What size for Water Meter is good?

Discussion in 'Irrigation' started by kbcjlc, Aug 4, 2002.

  1. kbcjlc

    kbcjlc LawnSite Member
    Posts: 59

    3/4 or one inch? 3/4 will cost 635.00 and one inch will cost 735 Is it better to get one inch for more water pressure?

    Keith
     
  2. Ground Master

    Ground Master LawnSite Senior Member
    Posts: 505

    static water pressure will be the same no matter what size meter you have, dynamic pressure will of course increase.

    You will gain much greater flow and less pressure loss. i.e., Instead of designing a system based on 10 to 14 gpm's, you can design a system based on 20 to 25 gpms.
     
  3. Chuck Sinclair

    Chuck Sinclair LawnSite Senior Member
    Posts: 336

    Ground Master,

    Where do you get your gpm from, where i'm form we are taught that:

    1/2" = 6 gpm
    3/4" = 11 gpm
    1" = 16 gpm
    1 1/4" = 21 gpm
    1 1/2" = 26 gpm

    And it seems to work out about right for the systems i design

    I would spend the extra and get the 1" meter.
     
  4. Chuck, someone conservative must have taught you......me too! I would rather be wrong on our side than on the other side! I have always designed based on this:

    1/2 = 6
    3/4 = 12
    1 = 18


    Never had a problem. Then, if the pressure ever drops, and it will, you should still be okay. Pressure doesn't matter though right? Yeah Right!

    Go with the 1 inch meter, 100 bucks is nothing, you'll be better off!
     
  5. Ground Master

    Ground Master LawnSite Senior Member
    Posts: 505

    chuck- check out page 78 of the complete irrigation workbook by larry keesen
     
  6. Typically the water flow is larger through a 1 inch meter than it would be through 1 inch schedule 40, so if you want that higher flow, upsize the mainline.....and be sure to use a larger pvb....right gmaster?
     
  7. kbcjlc

    kbcjlc LawnSite Member
    Posts: 59

    what is pvb?

    Keith
     
  8. rvsuper

    rvsuper Senior Member
    Posts: 930

    Pressure Vaccum Breaker
     
  9. DanaMac

    DanaMac LawnSite Fanatic
    Posts: 13,156

    If you can pay $100 extra for the 1", do it. You may save more going that route anyway. Larger zones due to designing with more GPMs means less number of valves, pipe, and possible timer. This could decrease your materials cost on the job. And possible a little labor.
     
  10. HBFOXJr

    HBFOXJr LawnSite Bronze Member
    Posts: 1,706

    All of this is a moot point if the service line to the meter is smaller than the meter. The old week link in the chain theory.

    A 1" meter maxes out a about 50 GPM flow. The safe flow for a meter is 75% of max or about 37 GPM in this case. The other design criteria is to keep flow to a GPM that will not genreate a a presure loss through the meter greater than 10% of the static pressure.

    So at 60 psi the flow should be low enough so you loose no more than 6 psi in the meter and not exceed 75% of maximum flow.
     

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