Mark Mandell - Gone Round In New Jersey
and be prepared to lay out some real coin. Link will give you options.

McMaster also sells an air-actuated auto drain for your tank for $50. I've had one on my I-R for years will good results. I also used copper piping, line drains, and reverse loops for each air station. However, if you're complaint is water vapor during continuous use, the refrigerated dryers are going to be your only real option.