Can the auxiliary cylinder hold oxygen? Please go back to Asian cylinders. Is oxygen harmful to people?

In principle, argon cylinders cannot contain oxygen. First of all, when used by unsuspecting people, it may lead to extremely dangerous consequences. Second, the signs outside are different. Argon does not support combustion, and oxygen supports combustion. Third, it will make the existing oxygen purity insufficient. In addition, the thickness of the bottle wall varies with the density of standard temperature and pressure. Argon bottle has high density and thick wall. So try not to use argon to bottle oxygen, so as to avoid a big problem, and the bottling manufacturer will not allow it.