(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 9 of 9

Thread: Design Help

Hybrid View

  1. #1

    Default Design Help

    Hi, I'm designig a Sprinkler system that fits a low pressure water system. My water pipe before my meter is 1 inch after the meter it's 1/2 inch. Now I want to design my system with a 1 inch main line and 1 1/4 inch lateral lines(Cheaper, and Complies with City Municipal Code). According to irrigation websites 1 1/4 inch poly pipe should give me 32 GPM and I plan on installing 12 sprinkler heads most of them running at 1.89 GPM. Can this be done and will it run effectively extra GPM is no problem to me this is just an estimate.

  2. #2
    Well Driller, pump installer, engineer pitless's Avatar
    Join Date
    Jan 2008
    Location
    Nebraska
    Posts
    27

    Default

    An 1 1/4" line may supply 32 gpm if the line is short. Your restriction will be the 1" inch meter and 1" if the line to your house is short most of your restriction will be in the meter.

    Plan on you have about 10pgm. You should be able to have 5-6 sprinlkers per station. Make sure you increase the size of the water line coming from you meter to 1" or 1 1/4" and you should be fine.

  3. #3
    In the Trades Bob NH's Avatar
    Join Date
    Oct 2005
    Location
    New Hampshire
    Posts
    3,307

    Default

    Quote Originally Posted by IceTreay View Post
    Hi, I'm designig a Sprinkler system that fits a low pressure water system. My water pipe before my meter is 1 inch after the meter it's 1/2 inch. Now I want to design my system with a 1 inch main line and 1 1/4 inch lateral lines(Cheaper, and Complies with City Municipal Code). According to irrigation websites 1 1/4 inch poly pipe should give me 32 GPM and I plan on installing 12 sprinkler heads most of them running at 1.89 GPM. Can this be done and will it run effectively extra GPM is no problem to me this is just an estimate.
    I don't think the system can work as you have described it.

    Since you are the "designer" of the system, YOU are responsible for determining requirements and the capability of the source.

    Design consists of developing a concept, and then analyzing the design concept to see if it will work. If it doesn't work, you need to change something about the design.

    What is total GPM for the maximum-flow irrigation zone? 12 heads at 1.89 GPM per head is about 22.68 GPM.

    What pressure do you need for the heads? Your main and laterals will have some pressure loss. Add that to the head pressure requirements.

    NOTE: What is the rationale for putting 1 1/4" laterals on a 1" main? Seems bass-ackward.

    Now, MEASURE the pressure that can be delivered to the main line through the meter and the line feeding the MAIN from the meter while MEASURING the maximum flow demand.

    Based on what you have told us (1/2" line on the output side of the meter; 12 heads at 1.89 GPM per head; low pressure water system) the chance that you will be able to deliver the required flow is somewhere between slim and none.

    IF your tests show that the supply won't deliver the flow and pressure that you need, then you must increase the supply or reduce the demand by reducing the number or flow rate of the sprinkler heads. That is called "iterating the design". After you come up with a new design, you analyze that new design to see if it will work.

    You say this is only for an estimate. The fact that is is "just an estimate" will not mean much if you build it and all of the sprinkler heads just dribble out onto the grass.

  4. #4
    In the Trades Gary Swart's Avatar
    Join Date
    Sep 2004
    Location
    Yakima WA
    Posts
    7,245

    Default

    Have you discussed your project with your local irrigation supply houses? The ones in my area have design experts that will design your system to work properly with the given limitations of water supply, pressure, and other factors. And, it's a free service with the understanding that you will buy all of your pipe and supplies from them. This may be just a local thing, but it would be worth looking into.

  5. #5
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    Location
    San Diego
    Posts
    9,001

    Default

    The limiting factors are that 1" pipe , which will probalby provide 25+ GPM, and the METER itself. You said you had one inch pipe, but is the meter actually a 1" meter? May not be, as most places charge install and base fees based on meter size, and a 3/4 or even 5/8 meter is more common. This would limit you to much less than 20 gpm

  6. #6
    In the Trades Bob NH's Avatar
    Join Date
    Oct 2005
    Location
    New Hampshire
    Posts
    3,307

    Default

    Quote Originally Posted by IceTreay View Post
    My water pipe before my meter is 1 inch after the meter it's 1/2 inch. . . .
    The 1/2" pipe is the limiting factor, unless you go all the way back to the meter with bigger pipe.

  7. #7
    Sprinkler Guy Wet_Boots's Avatar
    Join Date
    Mar 2007
    Location
    Metro NYC
    Posts
    798

    Default

    The OP needs to supply more info. What's the location? Where is the meter located? What is the pressure at the meter? How large a property?

  8. #8
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    Location
    San Diego
    Posts
    9,001

    Default

    Quote Originally Posted by Bob NH View Post
    The 1/2" pipe is the limiting factor, unless you go all the way back to the meter with bigger pipe.
    I might be misreading; but I thought he meant he would start right at the meter, not using any of the 1/2 to feed the sprinklers. Naturally, if any part of it came through 1/2" pipe, that would be very limiting.

  9. #9
    Porky Cutter,MGWC Porky's Avatar
    Join Date
    Jan 2008
    Location
    Virginia Beach, VA
    Posts
    727

    Default The first problem is not Flow!

    Most water suppliers will require an expensive "Back Flow Preventer" before the sprinkler system.

    The 1/2" meter and the 1" line before everything is the next problem.

    I suggest you go to your local irrigation supply house for assistance. You may search http://www.johndeerelandscapes.com for a supplier in you area. These people will assist you with the proper design. I don't recommend that you go to Lowes or Home Depot as they don't usually have qualified designers.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •