sizing dessicant dryer for spray finishing

[Andy Pratt]

I am setting up a spray area (new to this) and I'm trying to decide how to manage airborne moisture from the compressor. I will already have a liquid water/oil separator, so this just applies to dessicant dryers.

What is the most cost effective/convenient type/size of dessicant dryer for spraying finishes?

I already have a large (1 gal) nearly new wall-mount-type dessicant dryer from another adventure and I am weighing whether to sell it on ebay or use it for my spray setup. I could only get $100-150 so it is not worth doing this unless I would be replacing it with a much smaller version (refillable tiny dryer at the gun for example), or their is a compelling advantage to an at-the-gun smaller system, even if it costs more in the long run.

So, if most guys end up with a wall mount dryer that is 8oz-2qt anyway, I'll just keep the gallon one I have and use it. If everyone is using at-the-gun inline disposables (or refillables if that is available), for a good reason I would sell this and switch to those.

I will be using a gas compressor outside the shop to power the system, but is it likely that I will switch to an electric compressor in the (dehumidified) shop in the near future, if that helps. I'm in upstate NY where it isn't humid too often, but we do get some fairly humid days once in a while in the summer so I need to be ready for that. I do not have any hard piping for air lines, it is all flex hose.

Thanks,
Andy

[Steve Jenkins]

Andy, I can't speak to the dessicant dryer but you may not need one. If you can cool the air before the gun the water will condense out and you won't get a wet misty spray. There are several ways to do this. Several years ago I purchased an after cooler from grainger. It looks kind of like a car radiator with a fan mounted on it. the air passes through the piping in the aftercooler and is cooled by the fan. Another way I have seen is to make a zigzag run of piping up a wall. the ambient air around the piping will cool the air in the pipe. A couple years ago I added an 80 gallon storage tank to my system to slow the cycling of the compressor and since then I haven't had to run the aftercooler at all. I use a pneumatic sander which requires 12-15 cfm and no problems. Using an airgun to blow off dust also presents no problems.