Abstract: In a system for determining the state of each of a plurality of bi-state devices located remotely from a central station, a group of resonant circuits is connected to a multi-frequency excitation source. A bi-state device is then connected to each resonant circuit. When a particular bi-state device is in one position and its corresponding resonant circuit is being excited by its resonant frequency, a maximum amplitude signal is produced by the resonant circuit. When the bi-state device is in the other position, a lesser amplitude signal is produced. The signal produced by each resonant circuit is fed to detection circuitry and in turn to display circuitry. Thus the state of each of the plurality of bi-state devices is indicated by the display circuitry.The two wire line in addition may serve as a transmission medium for a DC control signal used for controlling a remotely located process control valve or for controlling other final actuators.

Abstract: A system is disclosed for switching a load between two ac sources wherein no degree of synchronization therebetween is required and wherein the switching is accomplished with the use of two electro-mechanical relays each having a three pole, double throw contact arrangement. Furthermore, this load switching is accomplished without the production of any interpower currents between the two sources.

Abstract: A flowmeter for use in sanitary applications where the flowmeter possesses a member that intrudes into the process fluid. The flowmeter includes a round pipe and a flow obstruction element that is uniquely secured in the pipe wall section. A co-planar section having an aperture is formed in the pipe wall. The flow obstruction element which has an enlarged head at one end is inserted through the aperture into the interior of the pipe. The enlarged head has a flat outer surface and a flow contact surface that is flat in the section adjacent its perimeter. The head is positioned so that the section of its flow contact surface adjacent its flow contact surface perimeter is co-planar with the inner surface of the co-planar pipe wall section. The side surface of the head is bonded to the side surface circumscribing the aperture in the co-planar pipe wall section.

Abstract: An electro-pneumatic current-to-position transducer includes an electric motor having a permanent magnet for a stator and spring restrained coil pivotally suspended about the magnet for a rotor. An input current to the coil induces a mechanical rotation of the coil about the magnet which is proportional to the applied current. Fastened to the coil for rotary movement therewith is a flapper positioned to cover the nozzle of a pneumatic circuit. As current is applied to the coil, the flapper moves toward the nozzle thereby changing the back pressure in the pneumatic circuit. This change in pressure is amplified, then sensed by appropriate pressure-responsive devices and subsequently fed back to a control lever on which the nozzle is mounted, thereby repositioning the nozzle so as to maintain an essentially constant separation between the flapper and the nozzle.