Abstract: An expansion chamber is attached between two air compression stages of an air compressor or between an air compression stage and the air holding tank of the air compressor. The expansion chamber has a cylindrically shaped wall with top and bottom portions attached so as to define an enclosed inner chamber. The enclosed inner chamber may have one or more baffle plates located therein. Various designs of baffle plate arrangements provide different air circulating patterns within the expansion chamber. Since the expansion chamber is exposed to the ambient environment, the compressed air heated in the compression process is cooled down in the expansion chamber. This cooling down of the compressed air as well as the expansion of the compressed air as it circulates within the enclosed inner chamber causes any moisture suspended in the compressed air to drop out and go to the bottom of the expansion chamber.