A gas separation device for separating oxygen gas from air includes a compressor; a concentrator; a measurement mechanism; and a flow control mechanism that includes a valve assembly for providing fluid flow control, the valve assembly having a motor; a valve body; and a plunger within the valve body...http://www.google.de/patents/US7517385?utm_source=gb-gplus-sharePatent US7517385 - Gas separation device and method of use
