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Thread: Only "pressure fittings" are available for 2 1/2 inch PVC

  1. #1
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    Only "pressure fittings" are available for 2 1/2 inch PVC

    Today I went looking for 22 1/2 degree elbows for 2 1/2 inch PVC drain pipe (schedule 40). I was told that such elbows would be hard to find and that fittings for 2 1/2 inch PVC are "pressure fittings". I'm curious why this convention arose. Apparently ordinary non-pressure fittings are readily available for 2 inch and 3 inch PVC drain pipe.

  2. #2
    I doubt you will easily find 2 1/2" pipe and fittings of any type, particularly DWV PVC. 2 1/2" is an oddball size, rare in steel pipe and even more rare in non-steel pipe. I've been around a lot of piping in my life, and I have only seen 2 1/2" a few times.

    For DWV pipe, 2", 4", and 6" are the most common and readily available, 1 1/2" and 3" are available but sometimes aren't as fully stocked. 2 1/2" doesn't provide enough additional flow over 2" to justify its use vs 3" (or even 4"). Most plumbers would probably choose to use only 2" and 4" for residential plumbing where they can, so as not to need to keep even more sizes and fittings on hand.
    Last edited by Andrew Seemann; 07-31-2019 at 11:04 PM.

  3. #3
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    I've never even seen 2-1/2" pipe, and I got my Plumbers license in 1975.

  4. #4
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    I wonder if he is measuring the outside of the pipe

  5. #5
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    I must be missing something here. Why wouldn't this work:

    Attached Images Attached Images
    Beranek's Law:

    It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
    L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.

  6. #6
    When trying to repair plumbing in a 150 yr old farm house, installed over several decades from various components, I was told that a particular fitting did not exist. I went through heck, pulling out the old pipe and installing a new PVC line. A week later, I stopped at a grand opening of a dedicated plumbing supply house and saw three of the fittings I was told were non-existent hanging on the wall. I no longer go to a hardware store or box store for plumbing supplies.

  7. #7
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    Quote Originally Posted by Jerome Stanek View Post
    I wonder if he is measuring the outside of the pipe
    I'm not measuring pipe at all. I'm thinking about how to how to route a 1 inch PEX water line under a slab by threading it through PVC, so the water line can be replaced (should that need arise) without jackhammering a trench through the slab - again! (This is a slab where jackhammering a trench to replace a leaking sewer line exposed the old water line, so it seems best to replace the water line while I'm at it.)

    Thinking abstractly, it seems that 2 1/2 PVC pipe would be a good size, but, as others point out, 2 1/2 PVC pipe doesn't exist, at least in my vicinity. Nevertheless, I'm curious about what theoretical fittings would exist for this theoretical pipe size.

  8. #8
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    Jan 2005
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    Baltimore, Md.
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    2 1/2" PVC electric conduit is a standard size. Since you are just using it as pathway for a water line it should work ok. 22 1/2 elbows are available for it but they will be sweeps.

  9. #9
    Quote Originally Posted by Tom M King View Post
    I've never even seen 2-1/2" pipe, and I got my Plumbers license in 1975.
    It's an odd duck. You feel like your eyes are playing tricks on you when you see it; too small for 3" but too big for 2". We had a few fittings of it at the water research lab I worked at. They probably needed it for a specific flow or something. There and some ancient steam boiler are the only places I remember seeing it used, at least for fluid/steam. I could see it used for PVC electrical conduit more often.

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