Abstract: An apparatus is disclosed for determining the concentration of a fluid. In one aspect of the invention an apparatus for detecting the ionic concentration of a fluid is provided. The ionic concentration detecting apparatus may include a resonance coil or other suitable receiver that arranged to be influence by the fluid being monitored. The resonance coil is driven by a high frequency signal having a frequency in the range of 10-100 MHz. A detector is provided to measure the losses experienced by the resonance coil. In another aspect of the invention, an ultrasonic based density detecting apparatus for detecting the density of the fluid is provided. The ionic concentration detecting device may be used in conjunction with the density determining device to provide concentration detecting capabilities for solutions having multiple constituents.

Abstract: A differential conductivity recirculation monitor quantitatively determines the degree of recirculation in a fistula by comparing the conductivity of blood entering the fistula to the conductivity of blood being withdrawn from the fistula. A discrete quantity of a high conductivity marker fluid is injected into the blood entering the fistula, altering the conductivity of the blood entering the fistula. The altered conductivity blood enters the fistula and, if recirculation is present, co-mingles with blood in the fistula, altering the conductivity of the blood in the fistula in proportion to the degree of recirculation. Blood withdrawn from the fistula has an altered conductivity related to the degree of recirculation. Quantitative values of the conductivity of the altered conductivity blood entering the fistula and the conductivity of the blood being withdrawn from the fistula are measured and a difference determined.

Abstract: A differential conductivity recirculation monitor quantitatively determines the degree of recirculation in a fistula by comparing the conductivity of blood entering the fistula to the conductivity of blood being withdrawn from the fistula. A discrete quantity of a high conductivity marker fluid is injected into the blood entering the fistula, altering the conductivity of the blood entering the fistula. The altered conductivity blood enters the fistula and, if recirculation is present, co-mingles with blood in the fistula, altering the conductivity of the blood ion the fistula in proportion to the degree of recirculation. Blood withdrawn from the fistula has an altered conductivity related to the degree of recirculation. Quantitative values of the conductivity of the altered conductivity blood entering the fistula and the conductivity of the blood being withdrawn from the fistula are measured and a difference determined.

Abstract: A differential conductivity recirculation monitor quantitatively determines the degree of recirculation in a fistula by comparing the conductivity of blood entering the fistula to the conductivity of blood being withdrawn from the fistula. A discrete quantity of a high conductivity marker fluid is injected into the blood entering the fistula, altering the conductivity of the blood entering the fistula. The altered conductivity blood enters the fistula and, if recirculation is present, co-mingles with blood in the fistula, altering the conductivity of the blood ion the fistula in proportion to the degree of recirculation. Blood withdrawn from the fistula has an altered conductivity related to the degree of recirculation. Quantitative values of the conductivity of the altered conductivity blood entering the fistula and the conductivity of the blood being withdrawn from the fistula are measured and a difference determined.

Abstract: A contactless method and apparatus for in-situ chemical etch monitoring of an etching process during etching of a workpiece with a wet chemical etchant are disclosed. The method comprises steps of providing at least two toroidal windings in the wet chemical etchant to be proximate to but not in contact with the workpiece; and monitoring an electrical characteristic between said at least two toroidal windings, wherein a prescribed change in the electrical characteristic is indicative of a prescribed condition of the etching process. Such a method and apparatus are particularly useful in a wet chemical etch station.

Abstract: A system for determining a property, such as conductivity, of a material in which a sensor provides a square wave sensor output signal the value if which is selected to the proper in response to a square wave driver signal. The sensor output signal is compared with a feedback signal to produce an error signal. A forward circuit responds to the error signal and provides an in-phase component thereof which is integrated to provide an integrated DC output signal. A feedback signal provides an in-phase square wave feedback signal the peak-to-peak amplitude of which has a precisely selected relationship with the integrated DC output signal for comparison with the square wave sensor output signal to reduce the error signal to zero. The integrated DC output signal can be digitized and suitably processed to provide a signal which represents the property of the material to a high degree of accuracy.

Abstract: An improved detector assembly of an electro-magnetic conduction-type conductivity meter includes a plastic housing member having a liquid sample flow path extending therethrough. An excitation transformer is mounted in a cavity of the housing member along with the detection transformer for respectively inducing a current flow and detecting a current flow in the liquid sample flow path. A porous electrode is positioned adjacent one of the transformers and insulated by hydrophilic paper so that the entrance of any fluid within the cavity can be detected.

Abstract: In an improved electromagnetic induction-type conductivity meter utilizing primary and secondary transformer coils about a liquid sample passageway, a resistance circuit having a conductive lead line extending also through the coils and parallel with the sample passageway is provided. The resistance circuit can be selectively opened and closed, and has the capacity to contribute to the measurement voltage detected on the detector coil when the primary coil is excited. The value of this additional resistance voltage can be used for calibration and monitoring the condition of the conductivity meter.

Abstract: The invention concerns a process for controlling and/ or distinguishing liquids used in the brewing industry. To distinguish water, rinse water, different kinds of beer, and various non-alcoholic drinks with the help of technical measuring devices, a measuring instrument for monitoring or distinguishing the conductivity of the liquid concerned by inductive measurement is used.

Abstract: To measure the electrical conductivity of a liquid, or the concentration of a solution, an insulated combination of two transformers each of which has an annular core is immersed in the liquid such that the two transformers are electromagnetically coupled by a coil of the liquid which passes through the center holes of the two transformers. By applying AC voltage to the primary winding of the first transformer a current that is proportional to the conductivity of the liquid flows in the liquid coil, and this current is represented by the output of the second transformer. On the second transformer a compensation winding is wound so as to negate magnetic flux produced by the flow of the current in the liquid coil.

Abstract: A salt analyzer is disclosed capable of measuring the conductivity of a saline solution when either contact or non-contact probes are used. In particular, the salt analyzer employs circuitry capable of switchably measuring the various electrical parameters necessary for determining the conductivity of a solution when either contact or non contact probes are used.

Abstract: An improved detector assembly with an electromagnetic induction-type conductivity meter is provided with a pair of housing members forming a first liquid sample flow path at a central location, and a second liquid sample flow path on their outer circumference. An excitation coil and a detection coil extend about the first liquid sample path, while the second liquid sample flow path interconnects with the first liquid sample flow path both upstream and downstream of the respective coils. The second liquid sample flow path can substantially extend about the coils so that a relatively large induction current can be generated and measured as representative of the liquid sample.

Abstract: In accordance with the present invention an apparatus is provided for use with a developer container adapted to retain a quantity of developer material, the developer material including varying concentrations of magnetic carrier material and toner material. The toner concentration sensing apparatus comprises a device for generating a magnetic field within the developer container. The apparatus further comprises a device for controlling the generating device to selectively generate the magnetic field within the developer container, wherein a preselected portion of the developer material is compressed by the magnetic field and a signal is generated across the generating device, the signal across the generating device varying as a function of the concentration of the toner.

Abstract: An electrodeless conductivity measuring cell having three toroids. In one arrangement, the three toroids are stacked together wherein the center toroid is used for sensing and the two outer toroids are the drive toroids. Alternatively, the center toroid may be used as the drive coil and the outer toroids used as sense coils. Washer-shaped, grounded discs are placed between the outer toroids and the center toroid to provide for improved noise rejection. A method of validating the fluid conductivity measurement of such a measuring cell. The fluid conductivity is measured with a three-cell configuration, and then it is measured with a two-cell configuration. If the conductivity is observed to be the same, the cells are likely functioning normally. If fluid leaks into the cell cavity, the measurement of conductivity will change.

Abstract: An electromagnetic conductivity meter comprises a core; a primary coil wound around the core; an alternating power source for applying an alternating voltage having a given frequency to the primary coil to excite the core; a tube wound around the core through which a liquid to be measured flows; induction current detecting means disposed at the opposite ends of tube; and an operational means for determining the conductivity of the liquid to be measured from a value of the induction current detected by the induction current detection means.

Abstract: An inductive conductivity sensor is immersed in a liquid to measure its conductivity. The sensor comprises a transducer for generating a changing magnetic field and for inductively measuring an electric current induced in the liquid by the changing magnetic field. The transducer has an external surface facing the liquid. A elastic membrane separates the external surface from the liquid. The elastic membrane is periodically inflated and deflated to deform its outer shape and thereby remove deposits formed on the membrane.

Abstract: Apparatus for measuring the electrical impedance of low conductivity samples, and particularly microbial suspensions, has a coil surrounding a tubular sample container. A capacitive pick-up on the sample wall provides an input to a variable gain amplifier driving the coil. The resident frequency of the circuit is measured to provide an indication of sample conductivity.

Abstract: An apparatus for measuring the flow rate of electrically conductive liquids includes two coils disposed in succession as seen in the flow direction of a liquid. The coils are switched in alternation as a primary and a secondary coil. One of the coils is excited with an alternating current as the primary coil, and voltage induced by the excitation in the other of the coils as the secondary coil is measured.

Abstract: A method of investigating the condition of biological particles, in particular the fraction of viable cells in a bacteria population involves applying a voltage and monitoring the voltage induced by magnetic induction in a detector coil. The applied voltage is of a variable frequency alternating voltage and is preferably induced in the medium through a drive coil.

Abstract: An electrodeless apparatus for determining a function of the electrical charge condition in a flowable liquid media containing electrical charge influencing species comprising a tubular flow path member, the flow path member having electrically insulating walls, an open end and a closed end, the flow path being so disposed that it may be substantially filled with the liquid, a reciprocating member whose outer wall is electrically insulating disposed within the flow path member, the reciprocating member having a transverse cross-sectional configuration such that the reciprocating member fits adjacent but spaced from the electrically insulating walls of the flow path member, an annulus for admitting predetermined amounts of flowable material to the flow path member, a sensor disposed on the non-wetted side of the flow path member for developing a signal proportional to a desired ion activity by electrostatic or inductive coupling, and means coupled to said sensor for amplifying any electrical signal induced acr

Abstract: A method of investigating the condition of biological particles, in particular the fraction of viable cells in a bacteria population involves applying a voltage and monitoring the voltage induced by magnetic induction in a detector coil. The applied voltage is of a variable frequency alternating voltage and is preferably induced in the medium through a drive coil.

Abstract: An apparatus for measuring the resistance in a closed loop electrical circuit without breaking or otherwise disturbing the circuit includes a detachable connector for joining the measuring apparatus to a closed circuit. The connector is linked to a circuit that induces, through the detachable connector, an electrical current in the circuit whose resistance is to be measured and then detects and displays the resistance of the tested circuit.

Abstract: A cell for remotely sensing conductivity of a fluid passing through it, the cell having an inlet and an outlet and two fluid paths between the two, thereby defining a fluid loop, an excitation transformer comprising a first toroidal core having a hole through it and wire turns around it, the core encompassing a portion of the fluid loop therein, and a sensing transformer comprising a second toroidal core having a hole through it and wire turns around it, the core encompassing a portion of the fluid loop, the cores being coplanar to thereby reduce leakage between the transformers.

Abstract: A dialysis machine has control circuit which detects changes in input water temperature and compensates the water heater. The control circuit detects changes in the conductivity of the dialysate concentrate and compensates the concentrate pump. Changes in supply voltage are detected and the outputs of the several sensors and the inputs to the pumps and heater comensated. The control circuit periodically calibrates the blood leak detector. In each of the feedback loops which service the heater and each of the pumps, the control circuit varies both the loop response time and the loop gain to compensate for changes in the dialysate flow rate. The resolution of the D/A converters which drive the pumps are enhanced by the control circuit by time modulating the LSB of the respective digital drive value. If any of the several sensed operating conditions varies significantly from the expected value, the control circuit terminates dialysis.

Abstract: The invention includes a method and apparatus for controlling the concentration of wash water in a ware washing machine. A preferred ware washing machine (10) includes a reservoir (11) for holding wash water, a normally closed valve (17) for directing clean water to a dry detergent supply (13), an electrodeless conductivity cell (12) for monitoring the conductivity of the ware washing solution, and a controller for activating the normally closed valve (15) in response to the difference between the measured concentration and the actual concentration. A preferred concentration controller includes an adjustable amplifier (48) which provides an amplified concentration signal which is equal to a reference signal when the concentration of the solution is equal to the desired concentration.

Abstract: Apparatus for measuring the electrical conductivity of a subject comprises a coil for producing a substantially uniform magnetic field within a predetermined volume and a transport assembly for causing relative movement between the subject and the predetermined volume so as to move at least portions of the subject into and out of the volume. A measuring circuit is coupled with the coil for measuring the electrical conductivity thereacross and a control circuit causes the measuring circuit to measure the electrical conductivity across the coil a plurality of times during movement of the subject relative to the volume so as to obtain a plurality of measurements of the electrical conductivity across the coil with different portions of the subject within the volume.

Abstract: An induction voidmeter for detecting voids in a conductive fluid may comprise: a four arm bridge circuit having two adjustable circuit elements connected as opposite arms of said bridge circuit, an input branch, and an output branch; two induction coils, bifilarly wound together, connected as the remaining two opposing arms of said bridge circuit and positioned such that the conductive fluid passes through said coils; applying an AC excitation signal to said input branch; and detecting the output signal generated in response to said excitation signal across said output branch. The induction coils may be located outside or inside a non-magnetic pipe containing the conductive fluid.

Abstract: Disclosed is an inductance detector for detecting boundaries between and characteristics of at least two adjoining substances having different characteristics, such as impedance, wherein a coil assembly, which is energized by an alternating current, is electrically coupled to a detector for detecting at least changes in impedance of the coil assembly caused by the boundary proceeding into and through the coil assembly.

Abstract: A test apparatus is provided for measuring the proportion of at least one constituent in a sample of material, which constituent bears a known relationship to the electrical conductivity of the sample. The test apparatus comprises a sensor including both a receptacle for receiving a sample of material and a field producing coil for producing an electromagnetic field within the receptacle. The coil is also designed confining said electromagnetic field to a predetermined, fixed volume within the receptacle and for producing a substantially constant magnitude electromagnetic field throughout this predetermined, fixed volume. A monitoring circuit is coupled with the sensor and is responsive thereto for producing an output signal which bears a predetermined relationship with the real impedance of the sensor and therefore with the conductivity of the sample.

Abstract: A system for assessing the effectiveness of a water softener or comparable liquid-processing apparatus whose effectiveness is related to the difference between the electrical conductivity of the liquid supplied to the apparatus and the electrical conductivity of the liquid that has passed through the apparatus includes two inductance loop conductivity sensors excited by a common signal generator. The outputs of the sensors, which typically include unwanted quadrature components, are applied directly to the inputs of a differential amplifier. The resulting difference signal is then applied to a detector that is gated by the common excitation signal, so as to produce a detected signal that is substantially unaffected by the unwanted quadrature components. In a preferred embodiment, each of the inductance loop conductivity sensors includes two electrodes connected by a conductor that links two toroids.

Abstract: A device for measuring local electric conductivity of plasma, comprising a probe, which is kinematically coupled to a drive mechanism and has a series circuit including an inductive sensor, a measuring oscillator, and a detector having one output coupled, via an optoelectronic converter, to a differential stage having a switch and a memory member. An output of the differential stage is coupled to one input of a measurement recording unit having another input coupled to a unit for feeding commands which is electrically coupled to an electropneumatic control unit accommodating air valves of drive mechanisms of the probe and calibration crystal, the air valve being coupled to pneumatic cylinders of the drive mechanisms by means of flexible bases made of an insulating material.

Abstract: A paraffin monitor includes a pulse source periodically providing pulses. Apparatus, adapted to be immersed in a medium having paraffin, provides an output signal in response to each pulse in accordance with a paraffin film grown on said apparatus while the apparatus is immersed in the medium.

Abstract: A monitor which is capable of measuring accurately the water content in percent by volume of an oil and brine mixture, where the water content is 80% or more, includes a housing which is adapted to be connected to a pipe through which the oil and brine mixture is flowing so that the oil and brine mixture flows through a portion of the housing. A sensor is mounted within the housing so that the sensor is suspended in the flowing oil and brine mixture. The sensor provides a signal corresponding to the percent by volume of water in the oil and brine mixture, even when percent by volume of water is 80% or more, in response to an excitation voltage from a source. Indicating apparatus provides an indication of the percent by volume of the water in the oil and brine mixture in accordance with the signal from the sensor.

Abstract: A hydrocarbon detection system is provided for use in a subsea hydrocarbon production installation which includes production tree assemblies, an electro-hydraulic control module located on the sea floor and remote from the production trees, cable assemblies interconnecting the control module with the production trees through magnetic coupling devices. A pair of inductive elements are electrically coupled by the surrounding sea water. Displacement of the conductive sea water by escaping hydrocarbons affects the coupling between the inductive elements to produce a hydrocarbon-presence-responsive output signal. The inductive elements are resonated within a selected frequency range by capacitors coupled with a primary inductor coil by auxiliary windings on a common core element. An excitation signal sweeps over the selected frequency range at a rate effective to produce a peak detected signal at the resonant frequency.

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.