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Regulating pressure

Discussion in 'Irrigation' started by turfman59, Jan 13, 2003.

  1. turfman59

    turfman59 LawnSite Senior Member
    Posts: 801

    I did an install last year that looking back on was very strange.
    The client was a very educated individual and an metalurgy engineer, he was very much on top of the project most of the time but did not interfere with the work being done in a timely fashion. His main concern was that his pressure be regulated ( at the pressure tank at 50 psi.) so that the pump would not catch up and cycle off and on he did not want more than 4 heads per zone and did not care about even precip rate. working with this criteria we had to install 4.7 gpm nozzles in the RB 5000's. he told me that the well was very expensive around 6000.00 dollars it was down 230 ft and had 25 ft of water standing in the pipe from the well drillers log. the pump was a 2 hp 230 volt pump. Question? would there have been another way of regulating the pressure than at the sprinkler heads with this method. I started out using nozzles that were even precip but had to abandon because of well cycling.
    You could actually see the stream pulsing when it turned on and off
  2. devildog

    devildog LawnSite Senior Member
    from sc
    Posts: 270

  3. HBFOXJr

    HBFOXJr LawnSite Bronze Member
    Posts: 1,712

    So if he was so smart, why didn't he use the well log and the pump curve from the manufacturer to select the useable gpm at the psi range he wanted to be in? Then you could have designed the system properly with matched nozzles for the most part.

    Or since he had the pump installed why didn't he find out ahead of time about how many gpm would be needed to build an irrigations system and select the appropriate pump?

    Or why didn't you talk to the driller, pump manufacturer, distributor etc about what this well and pump would produce before taking on this client and job? You were the professional in charge, right?
  4. turfman59

    turfman59 LawnSite Senior Member
    Posts: 801

    I did call Waldron Well Drilling a 35 year reputable Driller and they said that 9 months ago they had 18 gpm at 40 psi and 14 gallons per minute at 50 psi . I set up a test with 4 sprinklers on a 1.25 main direct to a t the plumber installed and the heads were throwing a little over 40 ft with a 4 gallon a minute nozzle and it was operating at that time at 40- 44 psi no cycling. Once the sytem was installed it seemed to be a whole different system. I am serious when I say that I would consider going back and tieing another head on each zone and cut it from a 5 zone system to a 4 but I am afraid something else would happen negatively, I did not say the owner was SMART I said he was educated, big difference, and If was educated I would not be asking this question on this forum. How many bruises does I guy have to take here before I am initiated into the club? Did I say the wrong word like Sideline or on the side once to many times in my last post's. Beleive me when I say you cant embarrase me, I've been beat up by professionals before.:blush:
  5. devildog

    devildog LawnSite Senior Member
    from sc
    Posts: 270



    I have had through expeirences that customers and future clients have considered installing there own systems, If you are well versed on the ( Techie Crap ) your able to eliminate there ideas of being able to do it themselves, In the last 4 years of doing this as a sideline I have noticed clients that have an education BA's Mba" doctorates ask very technical questions and are also concerned about the natural resources that they are using. That is when you are able to shine if you know and are able to explain the benefits of professional installation. 01-13-2003 08:38 AM


    Originally posted by devildog
    I could not state it better and will add these thoughts:

    6) Stay away from the "techie crap" in your bid and conversations with potential customers (the ones who have never had a system). Focusing on this (water use, head to head coverage, ETV rates, etc.) will drive too many away, cost is the principal concern for first-timers (and for many in their second or third homes). If you listen, then ask the probing questions about what they want, you will bid the job accurately.

    7) Its just my opinion AND experience, but most of those who do come at you with all the "techie crap" questions, are a nuisance, and we add % to the bid (AND its always paid off).

    Post your questions here: http://www.pump-zone.com …………!
  6. turfman59

    turfman59 LawnSite Senior Member
    Posts: 801

    Devil Dog Thank you for your post and site direction, this particular client had installed his last system by himself, If I follow your comments to the letter about dodging techie questions in this market i will eliminate 60% of my future clientel. A bunch of cheap SOB's that think if your doing it they can too! Wait a minute thats how I got into this game..LOL
  7. SWD

    SWD LawnSite Senior Member
    Posts: 989

    The easiest wat to completely stop pressure cycling with-in your irrigation system is with a cycle stop valve.
    I can't recall the website right know but do a search for cycle stop valves and you should find it.
    I just wish I had these valves on some of my larger capacity systems. I didn't find out about them until a few months ago.
  8. HBFOXJr

    HBFOXJr LawnSite Bronze Member
    Posts: 1,712

    No where in the original post did you say you had talked to the well driller. It was about what the client wanted and how you responded to his requests. Therefore my response. It particularly was meant as a warning shot over the heads of others that enter into irrigation uneducated prior to starting, inexperienced and not giving a hoot that irrigation is about enineeering.

    Do not take this as a high brow attitude, or I'm better than you. I can't stress enough that one must know irrigation and not exceed their capabilities. Of course this means you can grow professionally, but each time a step is taken you must be sure before the deal is consumated that what you are entering into is correctly designed and engineered. How do you know when to ask questions? Anytime you think of attempting to do something you haven't had prior experience with questions should be raised. This can be before you design or after you design but before you price and present the project.

    In this case it didn't pose a big problem to you but it is an example of how things can go wrong. If they go wrong they can cost you money and maybe reputation. So it's important to be right the first time.

    As for what went wrong I can only speculate and walk out on a limb, but here it is. My hunch is that you picked the nozzle gallonage and pressure rating based on on the 50 psi or less he wanted to hold the pump at. Therefore with the direct connect test it was ok because the nozzle pressure was pretty close to pressure reading at the tank.

    The dynamics changed once you added in main footage, lateral footage, backflow, zone valves etc. It's pretty common for losses to be in the 10 psi range +/- between tank and head in an average job like this.

    So an example is the RB 5000 rotor 4.0 nozzle does 3.86 gpm @35 psi at the nozzle vs. 4.46 @45 psi at the nozzle. Thats .6 gpm diff x 4 heads = 2.4 gpm less in the real world system vs flow test, hence the cycling.

    Just a guess though.
  9. turfman59

    turfman59 LawnSite Senior Member
    Posts: 801

    I am not kidding there are times when I show up to do the feild test and the prop owner wont even let me in the freaking basement to look at the pressure guage while I am running the hose bibs outside, or after I have project completed and am just curious what the dynamic or working pressure is.
    My resolution is to purchase a peizo guage and a working pressure guage to do site calculations,

    Question: am i heading in the right direction with these two purchases. I am told that the piezo is for monitoring rotor pressure and the working pressure guage is for calculating friction loss between the water meter and the point of connection.

    Regards, Bruce
  10. HBFOXJr

    HBFOXJr LawnSite Bronze Member
    Posts: 1,712

    I've never had a problem getting in the basement. Just cry, whine, stomp your feet like I do and they'll let ya right in. Serious, I have no problems. You don' start with may I. If they ask where do you want tostart you tell them the basement or craswlspace or wherever the water supply is located. Are they going to say I don't want you in my basement? If so tell them you must see the water source to properlly acertain the available water supply to the system. And someone is gouing to have to go there to determine what plumbing is required and perhaps what it will cost. I have an arrangement with 2 plumbers to do a more or less standard hookup for a fixed fee unseen. Conditions are a handful of fittings, less than 1- 20' stick of 3/4 or 1" copper and a fairly short and easy shot out the wall. Sometimes I add more for them if it isn't standard and other times if a pain I have them go out and price it for the owner separately. They supply a full flow ball valve and I supply the PVB.

    I have the piezo and never use it. Of course I have a regular gauge to screw on hose bibb. I rarely, rarely, rarely do a flow test. Everything has to be an unknown to be bother doing a flow test. The only thing I care about is static pressure on a city water system and the appropriate pipe type, distance and waer meter size. Available flow and working pressure can be calulated.

    If it is a well I want to know what pump and how deep it is hanging. I use the manufacturers curve only. You will ususally find a label on the tank or pump control box with the pump model. Model is important followed by HP. HP alone is not enough.

    The best performace check you can do is to thread a gauge into the test **** on the out bound side of the backflow. N o need to leave it, just log the numbers for your records.

    I always put the water source info on my contracts so to be able to defend my work if ever necessary in the future or for maintenance records. They consist of service line length, material and size plus meter size if city water or make, model and horsepower of pump and well or pump depth if known by the service company or driller. I don't enter this in the computer but every job has a folder where the contract is stored for reference.

    Sometimes if not intimately familiar with a particular pump I may not quote the job at the time of appt. Or I may not specify the amount of zones or max gpm of system. Or I may use gpm numbers on the low side and if I find out pump info before I do the job I will build accordingly. Even if I have to go from 1" main to 1.25" the cost is not significant and I'll drop zone(s) and maybe controller size.

    You have to stress if necessary, the client is buying an engineered "system" not product count. Of course head count maybe somewhat relevant at times. Zone count isn't, due to the fact so many guys have no clue how to design a system, calculate available supply and maximize the supply to the system. We still have fools here that take a presure test on a well just like city water and they and the prospective client think it means something.

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