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Thread: Replacing compressor Drain

  1. #16
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    Quote Originally Posted by ChrisA Edwards View Post
    Wise words indeed, but realistically, and this is a question, how do you stop this rusting process?...
    Buy a stainless steel tank? I've never seen a compressor with one, though.

    JKJ

  2. #17
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    Quote Originally Posted by ChrisA Edwards View Post
    Wise words indeed, but realistically, and this is a question, how do you stop this rusting process? Moisture will get in as soon as the compressor runs.

    I am going to replace the drain valve with an easier to get to method, as described earlier in this thread.

    You don't unless you want to spend some big$$$$ for a lined tank, or a stainless steel tank. You prolong the life of the tank by periodically draining off the accumulated moisture.
    The air receiver's job is twofold; Capacity volume for the system, and the first stage of mechanical moisture separation. If your system is sized properly the air receiver will remove the bulk of the moisture from the system. Secondary air receiver tanks, coalescing filter traps, desiccant cartridge filters, coolers and dryers, do the rest.
    Your tank s supposed to condense the moisture in the air.
    "The first thing you need to know, will likely be the last thing you learn." (Unknown)

  3. #18
    I read this and the related previous threads. For the life of me, I can't understand why anyone wouldn't exhaust the condensate when you're finished with the compressor, or at the end of the day. Routinely draining it at least once a month is certainly inviting disaster...

    Ed

  4. #19
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    I recently repaired a leaking fuel tank on one of the tractors. One of the products I used was a thin epoxy for coating the whole interior of the tank. The first step is to take the inside of the tank down to bare metal with Muriatic acid. If I ever buy a new compressor, I'll strongly consider doing this to the inside of the tank. The new, lined surface is slick, hard, and I doubt it will ever rust again.

    After rinsing the acid out with water, I heated it over an outside cooker burner, on very low heat, until it was completely dry before pouring in the lining.

    Here's the product. It goes a lot farther than it seems like it would. I bought extra cans, but one was easily enough for the 20 gallon tank.
    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
    Last edited by Tom M King; 12-11-2018 at 7:43 PM.

  5. #20
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    I think a coating of motor oil spread all over the tank might stop rust? It will not be carried into the airstream to harm finishes. Of course water sinks below oil so it may no really help at the bottom.
    I do have two surplus stainless oxygen tanks but that supply is gone after 80 years. I understand new planes use liquid oxygen so no pressure tanks are flown anymore.
    Bil lD.

  6. #21
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    Quote Originally Posted by Ed Edwards View Post
    I read this and the related previous threads. For the life of me, I can't understand why anyone wouldn't exhaust the condensate when you're finished with the compressor, or at the end of the day. Routinely draining it at least once a month is certainly inviting disaster...

    Ed
    Ed
    You won't get it out that way either, unless you have a fairly large orifice in the bottom of the tank.


    Given time, and it doesn't take that long, a static receiver tank can be rid of the accumulated moisture. Once this is done there is no reason to exhaust the entire receiver tank, and there is a very good reason to leave that receiver tank full of air when not in use.
    Once the receiver tank has performed it's function, mechanically separating moisture from the compressed gas, the moisture content inside the tank is now reflective of the ambient air temperature and the pressure inside the receiver tank. If both stay static, then no more moisture is coming out of the compressed gas, but temperature is going to be a dynamic variable and as it lowers, during the night, more moisture will condense. Being that the receiver tank is an enclosed volume, as the temps increase during the day, no more moisture can accumulate. If you have an auto drain you will remove all available moisture from that tank in a few days. Once a month is a little bit long of an interval, especially if the compressor is being used during the interval.
    You want the air in the receiver tank to be as low in moisture content as possible. If you were to exhaust the entire tank after each use, and then fill the tank just prior to use, all of the air inside of that tank is in a saturated moisture condition. This air has moisture now, in the form of vapor, which is going to move through the system very quickly. Even the best desiccant filters cannot keep up, and you will have moisture coming out at the end of the line, and into tools and spray guns. Sometimes enough that you can actually see it.
    Once the entire system is saturated no amount of filtering, or refrigerating, is going to remove this moisture until the system is at stasis, and then they can begin to remove the moisture.
    In the case of the OP's compressor, that is is a very small pancake type compressor with a 6 gallon receiver tank. It could be left pressurized in between uses and the moisture removes, by tipping it on it's side, putting the drain valve at the bottom, and blowing it down. But generally they're just turned on prior to use and the tank comes up to pressure. Since their intended usage is pneumatic nailers, the moisture isn't a big deal. I have/had this same compressor for many years. My small portable is a Rolair JC10 now. The old 6 gallon tank is a secondary air receiver tank in my system.
    If you have a large stationary air compressor, the receiver tank should be kept pressurized at all times to allow it to perform it's primary function of moisture removal.
    Last edited by Mike Cutler; 12-12-2018 at 4:43 AM.
    "The first thing you need to know, will likely be the last thing you learn." (Unknown)

  7. #22
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    Quote Originally Posted by Mike Cutler View Post
    If you have a large stationary air compressor, the receiver tank should be kept pressurized at all times to allow it to perform it's primary function of moisture removal.
    You have way more knowledge of this whole process than myself, so as my compressor was kept pressurized for about 3+years before I decided to drain it, is that why I saw such a little amount of water come out when I finally did drain it?

  8. #23
    I think the reason we don't see stainless steel tanks is that stainless does not take stress well at all. The continuous expansion of the tank would make fatigue cracks in the metal.

  9. #24
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    Quote Originally Posted by ChrisA Edwards View Post
    You have way more knowledge of this whole process than myself, so as my compressor was kept pressurized for about 3+years before I decided to drain it, is that why I saw such a little amount of water come out when I finally did drain it?
    Chris
    It could be.
    I would have expected more moisture than that to accumulate after three years, but ????.
    The color of that fluid would bother me though.

    I've been maintaining large industrial air systems for most of my working life, in a nuclear power plant. Primarily the process control part of the systems, but I've done a few overhauls also. The hard part for me is scaling it down to a small workshop, or garage shop. All of the system parts work the same though, it's just the size of some of them that is different.
    "The first thing you need to know, will likely be the last thing you learn." (Unknown)

  10. #25
    Mike
    Thanks for the enlightenment. You contributed a wealth of info that I was totality unaware of.

    Thanks, Ed

  11. #26
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    Quote Originally Posted by Ed Edwards View Post
    I read this and the related previous threads. For the life of me, I can't understand why anyone wouldn't exhaust the condensate when you're finished with the compressor, or at the end of the day. Routinely draining it at least once a month is certainly inviting disaster...

    Ed
    To me that's one of the advantages of extending the drain with pipe. Assuming the drain is at the lowest part of the tank, any water should sit in the pipe, not in the bottom of the tank. I don't use a compressor much, if it runs 15 minutes a month it's been a busy month but have never gotten more than a few drops of water out of it.

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