The Stovebolt Forums Forums The Shop Area Paint and Body Shop Air filters/dryers

I am coming closer to getting my paintbooth ready for painting and was wanting advice on what to use for filter/drying of my compressed air. I was thinking of plumbing my shop air over to the booth where I would have a filter/dryer. I was thinking of punching through the wall and putting a quick disconnect on the inside then using a very flexible whip for easy maneuvering inside the booth. I guess the question is how much is enough? I also saw there is a small filter/dryer that could be put just ahead of the spray gun. Should I use one or both? All advice is appreciated!

By the way yesterday I picked up my car from the blaster which was also green primed, some acid wash prep. It looks beautiful, can't wait to get after it. Dave

I use a small in-line throwaway filter just in front of my gun. That's all I have other than a filter separator right at the compressor discharge. I haven't gotten to finish paint yet, so haven't worried about having perfectly dry air. I may add air dryer capacity when I get to finsh paint.
A friend built an air dryer using fintube like what is used on baseboard heating. He ran about 20 feet of the stuff in-line right after the compressor with a drain trap at the bottom of the rack. The idea behind that is to cool the air as much as possible, then drain the water out. The colder the air gets, the more water can be wrung out of it. Another important thing is to have the piping sloped to points where moisture it can be drained.

I made a water seperator for my shop. The theory is making the air bend helps remove the moisture. Dead end traps with valves gives a place for the moisture to accumulate and then get drained out of the system.
This setup has the inlet at the bottom and works it's way to the top. The final loop has a trap and a drain then goes high before coming down to the air filters.

I have a trap at the compressor, then 30' past, a long coil of hose with a drain on the last loop. Cools at those loops. Then I run about 75' of hose to the other side of my house where I have my "booth" tent. At that point, one more trap, then my dry hose that I spray with. On my gun(s), I have a fisheye filter, sometimes. Haven't had water contamination issues for some time now.

My friend's setup is similar to Wayne's, except his has vertical runs. If the runs were made out of fintube it would cool the air quicker.

Also, sloping the horizontal runs in the direction of airflow would help direct the condensed water to the traps, so compressor connected at the top would be a bit more efficient. Then the takeoff for the hose would be above the final water trap. An auto drain trap for the water at the bottom of your drip leg would be the icing on the cake, so you wouldn't have to remember to drain the drip leg.

Here's a pic of my friend's setup.

I made one of these. look up "The Copper Coil Air Dryer/Compressor Aftercooler DIY " on Youtube. It worked well, you fill it with ice. - painted my truck in the September Florida humidity with no issues. I did have a the desiccant snake after it just in case and 30 ft of hose before it.

Clever solutions! I live in Oregon where it rains occasionally so I also had trouble with water in my air lines, especially when painting. I discovered that when the compressed air leaves the gun nozzle that it expands and gets colder resulting in condensation. My solution was to fill about 3' of schedule 40 PVC pipe with reusable desiccant that I can remove by removing the pipe caps on the PVC. The desiccant can then be rejuvenated by placing on a cookie sheet in an oven at 175 degrees F for approximately 30 minutes. I also use a HF "final filter" at the gun just in case.

Good idea.

Being lazy, I'd probably build something like that with the air line coming in from the side down low, and out the side up high with screw caps on top and bottom. Then Just unscrew the caps to replace the dessicant without having to disturb the piping. If you built it out of clear tubing, you could tell when the dessicant needed to be changed, also. I don't know if clear tubing is rated for compressed air though. Most recommendations are to avoid any type of plastic pipe for compressed air, although there are some that are specifically rated for it. There's a danger of rupture, and with all that stored energy that could be dangerous.

I've also read that PVC should not be used for compressed air so I chose to put it after the regulator to limit any potential damage. This also allows the air to expand and cool lowering its temperature and making the desiccant work better. You could also place the dryer behind the tank or some other large object to minimize potential damage or place it in a section of 4" stove pipe. I have the regulator set to 60PSI (my compressor tops out at 125 PSI) and I use another regulator at the gun. As you suggested, the air enters the bottom of the dryer and exits out the top. I also installed small screens at the input and output to keep the desiccant out of the air lines.