Abstract: An instrument for developing at a central control station a signal responsive to the value of a process condition occurring at a field measurement station remote from the central control station wherein a resonant device is used as the instrument basic sensor element. The resonant device which is located at the field station may be excited by either a voltage pulse or a continuous wave. In a particular aspect, the output measurement signal of the instrument is solely dependent upon the value of a desired measured variable, which is representative of a process condition, and is independent of other variables. The resonant device is coupled to excitation and detection circuitry located at the central control station and produces in the detection circuitry when excited with a pulse of energy first and second signals, one of which is dependent upon the desired measured variable and a second variable and the other dependent upon at least the second variable.

Abstract: Control of multiple distillation columns for producing anhydrous alcohol suitable for blending with gasoline to produce gasohol. The distillation process involves production of a first-stage distillate containing a predetermined amount of water, followed by azeotropic distillation in the presence of a hydrocarbon entrainer to strip the distillate of its water content, leaving anhydrous alcohol as a bottom product. Tight controls are present during first-stage distillate production to hold its proof at an optimum value derived at through material balance calculations to minimize energy consumption for the overall system. Control over the dehydrating stage is accomplished by a combination of ratio control to regulate and maintain the proper proportion of the entrainer and temperature control to regulate within the column the actual inventory of entrainer.

Abstract: A compact temperature-control unit for use with gas chromatographs. The unit includes a highly insulated enclosure with a removable lid having a gas chromatograph column wound on a thin-walled core fixedly positioned within the enclosure. Provisions are included for inserting a temperature-control module within the cavity formed by the core to achieve temperature control. A variety of different modules can be used to alter the desired control point.

Abstract: A process control system includes two digital controllers each capable of exercising direct digital control over the process. One of the controllers is selected to be on-control, the other serving as a backup. A separate data buffer memory connected to both controllers stores the most recent static and dynamic data base of the on-control controller which is transferred to the backup controller. In the event of failure or other loss of service, the backup automatically acquires control with an up-to-date data base resulting in a smooth transition. Provisions are also included to have the backup controller examine the health of the on-control unit before deciding whether or not to accept the data buffer contents thereby reducing the likelihood of corrupted data being fed to the backup.

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 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: A focusing solar collector which utilizes an elongated parabolic shaped mirror made from a sheet of drapable material so that when draped in a catenary like curved configuration, the sun's rays may be focused on a linear target which is axially aligned with the axis of the mirror. Means are provided for adjusting the angle of the drape of the catenary like curve in order to maintain the focus of the sun's rays on the linear target as the relative diurnal position of the sun to the collector changes. The optimum catenary like curve for the range of the drape angles involved is achieved by using a non-linear distribution of weight along the cross-section of the draped mirror material.

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 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.

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: 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 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 receiver for a carrier that is swept in frequency in a predetermined manner over a bandwidth comprises frequency tracking with continuous self-synchronization. The frequency tracking permits the carrier to be filtered by a narrowband filter. The filtered carrier is then fed to a frequency discriminator to produce an error signal. A highly-selective phase-locked loop synchronizes only to the desired component of the error signal in frequency and in phase. The output of the phase-locked loop, after appropriate shaping, is the control signal for tracking synchronously the incoming wave. The output data are obtained at detection after the narrowband filtering.

Abstract: A magnetic flowmeter includes a field coil extending along the longitudinal axis of a flow conduit for generating an integral magnetic field concentrically located about the coil and perpendicular to the flow. An inner electrode surrounds the coil, and the conduit itself is used as the other electrode, thereby providing a large surface-area electrode for sensing flow induced voltages. High current (over 20 amperes), very short duration (less than 10 millisecond) pulses energize the field coil whose inductance is low enough to permit electrode output voltages to be read within a few milliseconds after the magnetic field current pulse is turned on. The measured output voltage comprises a short-pulse, flow induced component proportional to flow rate, superimposed on a d-c voltage approximately equal to the galvanic potential at the electrodes.