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Technical 2-Stage Compressor Pump replacement recommendations??

Discussion in 'The Hokey Ass Message Board' started by ziffer, Nov 11, 2020.

  1. ziffer
    Joined: May 4, 2005
    Posts: 146

    ziffer
    Member
    from michigan

    Gotta replace the pump on my compressor. It is aluminum construction and it is shot. Looking for recommendations for a 2 stage maybe cast iron if it will last longer. Currently on a 80 gallon tank running 230v 6 HP motor.

    Thanks
     
  2. 1ton
    Joined: Dec 3, 2010
    Posts: 429

    1ton
    Member

    Eaton pumps are all cast iron with forged con rods. Their tech line is very helpful and they can give you proper pulley diameters per the rpms of your motor so the pump runs at the proper rpm. I bought a 10 hp. 43 cfm 175 psi pump from them. Its low r's so it's quiet. I dropped the pressure switch down to 125 psi. and am using a 5 hp 240v. single ph, motor and it works great. eatoncompressor.com
     
    Last edited: Nov 11, 2020
  3. treb11
    Joined: Jan 21, 2006
    Posts: 3,613

    treb11
    ALLIANCE MEMBER


  4. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,873

    2OLD2FAST
    Member
    from illinois

    Quincy pumps used to be top of the line ....
     
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  5. Flathead Dave
    Joined: Mar 21, 2014
    Posts: 3,074

    Flathead Dave
    ALLIANCE MEMBER
    from So. Cal.

    Can you rebuild it?
    Is a rebuild kit available?
    Sent from my SM-G973U using The H.A.M.B. mobile app
     
  6. Quincy 4 x 3. Cast iron construction, parts readily available, and they last. 6 HP is on the edge of running it, but a smaller motor pulley would work.
     
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  7. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,760

    dirty old man
    ALLIANCE MEMBER

    Before you buy a compressor pump requiring 6 hp to pull it be sure about that 6 hp.
    An aluminum compressor sounds like what I like to call a "Home Depot" type of compressor, and most of them use some sort of Chinese formula to rate motor hp. Compare the amperage draw of the motor to that of a brand name US built motor, and if the figures aren't very similar you'll know you have one with optimistic hp rating. Then it's "back to the drawing board":eek:
     
  8. Budget36
    Joined: Nov 29, 2014
    Posts: 4,888

    Budget36
    Member

    I’d wonder about the 6HP as well, if a 1750rpm motor, you’re good, if 3450 etc, that limits your pump choices

    not sure how they get the extra rpms on the motors, as normal the # of poles is standard for rpms, but somehow they get them to spin a bit faster and it raises HP rating. I/e my small craftsmen is rated at 5.5 HP but spins 3600 rpm. I bought it in the 90’s. My buddy with a similar Craftsmen but older is 6 HP at 3450


    Maybe @Crazy Steve can explain the extra RPMs?
     
  9. 1934coupe
    Joined: Feb 22, 2007
    Posts: 4,198

    1934coupe
    Member

    Quincy 325 pump. Pressurized oil system and in the top of 5 HP compressors.

    Pat
     
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  10. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 5,272

    Ebbsspeed
    ALLIANCE MEMBER

    1750 and 3450 are the loaded RPM vs 1800 and 3600 being the unloaded RPM.
     
  11. Budget36
    Joined: Nov 29, 2014
    Posts: 4,888

    Budget36
    Member

    I don’t think so, 1750 is unloaded ( your mention) and generally will be 1725. So look at “normal” motors and rpms, look at poles in the motors. That’s what (as I know it) determines rpms. Not talking about synchronous v non-syncronous motors and slip, just in general about how you take a motor that last week say ran at 3500 rpm, and now this week we can make it run at 3600 rpm?
     
  12. 1934coupe
    Joined: Feb 22, 2007
    Posts: 4,198

    1934coupe
    Member

    A change in pulley diameters will change the RPM, and the faster they run the more noise and heat they make. Keep all these factors in mind when choosing my friend.

    Pat
     
  13. 1ton
    Joined: Dec 3, 2010
    Posts: 429

    1ton
    Member

    Seems nowadays that alot of new compressors go to 175 psi. Even the little pancake ones for contractors/remodelers. Is this really necessary? Listen to these compressors running. They easily will bring 125 psi. and run cool. It's when they are creating that extra 50 psi. is when they start to work hard and create more heat which, in turn, will create more water. Proved it to a buddy of mine. He was bitching about his older, well used compressor. That thing got smoking hot trying to get that last bit of pressure. We changed the switch from 175 to 125psi. It ran cooler and the water issue diminished greatly.
     
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  14. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,760

    dirty old man
    ALLIANCE MEMBER

    ^^^^^^^^^^^ I run my old 60+ yr. old Gardner-Denver that was intended for a 5 hp motor on a 7.5 hp, slightly overdriven to take advantage of today's much improved synthetic oil's lubricating abilities. But I also limit it to 125 psi. Still have plenty of air though because the compressor pump and motor are mounted on a 60 gal. tank which sits atop an 80 gal. tank:)
     
  15. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 2,873

    2OLD2FAST
    Member
    from illinois

    It takes compressor X , X amount of time to produce X volume of air at X pressure ,whether the storage vessel is 10 cu. ft or 300 cu. ft .
     
  16. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,760

    dirty old man
    ALLIANCE MEMBER

    ^^^^^^^^^^^^Agree with this, but with 300 cu. ft. of storage, it will take a helluva lot more air usage before that old antique, half worn out compressor has to start up and try like hell to keep up with that bead blaster than it will with 10 cu. ft. of storage. Might even get the task at hand completed before I have to stop and wait on the compressor to catch up:):cool:
     

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