Abstract: Signal-processing apparatus for use with industrial instrumentation systems and the like, and comprising a memory to maintain a signal level for long time periods without drift. An input signal level is translated into the positioning of a movable member, through the use of an actuator motor controlled by the input signal and a position feedback signal. A friction device is coupled to the movable member to hold it in any given position, thereby to serve as a memory for the input signal level. The friction device comprises a thin vane-like element which is secured to the movable member and disposed in the air-gap of a permanent magnet. The air-gap also includes a mass of tiny magnetizable particles which, under the influence of the magnetic field, engage the surfaces of the vane-like element to develop a frictional restraining force.

Abstract: An industrial process control system for use with complex processes having many variables to be controlled.The system includes a CRT screen on which any of a series of predetermined displays can be presented to the process operator.The displays are arranged in hierarchical fashion, from plant summary information down to detailed data for individual process loops.The operator's console includes a variable function keyboard the keys of which perform functions determined by the particular displays being presented on the CRT.The CRT display includes symbols positionally correlated with the keys and which identify the key functions for the corresponding display.The operator is enabled to control the display and the process through use of the keyboard controller with the display presentations.

Abstract: A distributed, electronic process control system is disclosed having a plurality of remotely located stations interacting to control a complex industrial process. The stations communicate via a process communication link which supports secure, multi-master communication. The link provides a transparent medium of exchange for the secure transfer of process status and control information among the stations, such that each station may initiate and control system communication for a predetermined time period.

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 float is disclosed for use in tank gauging systems of the type having a vertically supported guide. The float includes a donut-shaped body member adapted to be positioned about the guide to ride freely with the liquid surface. A discharged tube is positioned concentrically with the body member by a number of support members. The discharge tube is positioned below the liquid surface and acts as a discharge electrode to maintain the path of least resistance for an electrostatic discharge of the float below the liquid surface.

Abstract: An electric force motor includes two movable and independently actuatable coils energized by a single magnetic circuit. Air gaps are formed at respective ends of a tubular permanent magnet between a core of magnetically permeable material mounted within the magnet and pole pieces attached to opposite ends of the magnet. Such a configuration thus establishes a serial magnetic circuit connecting the magnet and the core through each of the air gaps. The two coils, each positioned within the respective air gaps, receive independent electrical input signals to develop corresponding output forces. Interactions between each coil that would tend to affect accuracy are minimized by choosing a magnet of high coercivity and by limiting the amount of input current applied to each coil.

Abstract: A pressure measuring instrument of the vibrating-wire type comprising an elongate base on which is pivotally mounted an elongate lever parallel to the base. A vibratory wire in the form of a very thin flat ribbon of tungsten is held tautly between the lever and the base. A pair of bellows are supported on the base, on opposite sides of the pivot mounting for the lever, and apply a torque to the lever proportional to differential pressure. Counterbalance means are provided to prevent errors with changes in spatial orientation of the instrument. The lever support-structure is formed of a composite of elements providing a match of temperature expansion characteristics with the vibratory wire. An overrange protection mechanism prevents the application of excessive force to the wire.

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 electrodeless conductivity measuring system of the type employing a spaced pair of toroidal ferromagnetic cores, in which anomalies in the permeance of the cores is alleviated by the use of non-permeable shields of conductive material.

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.

Abstract: A data transmission system comprising a transmitter producing a high-frequency carrier modulated with data and swept in a repetitive time pattern over a wide frequency range. The modulation of the carrier is so controlled that a characteristic of the data signal modulation has a predetermined relationship with respect to the repetitive sweep time pattern. The system receiver comprises a narrow-band IF channel coupled to the output of a mixer arranged to receive the incoming swept-carrier signal and a correspondingly-swept local oscillator signal. The sweep control signal for the local oscillator is developed by a circuit coupled to the mixer output and responsive to the data modulation on the IF signal.

Abstract: A differential-pressure measuring instrument comprising a main body assembly with a pair of diaphragms each subject to a respective fluid pressure. The diaphragms enclose a sealed chamber containing a fill-liquid surrounding a non-magnetic vibratable wire which is tensioned in accordance with the applied differential pressure. A magnetic field passes transversely through the wire, and electrical current is supplied to the wire by electronic circuit means to produce a vibratory force on the wire as a result of interaction between the electrical current and the magnetic field.

Abstract: An ultrasonic flowmeter of the upstream/downstream sonic propagation type includes two transducers mounted externally on the same side of a flow conduit. The transducers are coupled to respective sonic probes which transmit and receive acoustic pulses between the transducers through the fluid by "bouncing" the pulses off the opposite pipe wall. Additionally the meter maintains a smooth bore in the measurement region so that the acoustic pulses are refracted at the probe/fluid interface and hence propagate along a sonic path that varies depending on the sonic velocities within the fluid and the probe. An acoustic path of known length is included within at least one of the probes along which a portion of the generated acoustic pulses propagates, thereby providing for a third sonic measurement which represents the transmit time in the probe.

Abstract: An industrial process recording instrument includes a roll chart cassette assembly that is readily removable from the instrument to accommodate replacement of the chart record. The replacement chart record is furnished on a supply roll insertable in one place of the cassette, while the lead end of the chart record is fixedly presecured to a take-up roll insertable in another place of the cassette, in such disposition that the longitudinal axis of the chart record is exactly perpendicular to the axis of the take-up roll. Thus the roll chart can be easily installed while the cassette is being hand-held in near-perfect alignment, thereby effectively minimizing the possibility of paper jams as the chart record is fed along the cassette.

Abstract: A universal module serves as the basis for creating a plurality of different embodiments of electrical display stations. The universal module is adapted to be connected to remotely located process control instrumentation from which it may receive and to which it may transmit analog and digital signals. The different embodiments are created by connecting to the universal module a selected combination of components such as status indicators, switches and signal adjusting devices. The universal module includes a micro-processor system having a central processing unit, a clock circuit and a non-volatile type of program storage unit with an address provided for each different embodiment. An embodiment selector provides the interconnection between the components connected to an embodiment and the circuits of the universal module and activates the address for the embodiment.

Abstract: In a spectrometer, an internal reflectance crystal having opposed internally reflecting surfaces extending between light-entrance and light-exit end surfaces is illuminated by a light source through a slit. The beam of light from the slit is reflected from a spherical mirror illuminated off-axis to form first and second astigmatic images of the slit. The tangential image, having a distorted (elongated or extended) height, is formed at the entrance surface of the internal reflectance crystal. The width of the tangential image matches the width of the entrance surface. The sagittal image is formed at the exit surface of the internal reflectance crystal. The width of the sagittal image, which would be distorted (extended) absent the internal reflectance crystal, is limited by the internally reflecting surfaces of the crystal. Thus, there is substantially no loss of radiant energy through the length of the crystal.

Abstract: A liquid filled differential pressure transmitter includes a metallic measurement diaphragm within a pressure chamber and a pair of isolation diaphragms sealing the chamber from the process fluid which serve to transmit the applied pressure signals to the measurement diaphragm. The isolation diaphragms bottom against mating back-up surfaces to limit deflection of the diaphragm during overrange pressure conditions. An electrically conductive liquid fills the chamber so that measurable electrical resistances are established through the liquid between the measurement diaphragm and a pair of electrodes adjacent thereto formed on opposite walls of the chamber. As the measurement diaphragm deflects in response to applied pressure signals, the electrical resistance between the diaphragm and each of the electrodes changes providing an output signal which is a function of the applied differential pressure.

Abstract: A pneumatic control instrument includes a nozzle-flapper system having improved dynamic response characteristics under vibrational conditions. A light-mass, compliant flapper having a high natural frequency covers the nozzle and serves to cushion the impact of the nozzle striking the flapper by moving at the same amplitude of vibration as the nozzle so as to precisely track the nozzle over a wide range of vibrational frequencies and amplitudes.

Abstract: A differential-pressure measuring instrument comprising a main body assembly with a pair of diaphragms each subject to a respective fluid pressure. The diaphragms enclose a sealed chamber containing a fill-liquid surrounding a non-magnetic vibratable wire which is tensioned in accordance with the applied differential pressure. A magnetic field passes transversely through the wire, and electrical current is supplied to the wire by electronic circuit means to produce a vibratory force on the wire as a result of interaction between the electrical current and the magnetic field.