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 paraffin monitor includes a pair of probes which are immersed in a medium having paraffin contained therein. A circuit is connected to the probes which provides an output voltage. The characteristics of the electric circuit changes over a period of time, causing a corresponding change in the voltage output, in accordance with a change in the amount of paraffin on the probes.

Abstract: A compact, battery-powered water resistivity sensor measures the resistivity of water, sequentially compares the measured resistivity to a plurality of predetermined resistivities, and numerically displays that one of the plurality of predetermined resistivities approximating the measured resistivity. Preferably, the pair of electrodes consists of a pair of printed circuit electrodes disposed conveniently on the end face of an insulating nut extending, in fluid-tight fashion, into the tank of water. The sensor is powered by a battery, and includes circuitry for interrupting the supply of battery power to various circuit elements, the functions of which elements are no longer needed once the water resistivity is determined by the sensor. The sensor also includes temperature-sensitive compensation means responsive to changes in the water temperature for varying an input signal provided to the electrodes.

Abstract: Method and apparatus are disclosed for measuring and controlling the concentration of oxygen in a gas. A sensor (10) is provided having a zirconium dioxide wall (12). One side of the wall is exposed to a reference gas having a known oxygen concentration while the other side is exposed to a gas having the unknown oxygen concentration. An electrical potential is developed at the sensor output, where the magnitude of the potential is dependent upon the relative oxygen concentrations on either side of the sensor wall and the temperature of the wall. The reference gas is selected such that variations in the electrical potential due to temperature changes are minimized over the expected range of temperatures to which the sensor will be subjected during the oxygen concentration measurements and over the range of oxygen concentrations which must be measured.The sensor temperature is measured by measuring the resistance of the sensor, which varies directly with temperature.

Abstract: Circuitry is disclosed for measuring the quantity of total dissolved ionized salts in an undiluted aqueous sample. A bi-level power supply operating through a square wave generator and voltage follower creates a low amplitude AC signal at a predetermined level above a ground reference. The control voltage is applied through a conductivity probe assembly to two series connected operational amplifiers operating through a bridge assembly and meter movement to provide a reading of the total dissolved ionized salts in the sample as a function of their ionization characteristics.

Abstract: In every flow passage of milk sucked out from each quarter mamma through each teatcup, a trap is equipped. The electric conductivity of the milk is measured independently by means of electrodes equipped in each trap.The difference in value among quarter mammae is obtained by performing a subtraction between the minimum conductivity selected out among these traps and the other conductivity values.Said differential value is compared with predetermined reference values. The outputs of comparator circuits are divided into three groups. When the output of any one group is below a lower limit value, the milk which gives such output is indicated as normal. If the output is higher than an upper limit value, the milk is indicated as abnormal, and when intermediate these limits, an indication of quasi-abnormality is given. Especially for abnormal and quasi-abnormal milk a warning is given by sounding a buzzer.

Abstract: A method and apparatus wherein a sample of gas or fluid containing carbon dioxide in the form of dissolved carbon dioxide gas, bicarbonate ion, and/or carbonate ion is injected into an extraction chamber provided with an acid extracting fluid. A carbon dioxide-free gas stream is passed through the extraction chamber in order to carry the dissolved CO.sub.2 gas formed from bicarbonate and carbonate ions, as well as that already present, onto a spiral absorbing column, wherein a dilute alkaline solution absorbs the CO.sub.2 with a resulting change in electrical conductivity of the alkaline solution. The system disclosed provides electrical means for measuring the conductivity difference thus produced, means for conversion of this difference to an appropriately coded electrical signal, and means for providing a direct display of the sample concentration. Means are provided for indicating when a sample is being processed by the apparatus, and for holding the displayed concentration until manually re-set.

Abstract: Methods and apparatus for measuring electrical conductivity particularly but not solely for use in detecting mastitis in individual quarters of a cow's udder employ the cyclical charge and discharge of a capacitor (C1) through liquid in a conductivity cell (9), the cycle reversing on the potential applied to the capacitor (C1) reading a high reference potential and a low reference potential by applying the reference potentials to terminals (10,15) or sensing leads (32,33) of electronic devices (VC1, VC2) or (31) to cause operation of switches (SW1SW2) or (S1, S2) so that the variations in frequency are indications of conductivity of the cell (9). In one modification a reference conductance (30) is included in the circuit during charging of the capacitor (31) and the rate of the time periods of the cycle gives an indication of the conductance of the cell (9) in terms of the reference conductance (30).

Abstract: A system for measuring a parameter of a liquid sample, such as the hematocrit and an approximation of hemoglobin for a blood sample. The system basically comprises a hand-held instrument and a disposable sample card. The instrument accepts the disposable sample card, which is used for the one-time conveyance and application of a liquid sample, such as blood, to the instrument. The instrument has provision for digital displays for readouts. The disposable sample card is a micro-volume conductivity cell precision molded from plastic with built-in stainless steel electrodes. The instrument basically comprises an electronic portion for processing data obtained from the liquid sample on the sample card, a front-end mechanism for positioning the sample card within the instrument, and a digital display for displaying in eye-readable form the results of a parameter measurement made in the instrument.

Abstract: The conductivity cell consists of a first set of electrodes fixed rigidly to a second set of electrodes. Each set of electrodes has an insulating material support with an electrode well through it, and three spaced electrodes positioned sequentially within the well. In one embodiment, the support is a glass tube and the three electrodes are deposited on the inner surface of the glass tubes. In a further embodiment, the three electrodes are washer shaped conductive strips fixed within the electrode well and spaced by two washer shaped non-conductive strips also fixed within the electrode well. Each set of electrodes further includes a glass tubing fixed within the electrode well between each outer electrode and the outer end of the electrode well. In another embodiment, washer shaped electrodes are recessed in the wall of the electrode well such that the surface of the strips are flush with the electrode well surface.

Abstract: A simple, low cost test instrument for measuring effectiveness of a corrosion inhibiting film. It employs solid state integrated circuits and applies an AC signal across the film. The amplitude of the signal is less than that which would damage the film, and the electrical resistance is a measure of the inhibitor effectiveness.

Abstract: A circuit is provided for producing an electrical output signal representative of the conductivity of a sample of fluid in a chromatograph sample cell. A constant A.C. current source is connected to one of the electrodes in the conductivity cell and a change in the resistivity of the cell is measured to produce an A.C. signal which is then conditioned by a signal conditioner. The signal conditioner scales the AC signal and converts it to a D.C. signal representing the resistivity of the conductivity cell. The resistivity signal is supplied to dividing means which is operable for inverting the resistivity signal to provide a signal representative of the conductivity of the sample fluid. Conductivity values can be detected in both the sample conductivity cell and a reference conductivity cell to provide conductivity signals for both the sample cell and the reference cell.

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.