I plead to the irrigation gods, gpm and flow novice nightmare

Discussion in 'Irrigation' started by Smashbrothers, May 18, 2017.

  1. Smashbrothers

    Smashbrothers LawnSite Member
    Messages: 8

    Hey gentlemen,
    I absentmindedly took a job just out of my professional skill level. One of my maintenance customers offered me the task of revising his in ground sprinkler system that has lost pressure and is no longer adequate for the lawn size. I did a pressure test and the system had 35-38psi. His original system is running 1" pcs to orbit gear drives. I opted to run 18 22sa-rvan rainbird rotary nozzles split into three stations running six sprinklers each. Will these sprinklers be able to perform at peak performance when broke down into these smaller stations? The lawn is roughly 38ft x 85ft. I know this is a vague and desperate attempt for help but I'm to the point that I'm at my last resort. Thank you
     
  2. kawasaki guy

    kawasaki guy LawnSite Fanatic
    Male, from USA
    Messages: 16,255

    So what is the GPM? :dizzy:
     
    hort101 likes this.
  3. Smashbrothers

    Smashbrothers LawnSite Member
    Messages: 8

    In my notes I have "11" but that doesnt seem to make sense now that im looking at it.
     
  4. Smashbrothers

    Smashbrothers LawnSite Member
    Messages: 8

    Sorry for the late reply :wall
     
  5. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,288

    First of all are you measuring your dynamic pressure or your static pressure.

    Choose your pressure and calculate your demand requirements for chosen heads at desired pressure.

    Calculate your available supply with no restriction and your supply at desired pressure.

    Write all of this down, stare at the numbers till they make sense or hire someone to teach you while they're doing the above.

    Pm me if you have a problem.

    Best of luck to you
     
    Smashbrothers, Mike Leary and hort101 like this.
  6. bcg

    bcg LawnSite Bronze Member
    from Tx
    Messages: 1,865

    I'd install a booster pump instead of redoing everything. The main reason being that rotary nozzles do great with low flow but still need pressure, ideally 45PSI. I'm assuming you're giving a static pressure at 35ish, in which case you're dynamic is going to be less than 30, which just isn't going to work very well.
     
    Smashbrothers and Mike Leary like this.
  7. Smashbrothers

    Smashbrothers LawnSite Member
    Messages: 8

    Ok so i forgot to mention that im in northern California if that helps at all...I just left the job and the gpm is at 8.5. I have the option to introduce a fourth valve and dedicate three or four additional sprinklers to cover the areas missed in the original plan.

    would this break my stations down in the hopes to provide the existing rotary nozzles with more pressure to divide amongst the smaller stations ?

    Also I had originally thought of a booster pump but ruled it out after consulting with a few local landscapers that advised me the cost would increase significantly.

    I orignally quoted him $3,100 to revise the existing system, parts, installation, over seed, aerate, bring in soil amendments for the red clay...does anyone have a rough estimate for the parts to inatall a medium grade booster pump, no labor?
     
  8. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,288

    I sent you a PM
     
    hort101 likes this.
  9. Smashbrothers

    Smashbrothers LawnSite Member
    Messages: 8

    Replied
     
    hort101 likes this.
  10. bcg

    bcg LawnSite Bronze Member
    from Tx
    Messages: 1,865

    The last booster pump I installed with pump, PSR, electrician, RPZ and inspection ran about $2,000, my cost.
     
    Smashbrothers and hort101 like this.

Share This Page