Many people think that you can use the smell method to distinguish， but in fact， the smell method for new oxygen cylinders filled with high purity oxygen is not very effective， because， filled with medical oxygen cylinders and filled with industrial oxygen cylinders in the beginning of the use of oxygen， through the human sense of smell is very difficult to find the difference.

But with the passage of time， the degree of rust and corrosion within the high-purity oxygen cylinder gradually deepened， slightly open the switch of the oxygen cylinder (the switch can not be opened too large)， can smell the strong sulfur， water rust， or acidic odour， it is very likely that it is not medical oxygen.

High-purity oxygen is used for industrial production and product processing of industrial gases， quality requirements are lower general requirements for the purity of 99% or more qualified. The filling procedure is not as strict as that of medical oxygen， and there are often water and other impurities mixed in and remaining in the oxygen cylinders. The water mixed in and remaining in the cylinders will lead to rusting on the inner wall of the cylinders， which will make the gas inside the cylinders with a peculiar odour.

At the same time， high-purity oxygen also exists in carbon monoxide， carbon dioxide， acetylene and other impurities that are extremely harmful to the human body， once the patient inhales too much， choking， coughing， crusting and other phenomena will occur， triggering or aggravating respiratory system diseases.