Oxygen Generators

Oxygen VSA (Vacuum Swing Adsorption), Oxygen VPSA (Vacuum Pressure Swing Adsorption) and Oxygen PSA (Pressure Swing Adsorption) are processes used to separate oxygen from other gases in the air. These processes typically consists of two adsorption columns in parallel, in batch sequence switched by automatically controlled valves. Each column includes a zeolite-type adsorption layer that separates the nitrogen from the air so that the desired component oxygen remains.

VSA and VPSA technology use a blower to feed air to the oxygen generator to produce oxygen. However, here lies the main difference between VSA and VPSA. In VSA the typical delivery pressure of the blower is a maximum 200-300 mBar (3-4 psi). For VPSA, the typical delivery pressure of the blower lies between 300-1000 mBar (4-15 psi). The consequence is that the VPSA technology can delivery higher oxygen pressure.

To be able to remove the captured nitrogen molecules, both VSA and VPSA technologies use a vacuum pump to remove the captured nitrogen in a process step we call regeneration. In both technologies, vacuum pressure levels are the same.

Therefore, the main difference between Oxygen VSA and Oxygen VPSA is that VSA operates at lower blower pressure and VPSA operates at higher blower pressure. Also, VSA is typically used for lower purity applications, while VPSA can produce higher purity oxygen.

Then what is PSA? PSA is similar to VPSA but simplified without a vacuum pump. Instead of using a blower, a compressor is used to deliver feed air of around 7 Bar (100 psi) to the zeolite bed. Once the zeolite bed in PSA is saturated with captured nitrogen, the pressure is reduced to atmospheric pressure where the nitrogen automatically desorbs, without the help of a vacuum pump, leaving behind pure oxygen. Due to the use of a compressor instead of a blower, typical oxygen delivery pressure is 3.5 Bar (50 psi).