Abstract: A method of communication between RFID devices that includes mutually authenticating the RFID devices is disclosed. Once mutual authentication is completed, one or more encrypted messages based on the encryption scheme can be exchanged between the RFID devices.

Abstract: A double valve having inlet, outlet, and exhaust ports maintains an outlet pressure below one percent of inlet pressure during a faulted state while maintaining a relatively small exhaust for reduced overall valve size. Crossover passages receive inlet pressure through main crossover poppets when the respective valve units are not in a deactuated position. When the valve units are in a deactuated position, then the crossover passages receive inlet pressure through respective bypass passages whose flow rate can be controlled independently from the size of the crossover poppets. The use of bypass passages provides particular benefits for double valves for non-press applications which have a ratio of exhaust flow coefficient to inlet flow coefficient that is less than about 2.5.

Abstract: A double valve having inlet, outlet, and exhaust ports maintains an outlet pressure below one percent of inlet pressure during a faulted state while maintaining a relatively small exhaust for reduced overall valve size. Crossover passages receive inlet pressure through main crossover poppets when the respective valve units are not in a deactuated position. When the valve units are in a deactuated position, then the crossover passages receive inlet pressure through respective bypass passages whose flow rate can be controlled independently from the size of the crossover poppets. The use of bypass passages provides particular benefits for double valves for non-press applications which have a ratio of exhaust flow coefficient to inlet flow coefficient that is less than about 2.5.

Abstract: A control-reliable lockout valve system has an inlet port for coupling to a source of pressurized fluid and an outlet port for coupling to a downstream fluid-actuated device. A double valve unit includes a pair of valve elements each controllably moving between a respective actuated position and a deactuated position to control a first flow path between the inlet port and the outlet port in response to a pilot pressure applied to the valve elements. The first flow path provides the pressurized fluid to the outlet port only if both of the valve elements are in the respective actuated positions. The double valve unit further includes an exhaust port, and the valve elements control a second flow path for coupling the outlet port to the exhaust port unless both of the valve elements are in the respective actuated positions.

Abstract: The redundant valve system 10 of the preferred embodiment includes a first valve unit 12 and a second valve unit 14. The redundant valve system 10 is preferably used to connect a source 16 to a destination 18 and to connect the destination 18 to a reservoir 20. The first valve unit 12 and the second valve unit 14 are coupled to control fluid flow such that fluid flow is allowed in only one of two given directions at any given time, either from the source 16 to the destination 18 or from the destination 18 to the reservoir 20.