Compositions and methods for adsorption of a species (e.g., ammonia, water, a halogen) comprising metal organic frameworks (MOFs) are generally provided. In some embodiments, a MOF comprises a plurality of metal ions, each coordinated with at least one ligand comprising at least two unsaturated N-heterocyclic aromatic groups arranged about an organic core.

A respiratory protection filter includes filtration media. The filtration media includes an iron-doped manganese oxide material having an average pore size (BJH method) in a range from 1 to 4 nm and a surface area (BET) of at least 300 m.sup.2/g, or at least 350 m.sup.2/g, or at least 400 m.sup.2/g.

A portable oxygen concentrator designed for medical use where the sieve beds, adsorbers, are designed to be replaced by a patient. The concentrator is designed so that the beds are at least partially exposed to the outside of the system and can be easily released by a simple user-friendly mechanism. Replacement beds may be installed easily by patients, and all gas seals will function properly after installation.

A pressure swing adsorption (PSA) system and methods for controlling each PSA cycle performed by the PSA system to produce oxygen enriched gas during productive portions of a user breathing cycle, and to cease production of oxygen enriched gas during non-productive portions of the user breathing cycle, is provided. The PSA system synchronizes PSA cycle phases including adsorption and desorption phases with a user's individual inhalation and exhalation phases, on a breath by breath basis, such that each PSA cycle can be dynamically varied from a succeeding PSA cycle, in real time in response to variations in the user's breathing cycle. An oxygen delivery device including a breathing cycle sensor provides breathing cycle inputs to a controller for use with at least one algorithm to detect breathing flow phases during each user breath, and to synchronize each PSA cycle to the user's breathing flow phases, on a breath-by-breath basis.

An oxygen concentrator comprises a product tank that is fluidly coupled to at least one sieve bed, and a product gas accumulator tank that is fluidly coupled to the product tank via a first conduit and to an outlet port via a second conduit, wherein the first conduit and the second conduit are disposed to allow at least a portion of product gas to flow from the product tank to the outlet port.

A pressure swing adsorption (PSA) system and methods for controlling each PSA cycle performed by the PSA system to produce oxygen enriched gas during productive portions of a user breathing cycle, and to cease production of oxygen enriched gas during non-productive portions of the user breathing cycle, is provided. The PSA system synchronizes PSA cycle phases including adsorption and desorption phases with a user's individual inhalation and exhalation phases, on a breath by breath basis, such that each PSA cycle can be dynamically varied from a succeeding PSA cycle, in real time in response to variations in the user's breathing cycle. An oxygen delivery device including a breathing cycle sensor provides breathing cycle inputs to a controller for use with at least one algorithm to detect breathing flow phases during each user breath, and to synchronize each PSA cycle to the user's breathing flow phases, on a breath-by-breath basis.

A battery retaining system for a portable oxygen concentrator includes a first rail configured to receive a first slide of a battery, a second rail configured to receive a second slide of the battery, the second rail being spaced apart from the first rail so as to form a channel configured to receive the battery, and a flexible stiffening mechanism configured to impart a biasing force on a surface of the battery when the battery is received within the channel. The flexible stiffening mechanism includes a protrusion projecting from the first rail at least partially towards the second rail and a slit positioned behind the protrusion and configured to facilitate travel of the protrusion fore and aft.

An adsorber for a gas concentrator includes an adsorbent material having adsorbent particles and a vessel housing the adsorbent material. The vessel includes a vessel wall having a non-circular cross section and at least one stiffening support. A combination of a thickness of the vessel wall and a stiffness of the stiffening support is sufficient to limit deformation of the vessel wall to at least one of less than 0.1 mm and less than 25% of an average diameter of the adsorbent particles under a pressure swing of at least 30 psi within the vessel.

A method of operating a compressor system includes determining an efficiency of a compressor configured to operate at a plurality of output flow settings, including one or more of measuring, calibrating, calculating, or modeling motor efficiency over a range of supply voltage and pulse width modulation duty cycle combinations, each combination including a supply voltage of a plurality of supply voltages and a pulse width modulation duty cycle of a plurality of pulse width modulation duty cycles. The method further includes selecting a supply voltage and a pulse width modulation duty cycle for use at at least one output flow setting of the plurality of output flow settings based on the determined efficiency of the compressor, generating the selected supply voltage by maintaining, reducing, or increasing a nominal supply voltage, and applying the selected pulse width modulation duty cycle.

A compressor assembly for a portable oxygen concentrator includes a first compressor chamber having a first connector, a second compressor chamber having a second connector, and a tube having a first end having a first connection interface configured to connect to the first connector and a second end having a second connection interface configured to connect to the second connector. The first connection interface is shaped to maintain the connection between the first connector and the first connection interface in a fixed orientation and the second connection interface is shaped to maintain the connection between the second connector and the second connection interface in a fixed orientation. One or more of the first connector, the second connector, and the tube are compliant.