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  1. #1
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,352

    chill water in sch 40 pvc

    I was told to replace a chill water pump this weekend by my employer. Old pump was ran with welded steel pipe. New pump had an offset that would require repiping. I was told to repipe with pvc. When it came down to it, the only fittings available were some sch 80 and some sch 40. I know steel pipe would have been the best repair, but that wasn't an option here. Pump supply is 65psi. Chill water 45*. Inlet 3" ; discharge 1.5". How long should I expect this pvc to hold up? I have seen it ran like this before, but with a lot of problems (easily broken).

  2. #2
    Join Date
    Jan 2001
    Posts
    7,845
    Ive never seen schedule 40 used in a chilled water application but Ive seen plenty of schedule 80 used and it seems to hold up fine and dandy.
    YOU SHALL REAP WHAT YOU HAVE _______ SOWN

  3. #3
    Join Date
    Apr 2003
    Location
    Maple Grove, MN
    Posts
    1,301
    Go with schedule 80 if you are going with the PVC (or better yet, CPVC). How are you attaching the plastic to the steel pipe?

  4. #4
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    Why use sched 40 at all ? You're guaranteeing a massive failure.

    Pumps in a penthouse above office space ? Even if they're on the ground it needs to be done right.

  5. #5
    Join Date
    Jul 2007
    Location
    Mount Airy, MD
    Posts
    7,281
    Quote Originally Posted by Six View Post
    Why use sched 40 at all ? You're guaranteeing a massive failure.

    Pumps in a penthouse above office space ? Even if they're on the ground it needs to be done right.
    I have seen this happen a few times now, typically on a weekend, on a holiday and in the middle of night

    Usually a large building where the stairs resemble the Nile river after a failure.... Gotta love cheap

  6. #6
    Join Date
    Jun 2002
    Location
    Dacula, GA
    Posts
    12,624
    Sch 80 for sure but design for thermal expansion. lay your pipe in the ditch when temp not hot night if necessary. Bury quickly before sun & heat warp pipe. If above ground and outside you have a problem. Good luck
    "I could have ended the war in a month. I could have made North Vietnam look like a mud puddle."
    "I have little interest in streamlining government or in making it more efficient, for I mean to reduce its size. I do not undertake to promote welfare, for I propose to extend freedom. My aim is not to pass laws, but to repeal them. It is not to inaugurate new programs, but to cancel old ones that do violence to the Constitution."
    Barry Goldwater

  7. #7
    Join Date
    Jul 2007
    Location
    Mount Airy, MD
    Posts
    7,281
    The best one was a schedule 40 job for a WSHP loop, Ground loop was undersized, tower was added to aid in heat rejection.....

    ALL piping run above the main control center for ALL the power in NVA....

    Tower died, pipe melted and bad things happened

    But at least they saved on???

    Ended up putting all the WSHP's on garden hoses in and the outlet going out the windows.... Thank god for 24/7 Walmart's for extra hose when needed

  8. #8
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,352
    Quote Originally Posted by ammoniadog View Post
    Go with schedule 80 if you are going with the PVC (or better yet, CPVC). How are you attaching the plastic to the steel pipe?
    Pvc flange.

  9. #9
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,352
    Quote Originally Posted by Six View Post
    Why use sched 40 at all ? You're guaranteeing a massive failure.

    Pumps in a penthouse above office space ? Even if they're on the ground it needs to be done right.
    I wanted to get a welder on site and do it right, but I am not the one signing the checks.

  10. #10
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    I hear you.

    Sched 80 is the alternative to steel. I had a water tower piped in with sched 40 and after the water source heat pumps ran up head pressues on a hot Texas day and deformed the sched 40 pipe until it finally busred loose. and flooded a 6 story building.a

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