Oxygen generators are also called air separation equipment (air separation equipment for short). There are many types of oxygen generators, and there are many different types according to different classification methods. According to different product purity, it can be divided into devices that produce high-purity oxygen with an oxygen purity of more than 99.2%; devices that produce low-purity oxygen (also called process oxygen) with an oxygen purity of about 95%; devices that produce rich oxygen with a purity of less than 35%. Oxygen (also called liquefied air) device. According to different product types, it can be divided into single-high product devices that simply produce high-purity oxygen; double-high product devices that simultaneously produce high-purity oxygen and high-purity nitrogen; and argon extraction devices or full extraction devices that are attached to extract rare gases. According to the form of the product, it can be divided into devices that produce gaseous products; devices that produce liquid products; and devices that produce both gaseous and liquid products. According to the number of products, it can be divided into small equipment with a capacity of less than 800m3/h; medium equipment with a capacity of 1000 to 6000m3/h; large equipment with a capacity of more than 10000m3/h. According to different separation methods, it can be divided into low-temperature distillation method; molecular sieve adsorption method and membrane permeation method. According to the working pressure, it can be divided into high-pressure devices with a pressure of 10.0 to 20.0MPa; medium-pressure devices with a working pressure of 1.0 to 5.0MPa; and full low-pressure devices with a pressure of 0.5 to 0.6MPa. The classification method is artificial, and there can be other classification methods.