How does an oxygen concentrator work?

Oxygen concentrators operate on the principle of pressure swing adsorption of atmospheric nitrogen onto zeolite materials. At high pressure, nitrogen sticks to the surface of the zeolite. Because the zeolite is extremely porous, it has a very large surface area and can adsorb large volumes of gas. At low pressure the nitrogen is released.

An oxygen concentrator has two cylinders filled with zeolite pellets. Air is compressed to a few times normal atmospheric pressure (typically 20 psi/138 kPa gauge, or 2.36 atmospheres absolute) and passed through the zeolite bed. The bed adsorbs the nitrogen, leaving nearly-pure oxygen (plus small amounts of argon, CO₂, water vapor and other minor atmospheric components) in the output.

The zeolite becomes saturated within a few seconds, at which point the compressed air is fed to the second cylinder while the first is vented to ambient pressure, and the nitrogen escapes. When the second cylinder is saturated, the compressor switches back to the now-available first, and the cycle repeats.

Many units cycled with a period of about 20 seconds, and supply up to 5 liters per minute of 90+% oxygen. Since about 1999, units capable of supplying up to 10 lpm have been available

Overview of Oxygen Concentrators

An oxygen concentrator is a medical instrument that provides oxygen therapy to patients with respiratory illnesses. Oxygen concentrators administer oxygen that is purer than the oxygen in the ambient air. Oxygen concentrators have become significantly more popular than compressed oxygen tanks. Unlike oxygen tanks, oxygen concentrators do not run the risk of leaking and causing explosions or fires. For this reason, oxygen concentrators are safer for use in emergency and military situations, where the probability of accidents is high. Oxygen concentrators also are used in some industrial applications, though their primary use is for medical treatment.

Mechanics of Oxygen Concentrators

Ambient air consists of approximately 21 percent oxygen and 78 percent nitrogen. Oxygen concentrators suck in ambient air and filter out the nitrogen, leaving pure oxygen. Oxygen concentrators contain two Zeolite towers that are filled with aluminum silicate. Room air is compressed and pumped into these towers, where the aluminum silicate absorbs the nitrogen. The nitrogen is subsequently vented out of the Zeolite towers, and the pure oxygen is pumped into a storage tank where it is held until needed by the patient. There are stationary and mobile oxygen concentrators, both of which run off of conventional power sources as well as batteries. Oxygen concentrators typically cost around $800, although many individuals and medical practices lease the devices from manufacturers.