What is the max flow (gpm) in 1" poly pipe?

Discussion in 'Irrigation' started by soafone, Aug 10, 2012.

  1. soafone

    soafone LawnSite Member
    Posts: 29

    I know the 5 ft/sec. rule says you should not exceed 12 gpm when designing your zones using one inch poly pipe, but how many gpm's will a one inch poly line actually allow (max)?

    How about 3/4", and 1-1/4"... what are their max?

    I read somewhere that many designers ignore the 5'/sec. rule and design based on 10 ft/sec.
     
  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 46,449

    I have an old system blowing 50 gpm through a short (inaccessible) length of one-inch poly
     
  3. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 21,603

    Read on, the five scond rule was not invented because no one had anything better to do. I've heard of someone raising the 5' rule, but I don't agree.
     
  4. hoskm01

    hoskm01 LawnSite Fanatic
    Posts: 5,690


    Some say 7.5 fps. What's your comfort level at?

    Like Mike said, no one just pulled 5' from their arse and called it macaroni.
     
  5. txirrigation

    txirrigation LawnSite Senior Member
    from Texas
    Posts: 977

    Stay with 5fps when using plastic.

    7.5 is what people say about metal, but we use 9fps as well as most irrigators.
     
  6. CAPT Stream Rotar

    CAPT Stream Rotar LawnSite Fanatic
    Posts: 5,857

    I've put 20 gPm through 3/4 for a short run
    Then to a drip 4 way

    No clamps and 6 years later it still holds
    Posted via Mobile Device
     
  7. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 46,449

    do they even have friction loss tables for flows way beyond design guidelines
     
  8. 1idejim

    1idejim LawnSite Fanatic
    Posts: 8,840

    That question has "WHY" written all over it Morris.
    Posted via Mobile Device
     
  9. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 46,449

    It's not so much as wanting a design guide for wandering astray as it is wondering what's going on in existing systems that are using flows that are off the charts.
     
  10. 1idejim

    1idejim LawnSite Fanatic
    Posts: 8,840

    they make lots of noise and things break or wear out quicker
    Posted via Mobile Device
     

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