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57 DeVilbiss compressor switch question

Discussion in 'The Hokey Ass Message Board' started by b-body-bob, Oct 8, 2011.

  1. b-body-bob
    Joined: Apr 23, 2011
    Posts: 515

    b-body-bob
    Member

    My old compressor wants to run until it's over 130 PSI before shutting off on the high side. To be honest, I don't need that much pressure, and with this old equipment less pressure would be safer too. So I've got it in my head to reduce the high side pressure on the switch.

    The switch has two screw with spring adjuster gadgets. One is tall, one is short. There is a picture in the attachments. I was hoping someone here would be familiar with this kind of switch could tell me which of those adjusters to turn to affect the high side pressure, and which direction to the nut turns to reduce the pressure?

    Also thought there might be some interest in the cool old compressor so I posted more than just the switch photo.

    Thanks for any help,
     

    Attached Files:

  2. shoprat
    Joined: Dec 23, 2006
    Posts: 1,109

    shoprat
    Member Emeritus
    from Orange, CA

    I'd personnaly leave it alone I think. If that was the way it was designed to work.
    I broke my sw and had to buy a new one on mine. Not cheap. JMO
    Just regulate it down.
     
  3. Dangerous Dan
    Joined: Jul 10, 2011
    Posts: 390

    Dangerous Dan
    Member
    from Graham Wa.

    Just back off on the big , usually 7/16, that will lower your cut in and cut out pressure together without changing the differential. The small one changes the range between cut in and cut out ( differential) but is not linear and can be a bear to get right.
     
  4. KoolKat-57
    Joined: Feb 22, 2010
    Posts: 3,038

    KoolKat-57
    Member
    from Dublin, OH

    Ditto on that!
    I broke one on an old compressor that I had, and yes a new one is EXPENSIVE!:mad::eek:
     

  5. b-body-bob
    Joined: Apr 23, 2011
    Posts: 515

    b-body-bob
    Member

    Thanks to all for the info so far.

    I think someone's monkeyed with it before because it's labeled 120 on 150 off and now it's more like 90 on 130 off and for the last 10-15 psi it seems like it's working its guts out. Poor old thing's getting tired I guess.

    On the non-linear range side, I knew there was something like that, where you mess with it and the compressor never works right again. That's why for once I asked before I started experimenting.

    FWIW regulating it down doesn't help with pressure in, only pressure out.
     
  6. gimpyshotrods
    Joined: May 20, 2009
    Posts: 19,126

    gimpyshotrods
    ALLIANCE MEMBER

    Wow, nice relic. I would not use that compressor at all. At that age, you are begging for a tank explosion.
     
  7. MEDDLER1
    Joined: Jun 1, 2006
    Posts: 1,590

    MEDDLER1
    Member

    Like stated the main stud you see can be backed out to lower your pressure,but if the unit is acting up and changing pressure ranges on its own its time for another switch regardless. Is that whats goin on? Or do you just want the lower pressure? Honestly with a tank built in 1957 I would take it out of service myself. Trust me on that I do it for a living(air compressors) and have seen some scary shit happen with old tanks. You would be lucky if you only lose the wall its next too. NO JOKE.
     
  8. b-body-bob
    Joined: Apr 23, 2011
    Posts: 515

    b-body-bob
    Member

    No it's not changing on its own, I just want to lower the pressure.
     
  9. b-body-bob
    Joined: Apr 23, 2011
    Posts: 515

    b-body-bob
    Member

    FWIW about the tank being dangerous - the tank hasn't been over 50 PSI for years since I usually just keep enough pressure in it to inflate bicycle tires. The other day I was grinding welds and in the back of a drawer found an old cut off tool that works great for that because I can control the speed. But those things eat a lot of air, so I was leaving the power on and letting the compressor cycle, and that's what got me to thinking about dropping the high side pressure.

    I dunno what I'd do with it if I replaced it ... no room for something that big to just sit around. That doesn't even get into the question of where I'd get the money for a new one .. but I certainly understand what you're saying about an explosion being a catastrophe and appreciate the concern.
     
  10. gimpyshotrods
    Joined: May 20, 2009
    Posts: 19,126

    gimpyshotrods
    ALLIANCE MEMBER

    It is not an issue of it having been under pressure, any pressure, for that period of time. Compressing air causes the moisture in the air to coalesce. This collects in the bottom of the tank, causing it to rust.

    Nearly 55 years of this, and this tank is BEYOND DANGEROUS. There is enough stored potential kinetic energy in this tank, when pressurized, to kill, or at least maim you. Please take this to your local scrapper. The medical bills will cost more than a new compressor.
     
  11. 49ratfink
    Joined: Feb 8, 2004
    Posts: 18,129

    49ratfink
    Member
    from California

    wonder if there is some sort of way to get a tank tested to see if it is safe for use?? I'd look in the phone book for a compressor place and talk to them.
     
  12. 49ratfink
    Joined: Feb 8, 2004
    Posts: 18,129

    49ratfink
    Member
    from California

  13. Halfdozen
    Joined: Mar 8, 2008
    Posts: 624

    Halfdozen
    ALLIANCE MEMBER

    See if you can buy a new pressure tank and bypass the old one. Even if you end up buying a new compressor down the road, the extra tank gives you extra capacity for running air tools.
     

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