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Thread: air dryer

  1. #1

    Post air dryer

    im getting a fair bit of water in my airlines,i have a decent water seperater but it doesnt get it all. what i want to do is build a refridgerated dryer.a idea of mine was to get a section of pipe and fill it with stainless steel scrubbing pads , mount it in my beer fridge and plumb my air thru it with a auto drain on the outside of the fridge. anybody tried making one ? or has a better idea?

  2. #2
    Join Date
    Apr 2003
    Posts
    316

    Post

    This may be an offensive question but:Have you drained the tank recently?I live in the land of humid air and have almost no problem with moisture in my lines.I'm not painting so I may not notice if there is any.A good trap will catch 99% of the moisture unless it is being overwhelmed by water in the tank.It could be the trap isn't large enough for the volume of air going through it too.I run a glass bead cabinet and several air drills and die grinders and don't recall any moisture coming out under normal use unless I forget to drain the trap.
    Robert

  3. #3
    Join Date
    Apr 2001
    Location
    Maine
    Posts
    6,730

    Post

    I've got the same problem. (And yes, gamachinist, I drain the tank frequently!) Your idea sounds plausible to me, but I know very little about air dryers. I assume you know that the water separator ought to be put at the point of use, not at the tank.

    ----------
    Try to make a living, not a killing. -- Utah Phillips
    Don't believe everything you know. -- Bumper sticker
    Everybody is ignorant, only on different subjects. -- Will Rogers
    There are lots of people who mistake their imagination for their memory. - Josh Billings
    Law of Logical Argument - Anything is possible if you don't know what you are talking about.

  4. #4
    Join Date
    Nov 2002
    Posts
    296

    Post

    I use an aftercooler with my 20HP system. It utilizes a 1/4HP driven fan which pulls air across the coils. I get virtually no moisture in the shop air lines.
    There is an automatic drain on the compressor that is adjustable for frequency and duration of blowdown. The aftercooler uses a float type separator/drain.
    You can tell how humid a day it is by the amount of water released.
    Before getting the aftercooler, we had to drain the traps at the machines every day. Now, they stay dry.

    Les

  5. #5
    Join Date
    Apr 2003
    Posts
    316

    Talking

    My trap is on the wall beside the compressor.I've got 5 or more points of use so I couldn't afford that many traps.I have my outlets off the side of the line and a drain below.I drain the lines about once a year and get very little moisture from them.(A short spray at most).The main trap gets drained as needed and the compressor when I notice it short cycling because of loss of tank space.Maybe the humidity is higher where you are it's just not as hot!
    As for draining the tank,I worked in a shop that had an automatic drain on the line but not the tank.They hadn't drained the tank and it had filled with water to the bottom of the air outlet.You could work for about 60 seconds or so and the trap at the glass bead cabinet was full.The forman didn't belive me until he started cutting with a die grinder and got soaked by the exhaust.Looked outside at the compressor and the auto drain was running a steady stream of water.That's when they remembered they hadn't drained the tank in so long no one could remember.
    Robert.

  6. #6
    Join Date
    Dec 2002
    Posts
    5,725

    Post

    LORD, don't put a piece of 3 inch pvc pipe up and use it for a water trap, My lil brother and the other worry warts will lynch me.

    It acts like a bomb they tell me.. MY new HVLP spray rig blows a lot of air, with the large tip for metal flake it could hardly keep up.. I was blowing water with the paint, I have a verticle compressor too.

    [This message has been edited by ibewgypsie (edited 06-23-2003).]

  7. #7
    Join Date
    Feb 2003
    Posts
    1,319

    Post

    I've got the same problem with water and have the same reply to WS. I also have a large (2 1/2") trap. On a whim I filled the bowl with desicant for drying flowers. Worked great until the oil in the oiler driped bacward into it while it was pulled of the wall to make a new bracket. The desicant can be dried in the microwave and reused. It would last even longer in a secondary seperator. The problem I saw was that water was clinging to the trap and getting caught in the air flow.

    I have no idea if this was a "smart" thing to do or not, as I said I tried it on a whim and it worked for me.

    -Dave

  8. #8
    Join Date
    Jan 2003
    Location
    Deep in the Heart of Texas!
    Posts
    5,721

    Post

    On the compressor I use for painting, I use a "homemade" after cooler. It's actually an old outside unit from a house air conditioner. The compressor was shot but the fan (220v) still worked great. I pulled the compressor out of the unit and wired the fan to a separate switch. I brazed new fittings to the ends of the coil and piped the air from the tank through the coil. From the coil, it goes to a filter/separator.
    The coil/unit is mounted higher than the tank so moisture runs back to the tank. As soon as I get a "RoundTuit", I plan to add an automatic tank drain. In any case, I don't have any problems with moisture in the lines. When it's over 65* dew point, I don't paint anyway.
    Make sure you get one that has at least 1/4" tubing (most are). The coils are made to carry at least 350psi. so it'll take anything you throw at it.
    Also, Mine was free but I've seen units in the salvage yard. This is the time of year that many people replace the compressor unit (outside unit) so it shouldn't be hard to find one. Make sure the fan works!

  9. #9

    Post

    i just drained the tank the other day it didnt seem to make much difference, i have drain cocks all over the place and i crack them every day,i get water out of almost all of them, im thinking of going to a desicant dryer in the booth but i think it will be overwhelmed.

  10. #10

    Post

    To get the water out of the air you must get the temp down in the line leaving the tank. One easy way is to run the air throught a few hundred feet of copper pipe.The metal will wick the temp down to a point that the air can't hold as much water. The longer the pipe the cooler it gets. This is why water sep. installed close to the tank don't do as much good as one farther away because the air is hotter closer to the tank. Now running a few hundred feet of copper is easy. Get 10 ten foot lenghts of 1/2" copper pipe and some tee's and ell's and connect them with tee's spacing each pipe about a inch apart side by side.

    ________________________________
    In> (________________________________)
    (________________________________)
    (________________________________)
    (________________________________)
    (________________________________)>Out
    T T
    drain drain

    The reason for so many lenghts of pipe is the air need to branch out and going slower throught the manifold in order for the heat to conduct to the pipe better and it allso will keep the air flow from dropping at the exit pipe. If you need more cooling, put a small fan blowing on the pipes.

    Dan

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