An empty cylinder of UN 1002 Air compressed can be shipped as non-dangerous goods. The word: EMPTY must be shown on the AWB. All hazard labels must be removed from the cylinder. Reference is DGR 3.2,2,4.1 where it says Gases of Div. 2.2 are not subject to these regulations if they are transported under a pressure less than 200kPa at 20℃ and are not liquefied or refrigerated liquefied gas.