Question What is removed when an air tank is drained? Answers Water and oil Ammonia Wood Chlorine Explanation In an air brake system, the air storage tanks are equipped with drains to allow water and compressor oil to be removed. The water and oil can damage the brakes if left to accumulate in the system. Take a FREE Practice Test Now This questions appears in the following tests: Florida Knowledge Test Class A , Colorado Knowledge Test Class B , Kansas Knowledge Test Class B , Maryland Air Brakes , New York Air Brakes , Wisconsin Air Brakes ,