Another "assume" mistake.

Discussion in 'Irrigation' started by jcom, Sep 16, 2006.

  1. jcom

    jcom LawnSite Senior Member
    Messages: 791

    Designed a system with a 3/4" feed line, meter, and house line. Stubbed out to 1". Designed for 10-11 gpm.

    What a design from hell when we tried to startup. We could only get 7-8 gpm max.. Needless to say, we ended up with lot of modifying and zoning to make it all work. Went from 5 zones to 7 and still do not have "maximum" efficiency.

    We have always zoned based on pipe size and psi. (60 psi here). We have never had a problem before with this happening. Yep, older neighborhood and suspect corrosion as a possible culprit. Longest zone run is 120'.

    A flow test should have been done. Amazing how my hindsight is so accurate. Did I miss something else obvious?

  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,758

    If you ever run into a neighborhood old enough to have galvanized steel supply lines, you can get a real surprise or two. Think of it as a test of your powers of persuasion, when you explain to the customer why all your PGP's have #3 nozzles in them :p
  3. Mdirrigation

    Mdirrigation LawnSite Gold Member
    Messages: 3,793

    We always do a flow test . And design the system at 60 per cent of whats available. Why , the pressure and flow in certain areas changes as water useage increases .
  4. hoskm01

    hoskm01 LawnSite Fanatic
    Messages: 5,690

    Most customers dont have a clue that the nozzles are interchangeable and what the difference would be even if they did. They just figure the thing shoots water over the grass and they should run their system the same amount as their neighbor because the lawn next door looks good.

    As long as you get it to cover your area, your job is done. Next time, do your flow and pressure test at the end of the main where your valves will go before you design the system for the last time. This will give you the most accurate measure, rather than say, at the front of the house at the hose bib before your 150ft main line and that pressure/flow loss.

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