this is how I got 28 gpm from a 3/4"

Discussion in 'Irrigation' started by turfman59, Jul 7, 2003.

  1. turfman59

    turfman59 LawnSite Senior Member
    Messages: 801

    We dug up a 3/4 inch galv line 8 ft away from a 10 inch concrete main, put in a T a gate valve a blow out after that.

    Back hoe charge for the digging 75.00 misc fittings, shut off $110.00 charge from the plumber 90.00 well under the citys charge for tapping the main of 650.00

    did a flow test right around 28 gpm

    hooked up 6 rb 5000's ss with 3 gpm and got 35 feet of throw..

    after I hook up the bfp and the meter I should be able to flow at least 20 gpm at around 45 psi

    any thoughts ?????????
  2. DanaMac

    DanaMac LawnSite Fanatic
    Messages: 13,209

    Had you already installed the pressure regulator to get the 45 psi? Or is that to follow when you do the bfp? Is that something the city would have installed with their price? Was the $75 for the backhoe with labor included? Is it all backfilled yet? Or more labor to bury it?

    Just asking ????

    Also why do you want to do it that way? I hate having to raplace the gate valve 6' in the freaking ground when it decides to not shut down completely and seep past to the bfp in the winter.
  3. turfman59

    turfman59 LawnSite Senior Member
    Messages: 801

    yes thats the labor included on the backhoe.

    the 45 psi will be theprojected dynamic pressure with the 6 heads

    the reson I did it was to shorten the irrigation time its a big lawn with a 3/4 inch galvenized service thats 75 feet long I never would have been able to do it. I would have been lucky to get 8 -9 gpm
  4. brentlent

    brentlent LawnSite Member
    Messages: 26

    I would use a 3/4" meter (min.) when planning on 20 GPM
    20 GPM = 6.5 PSI loss thru meter. You can push a meter past it's max flow, but it will wear out and have an even greater PSI loss. I've worked on a couple systems that you can hear the meter spinning over the sound of the rotors.

    What size main line are you planning on running and how many feet?

  5. jman00

    jman00 LawnSite Member
    Messages: 129

    still using 3gpm for each head. Also what is the pressure loss of 20gpm though 3/4 i dont have my book also what is the pressure loss through the meter and back flow you might not have enough pressure to run those heads. Are you going to continue your 3/4 for the main line and the laterals or make it the right size pipe for that gallonage.

    Also i am confused as to what you are doing. I read your post and are you hooking up to the city water with out tellin them. I didnt know a plumber could tap into city water. If you are not doing that then why are you using a meter if you are going in after the water meter then another meter is not needed. Either way i thought you needed a city employee to at least look at the work and get it inspected.
  6. brentlent

    brentlent LawnSite Member
    Messages: 26

    I would suggest 1.5" main. If you tried to get by with 3/4" your water velocity would be 9.4 ft/sec and you would have major water hammer and problems. Also, you would loose 15 psi for every 100 ft. of main.

    Most cities say the water line up to the meter is their property and yours after it. How did you Tee off the service (before the meter) without getting all wet?
  7. turfman59

    turfman59 LawnSite Senior Member
    Messages: 801

    This is how
    had the city shut the water off
    8 ft away from that, put a T in and a 1 1/4 main to the bfp and then the meter ( seperate ) from the house.

    using a badger meter thats capacity is 25 gpm

    all full circle heads will be 4 gpm and seperate from 1/2 turns and 1/4 turns.. full circles are space to fill in behind 1/4 trns and 1/2 turns......

    The friction loss wont be much more than 6 psi from the 3/4 inch galvanized being its only 8 ft
  8. SprinklerGuy

    SprinklerGuy LawnSite Bronze Member
    Messages: 1,778

    Wait a cut into the 3/4 line and put in a 1.25 inch mainline? And you cut a "t" fitting into this 3/4 galvanized? Then upsized the outlet of the "t" fitting to accomodate a 1.25 " mainline? Am I hearing this right???????

    Did you use a galvanized t or brass t?
    Ever hear of electrolysis?

    Good luck, glad it's not my house if the above scenario is correct.
  9. turfman59

    turfman59 LawnSite Senior Member
    Messages: 801

    The city gave me a Brass and copper fitting all compression.

    I have heard of electrolysis, Would like to expand further or just leave on an inuendo???
  10. SprinklerGuy

    SprinklerGuy LawnSite Bronze Member
    Messages: 1,778

    nope...if you understand it then no need to elaborate.

    Did you though feed the 1.25 inch main with 3/4 inch galvanized?

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