I’m sure draining an air compressor of any accumulated water is possibly one of the least-fun maintenance activities out there. I’m assuming also that most compressors have virtually no room to fit a bucket underneath the drainage port at the bottom of the tank, so you end up having to tilt the unit to drain, which means not all the water gets out.
I used a short piece of air hose (4’), a pair of 3/8 barb x 1/4” NPT fittings, a 1/4 NPT x 1/4 NPT close elbow, and a small 1/4” valve, and a couple hose clamps, assembled them, and added this “whip” to the bottom of the compressor, to replace the factory default drainage valve. This took about 20-30 minutes tops.
The result is that the air pressure in the tank will force all the water out and through the hose (even “uphill”), and it is now trivial to simply drain the tank into a bucket without rusty water splashing all over the floor.
Indeed, the ease of draining the tank now means I will do it more frequently (as I should have been doing all along), which should improve the life of my compressor.
-- Woodworking from an engineer's perspective