkus

    Sprinkus LawnSite Silver Member
    Posts: 2,100

    Are you irrigating the whole park?
    Are you going to use rotors that require 50 psi to operate?
     
  5. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,324

    use maxipaws :)
     
  6. Some Sprinkler Guy

    Some Sprinkler Guy LawnSite Member
    Posts: 167

    You have learned one of the first rules of being an irrigator. DONT BELIEVE ANYTHING THE CITY (or anyone else for that matter) TELLS YOU. Check for yoself.

    Seriously, I've had to argue to the death with numerous purveyors about meter tap blockages, water leaks (mine or theirs) meter issues, meters overbilling, meters with low flow etc. I would trust nothing that they told me without verifying myself.
    Posted via Mobile Device
     
  7. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    That should be what you are testing anyhow. Dynamic pressure is the number you need to do the design.
     
  8. Inspired

    Inspired LawnSite Senior Member
    Posts: 544

    The pressures the city reports are more of a goal they shoot for or design for. Think of the city water system like a huge sprinkler system with lots of valves opening and closing all the time. Just as the operating pressure in your sprinkler system will change as valves open and close (and as things wear out, like head seals and diaframs) the operating pressure on the city water system changes.

    Never use someone else numbers, do you own measurements.

    Static pressure is a ball park figure anyway. As Kiril said, you should be thinking about dynamic or operating pressures.

    Listen to Sprinkus. Rotors with a 55psi static pressure will not work our well for you.
     
    Last edited: Sep 10, 2010
  9. mitchgo

    mitchgo LawnSite Silver Member
    Posts: 2,774

    A pvb will drop 2-5 psi from the check and internal parts inside..
    So yes you will have a different psi reading from tc# 1 vs tc#2
     
  10. No Rush

    No Rush LawnSite Member
    Posts: 203

    Update - the 1.5" irrigation meter is 518' from the 2" PVB with a 2" SCH. 40 main line connecting the two; the meter is connected to a 6' city water line most likely by 1.5" poly (that is what they use for water taps here). Now, I went out today and checked the static and dynamic water pressure at the PVB and took pictures. Here is what I got using two different gauges:
    Static 1: 66 psi
    Static 2: 68 psi
    Dynamic 1: 56 psi
    Dynamic 2: 56 psi
    While running a zone I also opened the #2 test port on the PVB and the dynamic dropped just alittle more on both gauges to 52 psi.
    Next I did all the same tests except i put the gauges on the #2 test port and the dynamic readings were lower 52 psi / 48 psi.
    Now, I have designed the new system at 55 PSI (static); have a looped sch 40 2" main line with the PVB only about 1-3 feet from the meter. The rotors i am using only require 35 PSI to operate. From the readings at 518' away I should have plenty of water available. The largest zones are only running 35 GPM a zone.

    STATIC 1.jpg

    STATIC 2.jpg

    DYNAMIC 1.jpg

    DYNAMIC 2.jpg
     

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