Abstract: The present invention relates to detecting the state of a slide block positioned in a linear valve and using the position of the slide block to predict the health of a linear valve and provide information to a controller/monitor. An operator is provided with information before failure occurrence to allow preventative maintenance of the linear valve. The linear valve is constructed with two canister ports and a vent port. The slide block can be constructed to block the two canister ports and vent port simultaneously. The system can control the position of the block, when provided with position information, hence, using the slide block as a shutoff valve. The typical slide valve can be used as an integral slide shutoff valve, reducing system complexity and reducing system weight, which is critical to airborne applications.

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.