1) Cylinder oxygen is mainly used for oxygen-acetylene flame cutting or gas welding. If there is no remaining pressure in the oxygen cylinder, the acetylene gas may flow back into the oxygen cylinder. When filling oxygen next time, the gas The cylinder may explode. Therefore, during normal use, the oxygen is not allowed to be used up, and there should be residual pressure. If there is no residual pressure, it may not be a normal gas cylinder; 2) There is residual gas to facilitate the detection of suspicious gas. The media should be checked and confirmed before the bottle is filled with oxygen; 3) If there is no remaining pressure in the oxygen bottle, air is likely to enter the bottle when the bottle valve is opened or stored. The purity of the oxygen will be reduced the next time it is inflated. Affecting normal use. Therefore, in order to ensure the purity of oxygen in the oxygen cylinder and the safe use of the oxygen cylinder, there should be residual gas with a pressure of not less than 0.05MPa during use.