copper to pvc

Discussion in 'Irrigation / Sprinkler Forum' started by marley972, May 25, 2005.

  1. marley972

    marley972 New Member

    I am installing a sprinkler system and i have a copper main line running to the house from the meter. I am trying to tie pvc off of the main copper line. What is the best way to do this? And second question...I usually use 3/4 inch pipe to run off the main line for the sprinklers. Can I use 1/2 inch...and how many heads will it pop up with this water pressure? All advise appreciated!!
  2. Terry

    Terry Administrator Staff Member

    Bothell, Washington
    There are a few things you need to get,

    1) backflow prevention device off of the main.
    2) proper sizing.

    You are better off with larger pipes.

    This link should help

    Rainbird for do-it yourself home page

    You should check with the local inspectors to find out what backflow prevention devices are accepted.

    If you are going from copper to pvc, you would use a copper female adapter and thread a pvc male adapter into it. This is critical. It doesn't work the other way around.

    Male pvc fittings can go into metal female fittings, but metal male fittings should not go into plastic female fittings.
    Last edited: May 25, 2005
  3. captwally

    captwally New Member

    Please do yourself a favor and read up on this subject. This is not something that you can get help with from a forum such as this since there are SO many variables. Sure we can help on a more specific level on each issue, and I am more than willing to give you as much information as I can. Let's try to narrow a few things down:

    First, Follow Terry's advice, as it is true and good. Then, you need to find out and arm yourself with some information. I'm assuming that you are on city/community water since you mentioned a meter. Find out the pressure and GPM that you have avaliable. This will determine how many heads you can have watering your lawn per zone. You need to take friction loss into consideration in relation to pipe size. The larger the pipe size, the less the friction loss, and the longer the run, the friction loss increases. If you research this enough you will discover why sprinkler systems start out with large pipe closest to the POC (Point Of Connection) and reduce down to smaller pipe by the time you get to the last sprinkler head farthest from the POC. Each sprinkler head has a different output in GPM (Gallons Per Minute) and all this has to be taken into consideration. Do you see the need for extensive research and why us Irrigation contractors had to study for and pass a rather intensive exam? It really gets interesting when you start doing sports fields and commercial systems.

    Oh, and just a quick explanation as to why Terry's advice in PVC to Copper advice is so true and critical: Plastic is more pliable and succeptible to fracture under stress than metal. So when tightened, a female adaptor will tend to expand and crack over time, while a male adaptor will compress and not be subject to that vulnerability.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    Unless you are cutting into the main pipe and intend to have the pipe come out of the ground somewhere, at least 12" high, install a backflow preventer, (most areas only require a pressure vacuum breaker), and then run the pipe to the valves you are doing it wrong and unsafely. We don't know what your plans are, or how the existing piping is installed, but if you are in a cold, freezing area, the vacuum breaker will have to be in a protected area.
  5. captwally

    captwally New Member

    Even up in the arctic zone a PVB can be installed outside provided you install a drain so that you can empty it of water prior to the first hard freeze. Leave it open until spring.
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