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Air Compressor Upkeep

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  • Air Compressor Upkeep

    So all this talk about exploding sand blasters and shop air compressors has me thinking about my 12 year old home depot el cheapo air compressor.

    Single stage with something like a 50 gallon vertical tank.

    No rust on exterior or any signs of wear but I have NEVER done anything to it other than check compressor oil and open the bottom vent once in a great while to blow condensation out of the bottom of the tank.

    The condensation comes out rusty colored but no chunks or flakes that I've ever noticed.

    Is there a recommended maintenance procedure or test period for a home shop air compressor? What is the typical life span of one of these things? Heck I can think of half a dozen friends/neighbors with compressors as old as mine or even much older that I'm sure have never been maintained.


  • #2
    Inside the tank, it doesnt take long for air turns to water. Before you use the compressor, let some air out of the bottom and that will let out water. Im not sure where rust is coming from unless it sits a long period of time.


    • #3
      Without a location, its hard to be specific with advice. If you are in one of the dry areas of the country a simple drain down prior to each use would most likely fill any needs you may see. It would be better if you waited and hour or so after the last usage and then drain just to give the air in the tank time to cool and release latent moisture as well as not leaving whatever moisture is in the tank to sit on the bottom of the tank and promote rust.

      If, on the other hand, you live in an area with higher humidity it wouldn't be a bad idea to install some form of automatic tank drain. I've been satisfied with an electrically timed 'spitter' wired to kick into it's cyclings whenever the air compressor is pumping, but I've also heard the cheap Harbor Freight auto drain works well after a bit of the usual Harbor Freight re-engineering.
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      • #4
        Testing Procedures

        If you are concerned with the safety of your air tank, you can have it Hydro-Static tested. This is where all pressure relief valves and hoses are removed, the tank is filled with water, then a hand pump is used to increase the pressure to 1.5 times maximum allowable working pressure(MAWP). With the small volume of air used in this test, if the tank ruptures it does not become a rocket or a bomb. Most near any company that services comercial air compressors can do this test for you(for a fee). Just look them up in the phone book.
        Where I work we are required to have our tanks with pressures over 100 psi tested this way annualy, tanks with less than 100 psi every 3 years. Usually though the ones under 100 get tested annually too since the guys that do the tests are already onsite(if they are not hard pressed for time, which they generaly are not). We have the personnel already on staff certified to do this, with their own equipment.
        Just look up a reputable air compressor service company in your area and ask about getting this done.
        Senior Member
        Last edited by Bistineau; 01-11-2012, 01:52 PM.


        • #5
          I live in Connecticut. I certainly don't use the bleader every time I use the compressor. Maybe once every 3-4 months, of course I only use it for a few hours each weekend.


          • #6
            If you have had this compressor for 12 years and only CHECKED the oil you should consider changing it sometime. If you pull a sample out in a piece of clear hose it will probably look green like split pea soup or worse. Most compressor oil is about honey colored when new. When it starts absorbing moisture from the air it changes color and loses some lubricating ability.
            Remember the inside of your tank is uncoated(no paint/primer, bare metal). Brown condensate coming out is a sign of rust internally, rust never sleeps.


            • #7
              Don't hit the panic button, change the oil with some new comp oil, let a little water out on occasion, its easy to forget, got a couple gallons out of mine a while back and its due for its 5 yr oil change, its a daily driver though. Haven't taken any great care of the thing, got thousands of hours on it. Almost 40 yrs old, been on 24/7


              • #8
                Your tank is not going to blow up if that is your concern.
                What will happen when the tank rusts through, is you get a pin hole first.
                The escaping air will alert you that the tank is a goner.

                I recently used a small Craftsman air compressor that had not been run in a couple of years.
                I bought this brand new 35 years ago.
                After is started it never shut off.
                I looked at the gage and it read zero.
                The small pinhole was letting rusty water dribble out the bottom of the tank onto the shop floor.

                End of life for that little compressor tank, but no explosion.
                There is always a very small weaker spot on a rusted tank, and this is what gives out first.

                You have tanks explode when the max pressure has been exceeded by quite a bit and the tank is rusted. Exceeding the max pressure will not happen provided you have a working regulator.

                My large compressor is a Quincy 325 two stage.
                Some years back I decided to spend $116 and install an automatic blowdown on the tank.
                This is adjustable and I have mine set for a 5 second burst of air vent every 45 minutes.
                This blow down stays on 24/7, as does the Quincy.

                I used to turn the Quincy on only when I wanted air and I had a problem with the valves on the high pressure side rusting up badly.
                I had to remove and clean them every 6 months.

                The guys at Quincy told me to run the compressor more often because not doing so was creating the rust problem.

                I took their advice and installed the blowdown and it has been 3 years since I have opened up the valves to clean them.
                Running often is good.
                Changing the oil every 3 months is also good.
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