Oxygen concentrator with beds' duty cycle control and self-test

Abstract

A method of controlling an oxygen concentrator having a first sieve bed operated over successive control periods according to a duty cycle for alternately pressurizing and flushing the first sieve bed and a second sieve bed operated over the successive control periods according to a reciprocal of the duty cycle is disclosed. The duty cycle and the reciprocal duty cycle are adjusted during every second one of the successive control periods to change the pressurizing relative to the flushing of the first sieve bed and to change the flushing relative to the pressurizing of the second sieve bed, for reducing concentration of oxygen produced. The duty cycle and the reciprocal duty cycle are adjusted during remaining control periods to change the flushing relative to the pressurizing of the first sieve bed and to change the pressurizing relative to the flushing of the second sieve bed, such that water vapor is purged from the first and second sieve beds after pressurizing thereof. A pressure-swing adsorption (PSA) subsystem performance check is disclosed. This test is performed as part of a maintenance BIT (Built-In-Test) function. After verifying that the oxygen sensor accuracy is acceptable using prior art techniques, a set of bleed valves are opened to load the oxygen concentrator at a specific flow. The oxygen concentration is then checked via the sensor to determine whether the PSA subsystem is operating to within a predetermined concentration level.