How often do you drain your air compressor?

I'm guilty! My compressor came out of my Plastics Plant some 25 or so years ago. 5HP single phase devilbiss that we had in a shack in the parking lot to run our air feeders. My maintenance guy neglected to put the air filter back at one point and it seized up from sucking dust from the parking lot. I had originally installed it with an electric valve to blow the tank off every weekend when shut down after 24/7 Monday to Friday midnight. That he'd also failed to maintain as well.

I had to replace it one weekend and simply pulled it out and replaced it with a new one, a 15HP 3 phase to cover expansion. I took the old one home. I was poking around the shop one day and gave the belts a pull and it moved, so I hooked it up and have been using it ever since. It's out in the hangar on top of my washroom and I have a 1" air hose line running all the way to the shop so I don't have to hear it run. In the Winter I plug a ceramic heater in that's pointed at the pressure switch so it will blow off properly. I can't remember the last time I drained the goo out of her, but one day I'm sure I'll find parts of that 39 year old gem scattered around the hangar. At least it's 9' up....