So finally something I know a little bit about. I work in instrumentation and controls in a large food processing plant, well more in the information side of things now, but that’s my history. Yes, it’s definitely a good idea to drain your compressor on a regular basis. So one, yes it can cause rust in the tank and weaken it. If it gets weak enough, it will explode, though more likely it will tear and leak horribly, but explode is a good way to scare you into maintenance. And two, even if you have a filter and a separator (I’m sure no one really has a true drier here, but it’s possible) then there’s the possibility of carrying water over into your spray. Again, it’s probably a low possibility, but those of you living in humid climates that don’t drain their compressors, it’s more likely to happen.
The upshot is really that it’s a job that takes less than a minute to do, and the upside benefits far outweigh the cost in time. How often you do it really depends on the load on your compressor, but it’s such a simple, short duration job, why not do it every day?You take care of your equipment so it lasts longer. It’s safer to run. And, you don’t run the risk of funky stuff happening to your spray because of water. Think of all the things that people would consider silly that you do to ensure that your product comes out looking as pretty as possible, why not do some of the little things for the equipment the helps you get there?