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Just got a new craftsman air compressor (33 gal). I have read that it is important to "break in" the unit by running it with the pressurized chamber open (so that there is no load on the motor). How long do I do leave it running in this state? Is there anything else you would recommend I do?

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I would hook it up to a set of bagpipes, and leave it running until the neighbours call the police. – Chris Cudmore Dec 2 '10 at 16:45
@chris: Do you have to dress the compressor in a kilt to do this? – Doresoom Dec 2 '10 at 17:55

Not so sure about needing to break in the unit, but if it is an oiled compressor then make sure you change the oil after the first 10 hours (or about that). Also if you do go ahead and break in the unit, some compressors have a duty cycle that is less than 100% (running 100% of the time). The compressor I have (Sears Craftsman 3 gal., 1 hp, Horizontal Tank) has a 50% duty cycle so it should not run more than 30 minutes in any one hour.

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Answering a little late, but the instructions that came with my 20 gal. oil-free Husky say to run the compressor for 10 minutes with outlet and drain open. Times may vary depending on compressor size, lubrication style, etc., so check your owners manual.

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+1 for "check the owners manual" – TomG Sep 30 '12 at 1:08

A new compressor should be broken in before being used for work. The compressor should be run for 30 minutes with the unloader valve locked open to seat the rings. The unloader valve can then be reset for normal compressor operation. The oil should be changed after the first few hours of operation. Check to see if there is any specific requirements; if there are no special requirements, use a quality synthetic oil.

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