What kind of dryer should I be considering for my 30 gallon 5.9CFM @90 compressor. I'll be spraying some small panels with epoxy primer, slick sand, and urethane primer in my garage with an Eastwood Concours gun. No bc/cc. I live near the beach so I'll be dealing with high humidity levels. Thanks for your input.

zman4011 wrote:What kind of dryer should I be considering for my 30 gallon 5.9CFM @90 compressor. I'll be spraying some small panels with epoxy primer, slick sand, and urethane primer in my garage with an Eastwood Concours gun. No bc/cc. I live near the beach so I'll be dealing with high humidity levels. Thanks for your input.

Without building a piping system with drains, you could probably get away with those disposable inline filters that screw to the handle of your gun with a long enough hose to allow the air to cool and water to condense. I've never used them, so I don't know how often you should change them. Others here will chime in on that.

If you want a permanent setup, then you could run circuitous and sloped piping, or add an automotive a/c condenser and water trap tank between the compressor head and main tank.

I live in the panhandle of Florida not far from the sound and Gulf, and the humidity is sometimes miserable. I did this:

It's a little complicated, but I can run a DA sander all day long--without the desiccant filter--during high humidity days with nary a droplet of water coming out of the sander and only about 1/2 tsp of water accumulating in the main tank. The water trap tank catches a lot of water. The condenser cools the hot air coming out of the compressor head. It works well. I had to double them up due to CFM considerations.

Lol you do realize a condenser it self doesn't work with out a source of air blowing through it's fins and even if you did you would be making warm air/water come out

Littlevil wrote:Lol you do realize a condenser it self doesn't work with out a source of air blowing through it's fins and even if you did you would be making warm air/water come out

Actually, you're wrong, lol. I used a non-contact thermometer to measure the temperature of the input and output. Without the fan I get about a 100 degree temperature drop. With the fan, more like a 150 degree drop.

The whole point is to get warm liquid water coming out, i.e., you want to condense the water that is in the compressed air and remove it. That's what the water trap tank does. With or without the fan, I can see water trickling down the hose from the condenser to the water trap, where it stays.

I'm past the theory. I've proven the concept.

How did you prove it? Zero industrial grade air dryers use your theory, i wonder why? You must drain water and change filters a ridiculous amount. Let me know how long your compressor lasts with that setup

Littlevil wrote:How did you prove it? Zero industrial grade air dryers use your theory, i wonder why? You must drain water and change filters a ridiculous amount. Let me know how long your compressor lasts with that setup

Oh gee, I don't know. Maybe because I can run my DA sander all day long--with the QC-3 bypassed--on the most humid of days here in NW Florida with not a droplet of water coming out of the sander or any of the various drain valves I've installed past the main tank. Or maybe when I drained my main tank after two days of applying primer and paint to a truck I get at most a half teaspoon of water. Or maybe the evidence lies in the water separator just prior to the QC-3; not a drop of water after applying 3 coats of base and two coats of clear when the humidity was 78%. Or maybe it's the cup of water that comes out of the water trap tanks that leads me to believe that it is removing the moisture. Or maybe it's the stream of water I can see trickling down the clear hose that goes from the condenser to the water trap.

And your are wrong again. Refrigeration type dryers use the same principle: moisture-laden air goes through coils that are in contact with cold refrigerant. The water condenses out and is caught in a separator and drained away. In my case, the refrigerant is cool air blowing across an a/c condenser. Exact same principle.

Here's a link to Grainger: http://www.grainger.com/category/refrigerated-compressed-air-dryers/compressed-air-treatment/pneumatics/ecatalog/N-kk5

You can buy one for $1000 or apply some ingenuity and make one for $100.

As far as draining water and changing filters a "ridiculous amount," once every few days for draining the main tanks and water trap tanks, and once every other paint job on the desiccant to me isn't "ridiculous." I quit draining the pre-filter, QC-3, and ball valve drains because there was never any moisture in them.

I don't know what you mean by "let me know how long your compressor lasts with that setup." Please explain why you think this will shorten the life of my compressors.

Tell you what, I'll put my humidity gauge in a container and run compressed air through it to see what the RH is. That's less anecdotal and more scientific.

Yea a seperare refrigate system to cool the lines gradually. All you did was try to throw everything together in some funny contraption

Nate is correct and his design is sound. If you get the air to cool below the dew point, it will condense. Air coming out of a compressor head is very hot and saturated with water, so the dew point is very high. Even a small drop in temp, like through the condenser, will cause the water vapor to condense and collect. Active refrigeration will help, but it's not a requirement.

Like he said, it works. Not sure why you are arguing against it.

You know the dew point at which water is seperated from the air is almost freezing tempatures? Hence on industrial air dryer system have a Seperate refrigeration system.
His contraption does none of this

You're kidding, right?

http://www.calculator.net/dew-point-calculator.html

Give it a shot. Air temp coming out of pump head at 175 degrees F, and 70% relative humidity. Tell me what the dew point is.