Swing arm in sandy soil

Discussion in 'Irrigation' started by F6Hawk, May 29, 2005.

  1. F6Hawk

    F6Hawk LawnSite Member
    Messages: 195

    Here's my plan so far:

    1" class 200 from a 3/4" service thru a 1" meter with BFP built-in (city says that is all that is necessary). Mainline & all laterals will be 1" CL200.

    I have read about funny pipe on here, and see that it is easy to use, but my neighbor has more than one rotor that has migrated, and he swears it is because of the funny pipe they used on his system.

    1) Should I go with 3/4" PVC w/4 Marlex ells for a swing arm on the rotors, or do you recommend the funny pipe?

    2) I was planning on using funny pipe on the pop-ups. I saw a neat coupler today, it is a 1" PVC coupler with a barb coming off in a "Y" instead of 90°. Would this work fine for the funny pipe, or is it better to go with a 1X1X1/2 SST?

    3) I see that funny pipe is 1/2", but rotors like the 5000+ & the I-20's have 3/4" inlets. Any reason for that? The cheaper rotors (SA42, SA32, Toros, Orbit, etc) all seem to have 1/2" inlets.

    4) Since I have varied elevations, I was leaning strongly towards the I-20s, or perhaps the 5000+ with SAM, but adding the SAM feature seems to take the price over the I-20s. Which would you recommend?

    Thanks for the help!
  2. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    The Meter has a BFP in it, or theres one after it? Here many new houses already have BFP's installed after the meter, but its not regulation yet.

    I Tamp every head down really good with the butt end of my shovel. If you don't, and your in really sandy (or muddy) soil, the head can drift up a bit. The bottom line is that funny pipe is excellent, you just need to make sure you tamp it in good. You shouldn't be able to pull the head out of the ground by hand if its properly backfilled.

    Funny Pipe. I use a 1/2" threaded to 1/2" barbed fitting (either in a 90, or a straight configuration depending on the heads location), on the sprinker line side, and a marlex streel el and a marlex 90 degree barbed fitting under the sprinkler head.

    The street el gives me one more axis of motion.

    I prefer threaded Tee's with marlex fitting, but either would work in a pinch.

    3/4" inlets on those heads are so the screw on nicely to 3/4" risers...Thats my guess.

    Just use 3/4" marlex fittings.

    You should only need to use a few SAM heads. Usually the last head in the line, or the lowest head. At the most you might need 1-2 SAM heads per zone.

    You could just install regular heads, and then take note of which ones have a drainback problem, and swap out SAM internals for them.
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,764

    Don't take that to the bank. The city may be voicing a practical opinion that a working backflow preventer at the meter will protect their supply. But there is such a thing as a construction code. Part of the construction code will be a plumbing code. That code looks at a structure, and strives to protect it and its occupants from harm. That is done by way of a backflow preventer in the sprinkler system plumbing. On flat ground, or when the house is higher then the surroundings, a pressure vacuum breaker will do the trick.

    As for head stability, if you were in extremely soft soil conditions, you could look for 'support flanges' for the sprinkler heads, which I suspect are stocked by just about nobody. (and may have ceased to be manufactured by now) You could also look for some rocks. (stocked in almost every place)
  4. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    I ran into support flanges on a call once. All they managed to do is make it take a year longer for the turf to cover the head.
  5. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,764

    I refer to an underground flange, never intended to be visible. They can (with a good swing joint connection) make a head very hard to move or knock loose. I think Toro once offered them, but I don't see them in a catalog I just peeked at.
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,764

  7. F6Hawk

    F6Hawk LawnSite Member
    Messages: 195

    Well, I found nothing there specifically, but I did find an email address and sent them an email asking about permits, BFPs, etc. Hopefully I can get an answer next week on this.

    As per the website:

    "The State Building Code applies to the following:
    State Buildings and Construction
    Schools (Public and Private)
    Motion Picture Theaters"

    Even though lots of drama happens in my home, I can't quite classify it as a Theater. And since I don't pay a nightly lodging rate... well, you get the picture! :rolleyes:

    Thanks for the link, WB!
  8. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,764

    I didn't open the pdf file because my computer 'was busy' but a google search, or an old-fashioned visit to your local library might turn up something. Your state might use the SBCC for their construction code. There are other regional codes in use, like the BOCA code, and they may use some other plumbing code, like the National Standard Plumbing Code. (which, despite the name, is not the nationwide standard) If a PVB, at a height of at least a foot above the highest pipe or sprinkler it feeds, will work in your system, you should then be in compliance with present or future codes. Installing it now makes sense.
  9. jerryrwm

    jerryrwm LawnSite Bronze Member
    Messages: 1,274

    The BFP on the meter you refer to is probably a dual check, and is installed to give the public water supply some modicum of saftey from individual homes. It is not however considered a proper backflow device for hazardous conditions which irrigation systems fall under.
  10. F6Hawk

    F6Hawk LawnSite Member
    Messages: 195

    Thanks for the input & ideas!

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