OXYGEN CONCENTRATOR WITH BEDS' DUTY CYCLE CONTROL AND SELF-TEST

摘要

A method of controlling performance of an oxygen concentrator having a first molecular sieve bed which is operated over successive control periods accord ing to a duty cycle for alternately pressurizing and flushing the first molecular sie ve bed and a second molecular sieve bed which is operated over the successive control per iodsaccording to a reciprocal of the duty cycle for alte rnately flushing and pressuring the second molecular sieve bed, the method comprising the steps of adjusting the duty cycle and the reciprocal duty cycle during every second one of the successiv e control periods to prolong the pressurizing relative to the flushing of the first mo lecular sieve bed and to prolong the flushing relative to the pressurizing of the second m olecular sieve bed, thereby degrading performance of the oxygen concentrator for redu cingconcentration of oxygen producing by the oxygen conc entrator; and adjusting the duty cycle and the reciprocal duty cycle during remaining control periods to prol ong the flushing relative to the pressurizing of the first molecular sieve bed and t o prolong the pressurizing relative to the flushing of the second molecular sieve bed, suc h that water vapor is purged from the first and second molecular sieve beds after pressur izing thereof. A further aspect of the present inventionis the provision of a pres sure-swing adsorption (PSA) subsystem performance check. This test is performed as part of a maintenance BIT (Built-In-Test) function. After verifying that the oxygen se nsoraccuracy 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 t o within specification (i.e. concentration limit above a predetermined level - such a s 50%).