Bottled gas is available in both gaseous and liquid form. Oxygen, nitrogen, argon, hydrogen, helium and air are gaseous gases, acetylene is gaseous and dissolved in acetone, liquid ammonia, carbon dioxide and laughing gas are liquid gases.

To check whether the gaseous gas conforms to the full bottle, the common inspection method is to test the display pressure of the cylinder with the pressure gauge.

To check whether the liquid gas conforms to the full bottle, the common inspection method is to weigh the weight in pounds. The "W" symbol shown on the cylinder seal refers to the weight of the cylinder. If acetylene is 4-5kg/bottle, its weighing method: the total weight minus the weight of the cylinder, and so on; Acetylene is not the basis or standard for filling the bottle to the pressure shown in the pressure-relief device (table).