Air comp ? OT sort of

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I seem to be having a problem with my air compressor, it appears to be injecting water into my paint. I already have an air water filter but the water still is present. What else can I do to keep the water out. It is sure making a mess of my finishing.
Rich
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There should be a drain on the compressor. You need to open it regularly, to drain water out of the compressor. Dan On Wed, 18 Aug 2004 22:15:35 GMT, "Searcher"

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The big problem with the design of small air compressors systems is that they don't have a way to properly cool the compressed air that is exhausting from the compressor so that the moisture will condense out of it. If it was allowed to cool before you tried to use it the moisture would condense out and the air would be dry. The water could then be separated and you would have the dry air that you want. Unfortunately the air compressor manufacturers have never addressed this problem in their designs. They must all live in Arizona or some other desert climate. This is a problem for the rest of us who must live and spray paint in the more humid parts of the world.
As a compressor runs and raises the pressure of the air, it also increases the temperature of it. The moisture that is in this air will only remain a vapor if the air remains at this high temperature. As it cools in the tank and your air lines this moisture condenses out of it and becomes a problem. Also, since warm air rises above cooler air, this warm humid air stratifies and floats above the cooler air in the tank. In most cases the compressor design puts the air outlet from the tank right next to the air inlet from the compressor so any air that you draw out of the tank is still hot (and full of moisture) when it leaves the tank, but cools as it flows through your lines. As it cools the water condenses out of it causing the problem that you are experiencing. It would be more desirable if the air outlet from the tank could be located toward (but not at) the bottom of the tank. This would give the hot air that is entering the tank time to give up it's heat through the tank walls and the moisture time to condense out of it and fall to the bottom of the tank before it reached the outlet point and your air lines.
If the design of your air compressor had included a means of cooling the compressed air before it reached the tank, then all of the moisture vapor would be condensed out of it and would fall to the bottom of the tank where it could accumulate to be drained at your convenience. Then all of the air in the tank would be cool and would have given up it's moisture long before it left the tank and entered your air lines no matter where the tank exit was located.
I modified my air compressor several years ago to correct this and have had no water problems since. I had to do this because I now live in North Carolina where the humidity is frequently so high that we get thunder showers almost every day in the summer months. I couldn't use my air compressor to do much of anything but use it as a great water pistol. I can now do sand blasting and painting and I never have any water problems any more.
Here is the fix:
I connected an old air conditioning condenser coil that I got out of an old import car (don't remember the make or model) in the hot air line that ran between the compressor outlet and the tank. The trick is to find a coil that is about the right size with flare fitting connections and an adequate tubing size to handle the air flow out of your compressor (mine was 3/8). Since the running pressure of this part of automotive air conditioners is typically in the 3-400 pound range these coils are more than strong enough to handle the working pressures of home air compressors, so safety shouldn't be a concern. I mounted this coil so that the fan in the compressor pulley pulls air through it, cooling down the hot air that is coming out of the compressor before it reaches the tank. You should connect the compressor outlet to the top connection of the coil and the tank inlet to the bottom connection. Once the air has been cooled, the moisture condenses out of it and it falls to the bottom of the air tank. The entire tank will now stay at ambient temperature and it won't matter where the outlet connection is located, so long as it is above where the condensate collects. You will still need to drain the tank frequently, in fact, a little more frequently than you used to. The dry air in the tank will never again have enough moisture in it to condense in your air lines.
I still use one of those "orange ball" filters at my spray gun, but I do it more as a safeguard for dirt and debris since it never sees water any more.
--
Charley

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Searcher wrote:

When's the last time you drained the tank?
-- Jack Novak Buffalo, NY - USA (Remove "SPAM" from email address to reply)
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it's condensing out in your hose or at the nozzle. you need to have 2 water traps, one at the compressor, one near the end of the hose. if it's really humid out, you might need an air dryer too.
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I drain the tank several times a day. The main water/partical filter is at the tank and the hose is only 25 ft long. I guess then I would need an air dryer? rich

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well, maybe. if you use copper piping instead of a long rubber hose, have the piping have a downward slope to the air tap, and a water trap at the tap, you might be able to avoid having one.
hf has an air dryer that isn't an arm and a leg.
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber@211

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If anyone in Eastern MA wants a real refrigerated air dry, cheap, I have a couple. Want to sell at least one.
GTO(John)
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whats cheap? As you can see I am having finishing problems and you seem to be right on the mark!
rich

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On Wed, 18 Aug 2004 23:09:01 GMT, "Searcher"

the water separator needs cool air to work. the air right out of the compressor is hot enough to keep the moisture in it right through the separator. try a length of hose between the compressor and the separator.
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Great thought, I will change my set up around to give the air a chance to cool down. I am not getting much water in the separator come to think of it.
Thanks for the tip I'll let you know how it turns out.
Rich

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Also - get one of those orange bulbs that go on your gun. They are water traps and they screw into a standard 1/4"NPT fitting. One side is male and the other is female so you may need to buy an adapter as well, depending on what your gun needs. These things work very well. Very well. I use one on all of my spray guns and I've shot cars with a small compressor that thought part of it's purpose in life was to provide a refreshing mist as well as compressed air. I get absolutely no water through these things and have not experienced any finish problems since going to them years ago. And - as was said before, drain your tank - right before you are going to spray.
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Mike. What little orange bulbs? Thanks, JG
Mike Marlow wrote:

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Here's the url...
http://www.motorguard.com/air_3.html
Scroll down to Spray Gun Filters, model D-12-1.
These things are available in most auto parts stores and from any automotive paint supplier. Just screw it on your gun and forget about it. They last forever with occasional spraying.
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Orange bulb? Forgive me but I have no idea what an orange bulb is. That sounds like my answer! Where do I go to look for one?
Rich

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Try it - you'll love it. The url is http://www.motorguard.com/air_3.html . Scroll down to where it says Painting: Spray Gun Filters. The product id is D-12-1. You screw one on and forget all about it. They last for years with occasional spraying. With the amount a wooddorker would do you'll only ever need one.
They are available in most auto parts stores and in all automotive paint supply houses. I think they're around $5.00 or so, but I'm not sure. When I need to get one I don't really pay attention to the price - it's one of those things that if you need one, you need one.
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One of the things I've found to contribute to moisture in the air stream is too small a tank. I used to use a gallon tank on a portable used with a pneumatic drill. Water out the drill's exhaust all the time. Needed to be portable, water didn't hurt the drill. Hooking the same drill to a compressor with a 20 gallon tank give no condensate out the exhaust. How big a tank are you dealing with?
bob g.
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I have a 60 gal I/R comp
wrote:

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try moving your water filter away from the compressor. get a 10 or 25' legnth of hose to run from your compressor to the filter, then add another legnth to your paint gun. Make sure the tank is drained. I have painted several cars and this certainly helps!
Dave

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Today, I did move the water trap from the tank with about 6 ft of hose between the tank and the hose reel. I drained the tank and hopefully I will see a difference when I go to use the sand blaster this weekend. I am also going to look in my area for the "orange bulbs"/
Rich \

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