RPZ Minimizing Pressure Loss

Discussion in 'Irrigation' started by dypsisdean, Sep 4, 2010.

  1. dypsisdean

    dypsisdean LawnSite Member
    from Hawaii
    Messages: 38

    Only one??? :)
  2. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    You really don't have a clue .... do you? Yea ... OK dean, whatever you say :rolleyes:
  3. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,292

    well, you seem to be happy with everything about your system except you can't get ag water rates.

    your not happy with us as a whole and don't agree with our methods of application so leave the system alone and accept that your going to pay a premium for water.

    out of this thread you only produced 1 pic (we like pics) and no video (we like blond women)(brunettes and except for a couple Texas guys, red heads) and i think you just might be growing dope (why you never named a rare plant) we never got any real enjoyment from this encounter.

    there are a few people that have graced this forum with issues that they felt were unique to their state or situation and you seem to follow suite with those people. the one thing that keeps me wondering is why would a man that has been through as much schooling, spent 30 yrs, designing pools and has a tree business, be raising 3 acres of plants that are not conducive to the climate in which you live? go figure.

    yup, my opinion is if i were you i'd leave it alone :waving:
  4. dypsisdean

    dypsisdean LawnSite Member
    from Hawaii
    Messages: 38

    I was contemplating whether you really wished an answer or not. It is certainly way off the beaten track from asking about the expected performance of an RPZ.

    So just in case you really wanted to know. The area I live in is more conducive to growing the types of endangered species I am trying to preserve than most anywhere in the world. The latitude, the soil, the canopy of an existing forest, and the elevation of this cloud forest is unique. If wanting and using irrigation is the same to you as growing things where they are "not conducive to the climate," then 95% of world agriculture is in the same category. Or do you know anyone who has an extensive garden who doesn't also irrigate?

    When you have, over the course of a lifetime, collected, traded, hybridized, and purchased plants that have yet to be named, and may very well be the last known specimens of certain species, using irrigation to assure their survival doesn't seem like an unreasonable strategy - or one that you should even be concerned with.

    You asked about pics. You can check my website, dedicated to palms, which is one of the main categories of endangered genera I collect with over 2000 species at present. Here's a link to a unique photographic 3D 360º Virtual Reality tour for your pleasure.

  5. 1idejim

    1idejim LawnSite Fanatic
    Messages: 11,292

    i seem to learn something every day, you must be the dean of palms? good play of words.

    i looked at the site but was not able to get the full enjoyement of the 3D feature.

    i think that i need to modify my opinion, leave it alone or don',t the choice is yours. the information you want on rpz's is available to you online from all manufactures, the testing required to make the discission is up to you.

    i wish you luck and choose not to play any longer.............

  6. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    Hmmmm, yes. Funny thing is, I could fix his problem for a fraction of the cost he is looking at spending on a new meter that he "hopes" will offset the losses associated with the RPZ install .... and provide the added bonus of a more efficient system. But heh .... why listen to the professionals he seeks advice from?
  7. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,410

    So very much of what the OP is stating does not scan. Apparently a life in the swimming pool business doesn't do much for cognitive skills.

    First off, a 3 gpm blue PGP nozzle is only going to flow that 3 gpm at 45 psi. If the head pressures are really 15 psi or less, then those nozzles are delivering closer to 1.5 gpm ~ That means a zone of 15 such heads will be using around 22 gpm

    So if the system flow is 22 gpm, will the switch from a 3/4-inch to a 1-inch water meter compensate for installing an RPZ? No, it won't

    What other means could be employed to compensate for pressure loss? The obvious answer is to upsize the system plumbing. A 500-foot run of 1-1/4 poly pipe (iron pipe size) is going to lose over 20 psi with a flow of 22 gpm. Parallel that run with an additional 2-inch line, and you completely compensate for an RPZ

    The parallel line might still work if it were 1-1/2 or 1-1/4, but it takes brains and judgment to make that call, and I credit the OP with an insufficient quantity of either, when it comes to matters hydraulic.
  8. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    Probably closer to 2 GPM at the pressure he thinks (guesses) he is working with at the heads. This puts the flow at ~ 30 GPM.

    I could reduce his flow to ~ 18 GPM, resulting in an ~ 10 PSI/100 ft gain in pressure (assuming 30 GPM is his current flow in his 1" PE), significantly reducing the strain on the fittings and pipe by reducing the velocity to something more reasonable, AND produce superior coverage that meets or exceeds his current coverage simply by using the correct sprinkler for the application.
  9. mitchgo

    mitchgo LawnSite Silver Member
    Messages: 2,941

    I'm not arguing that point.

    Point is there is still a physical 100' elevation change. Either way he will loose 15+ psi at the top or at the bottom.
  10. dypsisdean

    dypsisdean LawnSite Member
    from Hawaii
    Messages: 38

    Thanks Wet Boots and Kiril for some useful opinions and comments. Although I still fail to find the usefulness of Wet Boots continued statements about my brains, judgement, or any flawed functionality derived from experience with swimming pool hydrodynamics.

    I had never considered a parallel supply line. So I appreciate the creativity. That is why I came here. However, to do so is out of the question. Placing anything like that underground here requires an excavator (with rock breaking pneumatic hammer) the size that runs for close to $400/hr. with the operator for about 3 days. Just pickup and delivery is $500. I'm guessing the original underground run cost close to $20,000 for the complete job after resurfacing the easement, etc.

    What I think Wet Boots and others may not be appreciating is the effect of such radical elevation deltas. He may be in a location, or hasn't had experience in laying irrigation on steep terrains. As stated and agreed upon by another member here is that there is about a 40psi pressure gain from the weight of the water in a 500 ft. 1 1/4" pipe falling 100 ft. And this is about what my observations indicate. So I will go with that.

    So here is what I have decided to do, despite my lack of judgement and mental skills.

    What hasn't been mentioned, along with several other unique nuances (because this has been hard enough to explain in detail already), is that there is additional elevation differences on the property as well. There is probably another 100 ft. difference on the property between the uppermost zones and those at the bottom. There is a 4 station manifold and controller close to the top using three of the zones. And another identical setup near the middle servicing the lower zones. In short, this means that some zones are operating at very different pressures than others. In addition, a few heads here and there have different nozzles to either increase or decrease the coverage/throw/flow because I was not able, in some cases, to place them exactly where I wished.

    What all this means is that after I install the RPZ I can "play" with the set up. I can move some heads from any zone at higher elevation (and lower pressure) and add them to a zone further down the hill with slightly higher pressure if I have a zone that is now too "weak." This would not be too difficult since everything is above ground. Or I could steal 3 or 4 heads off of each of the three zones on one manifold/controller and add them to a new 4th zone that is already available on the controller and manifold. More work (a day or two), but much less expensive than a booster pump, new meter, or parallel supply line. Or I may get lucky and find that the RPZ doesn't infringe enough to necessitate other than some very minor tweaking. If anyone is interested, I would be happy to report back.

    Thanks again for the feedback. I like to have all my bases covered and contingencies planned for before I undertake an important and potentially expensive project. Especially when dealing with a piece of equipment (an RPZ) that I had no experience with. And considering my diminished mental abilities it always helps to get advice from those with higher IQs.
    Last edited: Sep 6, 2010

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