Powder Coat Part 6 – Air Filters and Dryers

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The air you supply to the blasting cabinet and the powder coat equipment has to be clean and dry. When blasting, you do not want water moisture to come out of the sand blast gun and start rusting the piece you are cleaning before you get it out of the cabinet. Moisture in the air can also cause the blast gun to clog.

Just like compressors there are different levels and kinds of dryers. The dryers are rated by the CFM they can handle and the amount of water and particulates they remove from the air. To be honest, I do not have a lot of knowledge about these different types of dryers.

> Desiccant dryers range in size and how they operate. The typical one purchased for home use is inexpensive and requires the desiccant to be changed or dried periodically. They do an excellent job as long as the desiccant is in good condition. You can dry desiccant by putting it in a regular oven for a 15-30 minutes at 150F to 250F depending on type of desiccant.

> Water Separators work pretty well removing 98 % of the water and do some filtration as well.  There is no element that needs to be changed and some have automatic drains so maintenance is quite low. I ran a water separator and then a desiccant dry in series for a long time with great success.

> Refrigerated Dryers operate by taking the hot wet air coming out of the air compressor and cooling it to about 3 degrees Celsius. All the water vapor that was in the air condenses into water. The water is then removed from the compressed air by a water-trap. After that, the cold air is re-heated to room temperature. They are simple in design and need very little maintenance. If you buy a quality one and install it properly, it’s basically set-and-forget. I was able to purchase a used one and cannot say enough good things about it.

I still have the water separator in the pipe circuit but there is never any water in it to drain.

Finally, one more small topic on air supply. Just as important as the compressor and the filtration is the plumbing system itself. There are lots of information sources on this and I will let you do a Google search.

Do not use PVC pipe. PVC pipe can explode with sharp shards flying across the shop when used for compressed air. I used thick wall copper pipe. You really should use Black Iron pipe but it is expensive.

There is a right way and a wrong way to lay out your plumbing.