VSA Technology
VSA stands for “Vacuum Swing Adsorption”. Oxygen is separated from a mixture of gases using a single, low-pressurized vessel filled with zeolite. The system then switches to a vacuum pump so the zeolite can regenerate.
What is Pressure Swing Adsorption?
PSA uses prepared ambient air as a source to produce medical-grade oxygen. Ambient air contains multiple gases: typically 21% oxygen, 78% nitrogen, 0.9% argon and 0.1% rare gases. PSA uses pressure and a molecular sieve to separate the oxygen. The resulting product gas is oxygen, argon and a little nitrogen which meets the pharmacopeia requirement for Oxygen 93. It then vents pressure to atmosphere to regenerate the molecular sieve.
Vacuum
VSA concentrators typically are comprised of a single vessel filled with zeolite media. This vessel is pressurized with low maximum pressures and then evacuated (hence Vacuum Swing).
Swing
The oxygen is concentrating during the pressurization part of the ‘swing cycle’. The zeolite is regenerating through the vacuum part of the ‘swing cycle’. The production is therefore intermittent.
Adsorption
As the air flows through the vessel, the zeolite holds back the nitrogen molecules, water vapor and pollutants. Only oxygen and argon molecules are allowed to flow through the vessel and out to the system. A second vessel stores the oxygen produced.
How does it work?
Low pressure, adsorption and a ‘vacuum swing’
Air is compressed by a low-pressure blower and passed into a single, concentrating vessel. As the air flows through, the zeolite acts as a molecular sieve, allowing only oxygen and argon molecules to flow through the vessel and out to the system. Gradually, the nitrogen saturates the zeolite. If nothing were done, the concentration of oxygen would fall off, but before this can happen the concentrating vessel is isolated from the storage vessel and the blower reverses, drawing a vacuum.
The vacuum: regenerating
The blower pulls the accumulated nitrogen, water vapor and other gases off the zeolite, clearing out the necessary space in the zeolite matrix for another cycle.
