Draining Air Compressors

Water simply does not appear in the tank, it gets there through the compression of the air and the subsquent cooling of the air in the tank, where the water condenses out. If the tank is pressurized and no air is being used from it, no additional water will appear in the tank, If it is run, water will condense. You can leave it sit for weeks pressurized and if you first drained the water, you will get no more (other than what you failed to drain the first time).

I have never bled down a tank when I didn't use it. My little 1-1/5 horse 12 gal Craftsman stays pressurized all the time (even though I no longer use it around the shop) and it has been kept pressurized for the past 35 years, nary a problem.

I leave my big two stage 80 gal pressurized and on, that way its ready when I need it. I use some air virtually every day, sometimes to blow something off, sometimes to inflate a tire, sometimes for some serious work.

Charles

One method is to simply attach a drain leg with a ball valve, either on the supply line or in the bottom of the tank. This gives the water a place to collect. Every few days you can crack the valve and let the water out.

Another consideration is the purchase of an air dryer to remove the water from the air. Refrigerated dryers lower the dewpoint to near freezing, while coalescing dryers take the dew point down as low as you can afford.

It is a matter of money, my friend. The dryer the air, the more expensive it is.

Having pressure in the tank means I can inflate a tire and not need to run the compressor at all. I like to go from a dry start as seldom as possible. I wonder how dry the cylinders are when you start the compressor after a few weeks of standing.