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  1. #1
    Join Date
    Oct 2011
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    Norwood-ish, Adelaide
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    Default For the hydraulisists

    For those who tinker with hydraulics. This is why seals should be replaced after a while.
    IMG_0559.JPG
    This is the piston from a bit of kit that was stripped down today as there was a suspicion that it was bypassing.
    Michael

  2. #2
    Join Date
    May 2011
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    Murray Bridge S Aust.
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    Default

    Only a suspicion??? With seals like that, I'm amazed that it went!!!!!
    Thanks for the pic.
    Kryn
    To grow old is mandatory, growing up is optional.

  3. #3
    Join Date
    Jul 2016
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    Melbourne
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    Default

    What material were those seals, and how old were they?

    Pretty decomposed!

  4. #4
    Join Date
    Apr 2012
    Location
    Healesville
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    2,129

    Default

    I dont think that is an age related problem, I have replaced seals that were more than 50 yrs old that still held oil.
    I think that has had an incompatable fluid in it, the seals look as though they have become hard and brittle and broken into chunks and the o-ring looks ok.

  5. #5
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    Oct 2011
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    Default

    They were a proper hydraulic seal (probably urethane) and the cylinders were running hydraulic oil. About 15 years old as far as we can guess. The rod seal (made of similar material) was intact but did not seal very well. The pieces did not seem very resilient, so how they hardened up we don't know. It's one of those bits of equipment that does not see much use.
    Mystery...
    Michael

  6. #6
    Join Date
    Jun 2016
    Location
    Sydney
    Posts
    283

    Default Nasty

    Cheap and nasty rubber there!
    Viton is good.

    Cheers
    Roger

  7. #7
    Join Date
    Jul 2006
    Location
    Athelstone, SA 5076
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    4,255

    Default

    Quote Originally Posted by rcaffin View Post
    Viton
    Depends on what fluid/chemical etc its in contact with...If I recall correctly Viton A was the preferred material on some refrigerants/oil mixes while B was the preferred on some others while Viton was not the preferred at all on some

  8. #8
    Join Date
    Oct 2008
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    N.W.Tasmania
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    Default

    While Viton is a high performance material, earlier this year I purchased a couple of pump up pressure sprayers from Repco, after being assured that they could handle acetone. Within seconds of first using acetone in them they began misbehaving, and long story short, it was the Viton seals, which incidentally were exactly the same colour green as the seals Michael has shown. They began to swell, and by the time I returned the spray bottles a week or two later, just disintegrated when we pulled the assembly apart back at Repco's. I don't know if there is a colour code convention for identifying seal materials, but the only other time I came into contact with Viton gaskets, they were a similar colour as I recall.
    Viton or not, those seals seem not to have liked the hydraulic medium that they came into contact with, and you may have to replace them sooner or later Michael.

  9. #9
    Join Date
    Sep 2006
    Location
    Mallacoota,VIC,Australia
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    Default

    As Kryn said it's a wonder the thing worked at all.
    All The Best steran50 Stewart

    The shortest way to do many things is to do only one thing at once.

  10. #10
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    Jul 2006
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    Athelstone, SA 5076
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    [QUOTE=Ropetangler;1952362]While Viton is a high performance material,[/QUOT

    More than 6 Viton grades. A B F and some others.
    I recall

  11. #11
    Join Date
    Oct 2008
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    N.W.Tasmania
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    Default

    Thanks Eskimo, I was unaware of the different grades of Viton, I have only had limited exposure to it during my working years, but will consult Dr. Google for details sometime.

  12. #12
    Join Date
    Oct 2004
    Location
    Southern Highlands NSW
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    Default

    Just to mention about Viton, I would be very careful if it started to decompose.
    Reportedly, if it is burnt it produces a particularly nasty chemical - hydrofluoric acid.
    Advice: NEVER burn Viton.
    I don't know if decomposition without heat is also hazardous, but I wouldn't assume it's safe.
    Hydrofluoric acid burns are no laughing matter.

  13. #13
    Join Date
    Oct 2008
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    N.W.Tasmania
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    Default

    It seems thatI have much to learn about Viton, I was completely unaware of the hydrofluoric acid connection. I am however aware of the dangers of hydrofluoric acid, and as you say it is quite unpleasant stuff. I don't think that the old seals would pose much of a threat (unless burnt perhaps), as when they came out, they had lost their elasticity, and looked like a mouse had been chewing holes in them, I was amazed at the state of them as I had considered Viton to be pretty impregnable, like glass or Teflon, but acetone had cut them unlike hot water on jelly. I should add that the result was not wet or gooey in any way, more like a dead dingoes donger from The Simpson Desert. Thanks for the additional info, I will take extra care of any Viton I have to dispose of.

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