What are sieve canisters in oxygen concentrators?

Q: What are sieve canisters in oxygen concentrators?

A: Sieve canisters are the main component of oxygen concentrators. Their function is to purify room air by adsorbing the nitrogen in the air while allowing oxygen to pass through and collect in a chamber for delivery to the patient.

How sieve canisters work

·       Air intake: Room air is pulled into an oxygen concentrator through filters and passes through an air compressor before being delivered to one of two sieve canisters.

·       Air compression: The compressor pressurizes the air in one sieve canister to about 20 psi.

·       Zeolite: The sieve canisters contain an organic material called zeolite, or molecular sieve. Under pressure, this porous material has the capacity to adsorb nitrogen while allowing oxygen to pass through. Because room air is about 78% nitrogen and 21% oxygen, the air that passes through the sieve canister becomes more oxygen pure (usually 87% - 96% O2) as it leaves the nitrogen behind.

·       Product tank: When the air in a sieve canister has been purified, it passes to a product tank to await delivery to the patient. The compressor switches to the second sieve canister to begin the purifying process while purging the nitrogen from the first canister. This process repeats continuously to deliver purified oxygen to the patient.

The process of pressurizing air and using zeolite to separate chemical components is called pressure swing adsorption. This process was invented in the 1950s by C. W. Skarstrom as an alternative to heating materials until they liquified. While the process has many applications, the purification of oxygen has proven to be a major medical advancement for individuals with significant lung disease.

REFERENCES

How sieve canisters work: https://hengyeinc.com/oxygen-concentrator-sieves-hengye/

Psi needed for zeolite to work: https://blog.novomof.com/blog/high-efficiency-oxygen-concentrators

Invention of pressure swing adsorption: https://www.chemistryworld.com/opinion/skarstroms-separator/4013737.article