Is there any reason why I shouldn't use my air compressor to pressure test and run cleaner and sanitizer through the lines instead of wasting CO2. I could rig up a corny disconnect to the compressor disconnect and set my compressor to 20lb output.
That's fine but you'll still want to fill it with a bit of CO2 before racking in.
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The only thing I can think of is the possibility of your compressor producing condensation and pumping it into the keg. You may get small amounts of compressor lube (oil) in there too. I wouldn't risk it. Unfiltered compressed air can be nasty, save it for your car tires.
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