PSA is the abbreviation of Pressure Swing Adsorption, which is a technology commonly used for oxygen production. PSA selectively adsorbs components in the gas through adsorbent materials to achieve separation of gas mixtures. 

PSA oxygen generator usually consists of two adsorbers (Adsorber) and a gas distribution system. The process gas (usually air) is introduced into the adsorption tank via a compressor. The adsorption tank is filled with an adsorbent, usually a specially designed molecular sieve. Under pressure, oxygen molecules are selectively captured by the adsorbent, while other gases, such as nitrogen, pass through the adsorption canister. 

When an adsorption tank is saturated with oxygen, the pressure swing process begins. The gas distribution system switches the pressure, directs the inlet air source to another adsorption tank, and simultaneously releases the gas in the saturated adsorption tank. In this way, the adsorption tank switches between adsorption and desorption to achieve continuous oxygen production. 

The adsorption tank on the side where the process is interrupted will reduce the pressure by releasing the adsorbed gas, so that the adsorbent can once again be used to adsorb oxygen. The entire process is cyclical to continuously provide high-purity oxygen. 

The capacity of PSA oxygen concentrators can vary depending on the needs of the specific application. Its capacity is usually expressed in terms of the flow of oxygen produced per hour, either in cubic meters or standard cubic feet. The capacity of oxygen concentrators can range from a few cubic meters to thousands of cubic meters to meet the needs of different places and industries.