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Thread: Old Compressor

  1. #26
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    Re: Old Compressor

    If you cannot find direct replacements Niagara Piston Ring in Corry, PA could custom make them for you. It's where I go for all my antique engines - they cut them to whatever dimensions I need. And, it's not as expensive as it may sound! Seems like it was about $65 for a set of 3 that were for about a 5" bore, and were 1/2" wide.

  2. #27
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    Re: Old Compressor

    salem747, why are the pistons 2 different diameters?
    dave.

  3. #28
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    Re: Old Compressor

    The pistons are two different sizes because the pump is a two-stage pump. The big piston pumps the air partially up to pressure and then that compressed air goes into the second smaller cylinder where the smaller piston then compresses it some more. Sometimes there is a loop or piece of finned pipe connecting the air coming out of the big cylinder into the intake of the smaller cylinder in order to try and cool the air off a bit.
    The best laid schemes ... Gang oft agley ...

  4. #29
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    Re: Old Compressor

    rvpc MoonRise covered it pretty well. You can always tell a 2 stage compressor from the different sized pistons, and the fact that stage one feeds into stage 2 an then into the tank. A single stage, 2 piston compressor usually has 2 separate intakes, one for each cyl. and usually the out put goes into a T that then enters the tank.

    2 stage compressors usually make 175psi or more, but have lower CFM's than the same HP 2 cyl single stage compressors. The single stage units making 125 psi max or so. This difference makes a big difference in price frequently on new units.
    .



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  5. #30
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    Re: Old Compressor

    thank you.
    dave.

  6. #31
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    Re: Old Compressor

    Yeah I am thinking for a ring I might have to get one fabbed. It's almost a shame that it is the oil ring because the other rings are just plain and would be cheaper to make. This one has a groove around the outside with small holes drilled through it. The big oil ring has a groove but more like slots cut into it.

    But I guess if any ring is going to break it will be the oil ring because it is quite a bit weaker than the compression rings.

    I have been out of town all week so I haven't done much research on it yet.

  7. #32
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    Re: Old Compressor

    Update: Since the tank was no good I looked into a new one. Found out that the pump is a Brunner A-212. There is a company in Toronto that still makes rings etc for them apparently these are bought and last for a lifetime!

    I found another complete 3-phase Brunner horizontal in Ottawa about 3 hrs drive from home for $375. It is a little newer, 1962 or 1964. It was used in a agricultural college wood shop for cleaning off the tools, the wood shop has been shutdown for 10 years and the guy who had it is a HD mechanic who teaches there and got this machine in return for some extra work.

    It has the original metallic blue paint and all of the original decals (what ever happened to decals anyway?) I put on my 1958 3hp motor and a couple of new belts and it runs like a champ, very quiet! The only problem I had besides getting all of my fittings clocked properly with no leaks was that they had broken the original plumbing from the head to the tank and replaced it with soldered copper pipe. So when I soldered the pipe back on (wouldn't fit under the canopy on my truck without disassembling) I kept getting little chunks of solder in the check valve so when the motor stopped the unloader valve would open and let all the air out.

    I am no plumber so I was obviously using too much solder. Just put it back together and heated the joints, no additional solder. Seems to be holding air now.

    I still want to finish the A-212 pump. It is a 2 stage pump for 175psi and I can probably get some good coin for it or just keep it!

    Pics to follow.

  8. #33
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    Re: Old Compressor

    In case anyone else has an old Brunner and you are looking for parts:

    http://www.atmosphair.net/ they are near Toronto and do have gasket sets, rings etc.
    Attached Images Attached Images    

  9. #34
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    Re: Old Compressor

    great thread . sorry, i PM'd you before i saw this thread.

    what size did u say tha tank was?
    thermal arc 252i - millermatic 350P - miller XMT, cp300ts, 30a 22a feeders, buttload of other millers, handfull of lincolns, couple of esabs - Hypertherm 1250 G3

  10. #35
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    Re: Old Compressor

    60 Gallon tank. This pump is a 2 cylinder single stage unit. I don't really need 175PSI but I am going to try and get the other pump running.

    I would like to figure out how many CFM it is capable of. I could probably calculate it. The intake will suck your hand right tight!

    This has been a really fun project. Some detective work, some history lessons, a little mechanical stuff and I saved myself a couple of grand in the process!!! Not bad.

  11. #36
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    Re: Old Compressor

    i think the formula is : CFM displacement@ 0 = Bore x stroke x actual pump RPM (but would be a drop @90psi) gotta find the formula for that.

    pump speed is calculated : pump speed = diameter of the pulley on the motor X the speed of the motor (via;1750 or 3450) /divided by the diameter of the pulley on the pump.

    -that's not the same pump on page 1 ?
    thermal arc 252i - millermatic 350P - miller XMT, cp300ts, 30a 22a feeders, buttload of other millers, handfull of lincolns, couple of esabs - Hypertherm 1250 G3

  12. #37
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    Re: Old Compressor

    Nope, still need the oil ring for the 2 stage pump. I can't find the bore & stroke of the newer pump without taking it apart and have yet to find any manuals for these old pumps.

  13. #38
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    Re: Old Compressor

    pv = pv , pressure in psia (absolute). 0psig (gauge) (atmospheric) is 14.5psia 90 psig is 104.5 psia

    my old pump = 3" bore, 3.5 stroke, single cylinder and is supposed to run at 550rpm

    24.7 cu in displacement x 550 rpm =13585 "3 = 7.8 cfm @ 14.4psia

    14.5 psig* 7.8 cfm = 104.5 psig * 1.08 cfm

    should put out 1.08 cfm @ 90 psig

    Hmmm how many HP should I drive this with???
    Last edited by fredf; 02-11-2010 at 10:41 PM.
    -- fred

    Lincoln 180C MIG

  14. #39
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    Re: Old Compressor

    somethings wrong...............noway it should drop from nearly 8 CFM to 1cfm..

    my brains tired right now. I think i remember the rule's like 1HP or 4.3 amps per/ 3 cfm

    i think thats 220V - the amps required on a 110 motor would nearly double to like 7.5amps per HP , yes

    i may correct this later , dont hold me tooit.
    thermal arc 252i - millermatic 350P - miller XMT, cp300ts, 30a 22a feeders, buttload of other millers, handfull of lincolns, couple of esabs - Hypertherm 1250 G3

  15. #40
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    Re: Old Compressor

    Just got the new set of rings for the Brunner 212 pump. $74 CDN for a complete set (both Pistons) of brand new rings. I asked for pricing on the gasket set, $72 so I told them I didn't want them but they sent them anyway! Woulda been fine if they didn't charge me for them, but they did so I sent them back.

  16. #41
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    Re: Old Compressor

    After you get the motor and pump all fixed up be sure and inspect and /or test the tank. Sitting around for a while may have allowed internal moisture to rust the inside of the tank to the point where it won't stand up to the original pressure rating. Even if there is no evidence of moisture the damage could have already been done . Given the age of the tank this could potentially be dangerous. Typically tanks do not explode but develop pin holes that gradually grow to the point where the tank won't hold enough pressure to operate anything. However, older tanks were sometimes more brittle.

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