Hyd. Pressure at PVB

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

  1. No Rush

    No Rush LawnSite Member
    Posts: 203

    Some back ground info - I am designing an irrigation system for a park (8.62 acres); the current PVB is about 400 ft from the 1.5" meter and the line from the meter to the PVB is 2" sch. 40. The meter is coming off of a 6" city main line.

    I put two different pressure gauges on test **** one of the PVB and get 68 psi. I even tried putting a gauge on test **** two and got a close reading.

    I call the city water dept for verification of water pressure and they tell me the most pressure to that area is 55 psi.

    Am I missing something here?
     
  2. DanaMac

    DanaMac LawnSite Fanatic
    Posts: 13,156

    Did you check the stagnant pressure? :)
     
  3. No Rush

    No Rush LawnSite Member
    Posts: 203

    68 psi was the static pressure at the PVB.
     
  4. DanaMac

    DanaMac LawnSite Fanatic
    Posts: 13,156

    Stagnant, not static. Inside joke for the old timers. Nevermind.
     
  5. mitchgo

    mitchgo LawnSite Silver Member
    Posts: 2,774

    Elevation change....
     
  6. No Rush

    No Rush LawnSite Member
    Posts: 203

    ok - ok...I'll be there one day
     
  7. No Rush

    No Rush LawnSite Member
    Posts: 203

    If there is any elevation change it's not more that 1'
     
  8. mitchgo

    mitchgo LawnSite Silver Member
    Posts: 2,774

    That's a flat 400' run

    I wouldn't worry about it. Water districts can be wrong. I mean they don't even have a way to read psi at the meter ( you would think a meter could have a built in psi gauge ) Beside 68 is much better then 55

    How about the main road leading the park, any elevation change?
     
  9. Check your gauge for sure. Maybe try a second gauge. (never mind. I reread and you used two gauges) Not sure what the time of day was but try a reading during peak water usage. I know John's Dad puts a cya in on design pressure in his plans. The final pressure reading is up to the installer and adjustments need to be made accordingly. Course you may be doing the install as well. I guess if you are confident in your readings you could split the difference with the 55 and go from there. Definitely worth investigating a little more.
     
  10. No Rush

    No Rush LawnSite Member
    Posts: 203

    I have designed the system using the numbers the city told me (55psi) but, I am pushing them for verification of the water pressure in that area. So far no one from the city has been out there. I am just trying to CMA.
     

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