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Thread: Old captive air tank mystery

  1. #1

    Default Old captive air tank mystery

    It's a mystery to me. I pulled vinyl bladder out of a Kenmore "Captive Air Water Tank". [What a job! My wife saw me pulling and pulling on it on the garage floor, and finally asked " Is it a girl or a boy?"
    I thought I could weld 3 more outlets on it and create a 36 gallon buffer tank for an oversized boiler. I may be dumb.
    A. There is a solid dome shape 4 to 5 inches BELOW domed top. What IS IT! I got the bladder OUY. That is, a yardstick measures that much difference between inside and outside.. Gonna be hard to pipe this thing.

    B. There is a hard black coating in there. Is that some tar- like corrosion protection? Granted, it's 10 degrees here and a lot of things are hard. [That vinyl lining was a bear.] If it is tar-like, isn't it doubtful I can store 200 degree hot water in this cold water tank.? And circulate ir through my Taco 007?

    C. Who made it. Who knows stuff? Sta-Rite makes Craftsman tanks for Sears. But the tech on call did not recognize if they had made this one. "Model 390.291601". 30 plus gallons or so by geometrics. I saw a '390.291...501 on the web labeled "Sears Best ' and alike in every respect down to the patent number , Pat. 3802464.
    Got any ideas who made it and what its little guts are made of?
    Thank you,
    Joe Walbran

  2. #2
    Previous member
    Join Date
    Jul 2005
    Riverview, Fl.


    If Sta Rite made the tank, the bladder was doomed to a short life. I'm not sure what your plans are for welding more fittings on the tank, but I don't think that tank was designed with boiler use in mind.

    I would throw the whole thing away like I have done to thousands of them over the years.

    I changed one bladder. One time. I will never do it again. I don't want to even remember the experience let alone discuss it.


  3. #3

    Default Maybe, just maybe

    Hi Bob the pump/tank guru. Thanks for responding.
    Well the tank [I'm calling it a Sta-rite] is rated to 500 PSI and my humble boiler runs at 15 to 20 PSI.
    And the steel is welded up nicely. So that aspect is ok.

    I put a propane torch to the mystery lining. It is NOT tar like. Glad for that. Its more like a rubber sprayed on stuff. It sort of powders when rubbbed between fingers. Now I have to figure out why I cannot measure full depth from port to dome top..
    As the bladder is gone, what is up there in the dome? Sagged coating? Seems to even for that.

    Any idea.? joe

  4. #4

    Default Mystery solved

    The patent # on the pump tank proved to me at least, and then to the tech at Con-aire--Sta-rite, to our satisfaction that the tank was theirs.
    In fact the tech was really amiable, and said she too had delivered one of those vinyl bladders out of a tank. Hey, a hands on person!

    But, no, they did not line their tanks furthur with tar or rubber or anything. The inexplicable thick black lining, and the 4 to 5 inches of it at the top was a mystery.

    Hmmm, it IS cold here. I stood the tank upside down and rammed a pipe down into the dome . Something gave way. The black turned white!...it was all ice!
    I had purchased this at an unheated warehouse for salvage stuff. It had recently come out of a teardown. It has not felt the summer sun yet.
    End of tale. joe

  5. #5
    Previous member
    Join Date
    Jul 2005
    Riverview, Fl.


    Ok, so now I know where the term "Black Ice" came from. The black would be sulphur.

    I'm not sure where you got the idea that the tank is rated for 500 lbs, but all bladder tanks I am aware of are rated to a max of 125 lbs. No more.



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