Abstract: A normal pH sensitive glass electrode is deactivated by exposure to thermal treatments at relatively high temperatures of approximately 190.degree. C. for predetermined periods of time until the nominal electrode sensitivity is reduced to very low levels such that the output potentials of such deactivated glass electrode approach the characteristics desired for a theoretically perfect reference electrode.Additionally, a method of forming a deactivated pH glass electrode including the steps of exposing a normal pH or other ion sensitive glass electrode to high temperatures in the order of 190.degree. C. or higher for predetermined periods of time is disclosed.

Abstract: An ion activity monitoring device is disclosed, having a semi-conductor device including an ion-sensitive field-effect transistor, for detecting the activity of ions in a liquid medium of interest, and a temperature sensor, for detecting the temperature of the liquid medium of interest, a constant current circuit for supplying a drain current of a particular value to the transistor, and a processing circuit for calculating the concentration of the ions in the liquid medium of interest. The drain current is of a value satisfying the relationship of .vertline.Id/.beta..vertline..ltoreq.0.10 volt.sup.2, wherein Id represents the drain current and .beta. represents the channel characteristic value of the ion-sensitive field-effect transistor. A method for operating the transistor is also disclosed.

Abstract: An improved system for the monitoring of pH of a liquid containing oil and water by directing the flow of at least a portion of the liquid into contact with the electrode of a pH meter for measuring the pH of the liquid, interrupting the flow of liquid to the electrode periodically, directing the flow of a washing solution into contact with the electrode to remove any depositions on the electrode, and then resuming the flow of the liquid into contact with the electrode to continue the monitoring of pH of the liquid without the need for manual removal and cleaning of the glass electrode.

Abstract: A combination pH/reference electrode is provided with the two electrochemical references being symetrically thermally insulated from the sensing membrane and being thermally adjacent each other. The portion of the pH fill buffer in contact with the inner surface of the sensing membrane is thermally insulated, as by KCl crystals, to rapidly equilibrate in temperatures with the sample solution.

Abstract: The present invention includes a system for mounting a sensor probe through the wall of a chemical vessel or other fluid container such that a sensing element can be located within. The system includes means for maintaining the sensing probe within the vessel in a fluid-tight, elevated temperature-resistant and corrosion-resistant seal. The system further includes provisions for removing, from the exterior of the reactor vessel, the sensing probe from the fixed sensing probe holder assembly which is within the interior of the reactor vessel. Further, means are included by which a sensing probe of an extended length which is mounted through the top of a chemical reactor vessel, can be inserted into and removed from the reaction vessel even with a low overhead situation above the uppermost portion of that reactor vessel.

Abstract: The clogging of junctions of electrochemical reference cells by contaminants is prevented by a triple junction design incorporating dual, independently operative flushing conduits. The first conduit flushes the exterior of the first junction and the exterior of the second junction, and the second conduit flushes the interior of the second junction and the exterior of the third junction. When the cell is used in-line on a chemical process stream, pressure equalizing means are employed between the stream and the standard electrode, of which the third junction is an element. Elevation of the exits of the flushing conduits above the junctions releases air from the cell which may collect at the junctions and impair the accuracy of the readings.

Abstract: A pH sensor includes a substrate formed of an electrically conductive carbon material. A hydrogen ion-sensitive layer is formed on the substrate surface. The layer is formed of an electrooxidation polymer of a nitrogen-containing aromatic compound selected from the group consisting of 1-aminopyrene and a mixture of 1-aminopyrene and pyridine.

Abstract: A pH measurement device includes working and reference electrodes. The working electrode has a linear electrically conductive substrate, at least a distal end surface of which consists of platinum, and a selective hydrogen ion permeable layer formed on the distal end face of the substrate. The reference electrode includes an electric conductor formed to be insulated from the working electrode and surrounding the working electrode, a polymer-silver (I) complex layer formed on the outer circumferential surface of the conductor, and an ion-conductive layer containing an anionic compound and formed on the complex layer. The pH of a solution is measured in accordance with a difference between a potential of the working electrode and that of the reference electrode.

Abstract: A transcutaneous blood carbon dioxide sensor together with a method for making such a sensor and for making electrodes used in the sensor. The sensor comprises a palladium/palladium oxide junction type electrode and a silver/silver halide junction type electrode applied to an electrically nonconductive substrate, partially coated with an insulative dielectric and partially coated with a polymeric membrane material including a bound electrolyte, the polymeric membrane material being permeable to carbon dioxide. The Pd/PD0 electrode was made cathodic prior to terminating the electro-oxidizing conditions.

Abstract: Rapid and accurate whole blood analysis measurements are made with analysis systems of the potentiometric type that employ restricted diffusion type liquid junctions where the whole blood sample is flowed past sensing electrode and liquid junction at a velocity of at least one centimeter per second during a data acquisition interval that is at least twenty-five milliseconds in duration.

Abstract: A method and apparatus for rapidly detecting toxicants via the use of a ft CO.sub.2 sensing cell and a second reference CO.sub.2 sensing cell, with each sensing cell including a first chamber and a second chamber, separated by a CO.sub.2 permeable membrane, and a pH sensor disposed in each of the second chambers. The method includes the step of placing distilled water in the first chamber of each cell, and allowing its dissolved CO.sub.2 to become equilibrated with the water in the second chamber, from which it is separated by the CO.sub.2 permeable membrane. Next, exact amounts of a microorganism and sugar are added to small dishes in the first chambers along with control vegetation for one dish and vegetation to be tested to the other dish. Then the first chambers are completely filled with distilled water and the dishes are agitated to facilitate a solution of microorganisms and sugar.

Abstract: Process and apparatus for directly measuring the ion strength of an electrolyte solution is disclosed. The pH value of the electrolyte is measured by means of a first measurement with a first indicator dependent on the ion strength and by means of a second measurement with a second indicator dependent on ion strength in a manner different from the first indicator whereby the ion strength is computed by means of the approximation ##EQU1## J=ion strength Jo=ion strength upon calibrationpH'(N)=pH value, measured with a first indicator N dependent on the ion strength (HPTS)pH'(X)=pH value, measured with a second indicator X dependent on the ion strength, the ion strength dependence of which is different from that of the first indicatorW(N)=valency of the first indicatorW(X)=valency of the second indicatorwith ##EQU2## The ion strengths of other ions and of unknown electrolyte may also be computed.

Abstract: An apparatus for monitoring ion concentrations in an aqueous solution comprises a plurality of electrodes insertable into the solution. At least two of the electrodes are ion-selective for particular ions. Each ion-selective electrode is electrically connected to a corresponding impedance buffer, which generates a low-impedance output signal having the same voltage as the electode. A plurality of operational amplifiers in full differential configuration is provided, each operational amplifier receiving a particular pair of output signals generated by the impedance buffers. Each differential amplifier generates an output signal indicating the potential difference between the impedance buffer output signals received as inputs by the differential amplifier.

Abstract: An optical fiber joint type ion-concentration measurement apparatus in which electrical signals which are detected by an ion selective electrode are transformed into optical signals which are transmitted to a receiving side of the apparatus by means of optical fibers. The detected signals from the electrode are frequency modulated by a voltage/frequency converter and the output of the voltage/frequency converter is used to control an electronic switch. The electronic switch controls a series circuit including a power source and a charging-discharging capacitor and a light emitting diode. The frequency modulated transformed detected signals therefore cause the light emitting diode to emit optical signals which are then transmitted by means of optical fibers. On the receiving end of the apparatus, the optical signals are transformed into electrical signals by a photo diode and then demodulated by a frequency/voltage converter to reproduce the original detected signals from the ion selective electrode.

Abstract: A method of measuring ion concentrations in solutions comprises using at least two ion sensitive test electrodes in the solution to be measured, the test electrodes having different sensitivities only in respect of the ion or ion mixture to be measured, setting the operating point of the test electrodes by means of at least one common reference electrode, and evaluating the signals of the test electrodes to produce a measurement result essentially independent of the properties of the reference and test electrodes which would interfere with accurate measurement.The invention also includes apparatus suitable for carrying out the method.

Abstract: An ion measuring device (pH meter) is adapted to store and discharge standardizing solution, as well as to provide measurements of the hydrogen or other ion concentrations of unknown samples; the device including a working electrode of known construction and a reference electrode adjacent to the working electrode; and further including at least one storage reservoir for containing a standardizing solution, and a measuring or standardizing chamber located at the lower end of the reservoir with means, preferably in the form of a valve, for permitting communication between the reservoir and standardizing chamber such that standardization and calibration can be carried out.

Abstract: A reference electrode (102), standard calibration solutions (72 and 76) and a sample solution (80) are all placed in liquid contact with one another and a reference solution (70). Contact between the reference solution (70), the sample (80) and the calibration solutions (72 and 76) is made through salt bridges (82, 74 and 78). A special conical shaped solution container (FIG. 5) having a porous plug or other salt bridge extending through the container wall at the apex provides special advantage.

Abstract: An ultrasonic streaming current detector for developing, on a continuous basis, an electric signal which is a function of the charge condition existing in a stream containing charged particles. The present invention has a cross shaped housing having a cross member and a longitudinal member containing a pump chamber having a reciprocating piston on a pair of signal generating electrodes. A fluid injection connection is provided to the base of the longtudinal member. The piston pumps a sample stream within the pump chamber, creating a reciprocating shear force against the sample stream, generating an electric signal across the electrodes. The generated signal is representative of the average electric charge of the suspended particles in the sample stream. To prevent buildup of sample particles in the pump chamber, which would bias the signal, a periodic wash backflow of a fluid is injected into the pump chamber, preferably at a point opposite the point of sample fluid injection.

Abstract: A pH sensor comprising a sleeve assembly having at least first and second spaces, a partition separating the two spaces from each other with a water tight seal, and a barrel including a flange, a reference electrode accommodated in the first space and including a liquid junction, a glass electrode having a sensor unit disposed adjacent to the liquid junction, liquid grounding means mounted adjacent to the liquid junction, and a cable disposed in the second space with a watertight seal, the cable being electrically connected to the reference electrode, glass electrode and liquid grounding means. The pH sensor can be used for continuous flow, immersion or submersion types of installations, and can be fabricated inexpensively and is easily maintained. The sensor unit of the pH sensor can be easily cleaned by a cleaning unit which includes a rotatable shaft to which is connected a vane and a brush at one end.

Abstract: An apparatus and method are disclosed for the continuous monitoring of pH in a fluid stream flowing at a low volumetric flow rate. The stream is directed through an enclosed conduit with a glass electrode sealed therein. The conduit wall facing the electrode has contour approximately complementary in shape to the sensing surface of the electrode with a narrow gap between the opposing surfaces through which the fluid passes, forcing rapid and uniform flow of the fluid over the electrode surface. Continuous operation is thereby permitted for extended time periods without substantial fouling of the surfaces.

Abstract: A method for determining the pH value of deionized cooling water in a system with a main loop and at least one parallel loop in which the electric conductivity of the cooling water in the main loop and the electric conductivity of the cooling water in the parallel loop behind an ion exchanger is measured and the H.sup.+ ion concentration is derived therefrom.

Abstract: A PH electrode is provided with an ISFET for generating a potential difference according to the PH value of an electrolyte to be measured, and includes a cell for driving the ISFET, so that the PH electrode can be used, as it is, with a conventional, potential difference type PH meter.

Abstract: A measuring electrode device comprises a pH electrode arranged within an outer casing and having a pH sensitive member in contact with an electrolyte housed in the outer casing. The electrolyte reacts with a predetermined gas in a liquid to be inspected and varies its pH. The pH sensitive member includes a semiconductor substrate and a pH sensitive membrane formed on the substrate and in contact with the electrolyte. The pH sensitive membrane is formed of at least one element selected from the group consisting of silicon nitride, aluminum oxide and tantalum pentoxide. A potential difference is produced between the pH sensitive membrane and the electrolyte in accordance with the variation of the pH of the electrolyte. Thus, a potential difference is produced between the pH electrode and a reference electrode according to the variation of the pH of the electrolyte.

Abstract: An indicating device for measuring instruments having a voltage-frequency converter for converting measurement signals expressed as voltage values into frequency signals with a frequency proportional to the voltage values, a counter for counting the frequencies of the frequency signals sent from the voltage-frequency converter and sending the counted number to an indicator for digitally indicating the measured values corresponding to the counted number. A switch is connected between the voltage-frequency converter and the counter, and a controller for holding the switch in the closed state only during a predetermined time is connected to the switch. Analog signals sent from the measuring device can be indicated digitally and the digital values indicated can be held by a simple, inexpensive and miniaturizable construction.

Abstract: An assembly for mounting a pH probe in a flowing solution, such as a sanitary sewer line, which prevents the sensitive glass portion of the probe from becoming coated with grease, oil, and other contaminants, whereby the probe gives reliable pH indication over an extended period of time. The pH probe assembly utilizes a special filter media and a timed back-rinse feature for flushing clear surface contaminants of the filter. The flushing liquid is of a known pH and is utilized to check performance of the probe.

Abstract: A device suitable for potentiometric analysis of liquid ions is disclosed, wherein a liquid transport member extending between and adjacent to two electrodes comprises two opposed surfaces spaced apart a distance to induce capillary flow of liquid between the surfaces.

Abstract: An electrode for measuring the pH of a liquid at high temperatures and pressures comprises a first hollow electrode formed of the ceramic which exhibits a pH-dependent potential thereacross and a second electrode provided with a porous ceramic junction. Two flexible-walled members are in fluid communication with the hollow interior of the two electrodes and are surrounded by a chamber whose pressure is kept substantially the same as that to which the electrodes are exposed. However, the chamber is thermally insulated from the hot solution whose pH is being measured. The interiors of the hollow electrodes and the flexible-walled members are filled with the same buffered solution and measuring electrodes are disposed within each of the flexible-walled members. The construction enables the measuring electrodes to be kept at substantially room temperature, thereby reducing chemical attack thereon and eliminates errors in potential measurement due to streaming and thermal diffusion potentials.

Abstract: A probe system is provided which may be removably installed in-line in a pressurized pipe line to determine the pH of the fluid flowing therethrough. The probe system comprises a mounting means exteriorly secured to the pipe line, a valve means in said mounting means and a cap means secured to the mounting means and having an opening therein. An elongated pH probe is inserted through said opening and is secured by said mounting means while the probe tip is disposed within the pipe line. The probe includes a transducer for converting the acidity of the fluid flowing through the pipe line to an electrical signal representing the acidity, and a smooth, adherent plastic coating is provided on said probe to define an elongated sheath with a uniform, round circumference. A sealing means seals against the sheath to prevent fluid flow past the cap means, said sealing means permitting movement of the sheath relative to said cap means upon installation and removal of the probe within the pipe line.

Abstract: A method and apparatus for the continuous monitoring of process stream chemical process. The apparatus includes a canister or reservoir with a sampling chamber having an inlet for the process stream in an upper portion of the canister and an outlet returning the sample to the process vessel. The inlet and outlet are offset from one another and sized to maintain a positive pressure within the sampling chamber so that a turbulent flow pattern through the sampling chamber is established. A measuring device such as an electrode assembly depends into the chamber within the canister and transmits a representative signal to a remote analytical instrument. Entrained gases are removed from the upper portion of the chamber via conduit and valve.

Abstract: A method and apparatus for measuring a chemical characteristic of a liquid such as its hydrogen ion activity or pH value. A disposable cassette having a reference and indicating electrode therein utilizes the same solution to first calibrate the device and then as an electrolytic bridge from the liquid sample to the reference electrode. The solution has the properties of a buffered pH and also provides a stable electrochemical environment around the reference electrode. In one embodiment, a volume of a liquid sample is placed into a capillary tube and the open end of the tube is then placed over the indicating electrode immersed in the solution. The electrical potential between the indicating electrode and the spaced reference electrode in the electrolyte solution provides a measurement of the pH value of the liquid when compared to the calibration potential previously measured without the liquid sample contacting the indicating electrode.

Abstract: A cell body having a pair of electrodes insulated from each other and adapted for direct immersion and use in commercial, laboratory, or industrial fluids or process streams, the cell being usable at temperatures below freezing and above the boiling point of water. The cell includes an insulated ultra pure antimony electrode and an insulated electrode of noble metal, the noble metal of the one electrode being immersed in the process stream as is the pure antimony electrode. The cell provides a self-contained solid state unit with the two electrodes adapted to measure pH in fluids or process streams containing solid mineral or ore particles, in acid, neutral or basic solutions of a wide range of temperatures and pressures, including vacuum applications and this system requires no external or internal reference or standard electrodes.

Abstract: Apparatus is disclosed for measuring the electrochemical activity of a liquid, for example, the hydrogen ion activity or pH value of blood. A disposable cartridge includes spaced indicating and reference electrodes which develop electrical properties as a function of the electrochemical activity. The cartridge carries a capsule containing an electrolyte solution. A machine for measuring the electrochemical activity includes a socket in a pivoting door for receiving the cartridge. When the door is pivoted into a closed position, the capsule is automatically crushed thereby covering the electrodes with the solution. The breaking of the capsule triggers an electronic measurement of the resultant electrical properties that develop between the two electrodes. This calibration factor is stored and used to compute the electrochemical characteristics of the sample when it is introduced into the cartridge to cover the indicating electrode.

Abstract: An ion sensor probe for constant monitoring of the pH level of a solution in a scrubbing system. The probe includes a tubular housing having a plug member inserted at one end thereof. The plug member supports an ion sensor cell and a reference cell in a side-by-side relationship. Each of the cells has one end exposed for contacting the solution. The plug member encloses the one end of the ion sensor cell to form a chamber which communicates with a bore in the plug member. A cleaning fluid of water and an acidic solution can be independently admitted into the chamber to cleanse the one end of the ion sensor cell. The probe is inserted into a well member shaped to receive the probe and having one end configured so as to permit only a portion of the solution to contact the ion sensor cell.

Abstract: An improved temperature-compensated ion measurement method and apparatus for use therein. The method comprises placing a probe in a solution whose ion level (for example, pH) is to be measured and measuring the A.C. resistance of the probe in a manner that does not adversely affect the simultaneous measurement of the probe's D.C. potential, and then driving from these two measurements the ion level of the solution corrected for its temperature.

Abstract: A simplified system for practical use in the measurement of specific ion concentrations. A probe for introduction into a fluid stream to measure the ion concentration thereof and said probe comprising an ion sensitive electrode for immersion in a fluid stream in combination with an annular elongated electrode having a noble metal, such as one of the platinum group of metals, on an end surface thereof for immersion in the fluid stream. The combination of the ion sensitive electrode, and the annular elongated electrode having an end thereof with the noble metal is placed in the fluid stream to be measured and is electrically connected to a measurement and/or indicating instruments.

Abstract: A circuit arrangement is disclosed for determining the end point in an amperometric titration, in which the current between a working electrode and a counter electrode is measured as a function of the total volume of the titration agent added in volume units. The working electrode is operated with a constant polarization voltage with respect to a reference electrode and a closed-loop control is provided for holding the polarization voltage prescribed between the working electrode and the reference electrode at a constant. The prescribed rated value voltage is compared to the actual value voltage identified between the working electrode and the reference electrodes. The reference value voltage is prescribed with the assistance of a reference value generator, the actual value voltage is identified in a high resistance manner with the assistance of an impedance transformer and the reference value/actual value deviation is compensated by way of a summing integrator.

Abstract: A glass pH measuring electrode is mounted in a piston that reciprocates in a chamber which is in fluid communication with a reference electrode. Intake and outlet lines to the chamber are controlled by valves. A drive means operates the piston and the valves to pull successive liquid samples into the chamber for measurement and then to discharge them. The drive means also controls two positive displacement pumps, one of which feeds controlled amounts of electrolyte past the reference electrode and the other feeds a bacterial sterilizing agent to the chamber. The electrolyte flow past the reference electrode and into the discharge flow from the chamber maintains open electrical communication with the chamber. A deformable body, preferably a bed of finely ground methyl methacrylate grit, in the chamber engages and cleans the glass electrode as the piston reciprocates.

Abstract: A self-cleaning apparatus (10) for the monitoring of pH in an effluent process stream (17) includes a sump pump (16) for sampling the effluent process stream (17), a housing (12) for supporting a pH electrode (13), and a cleansing assembly (15) for automatically cleansing the pH electrode (13) entirely powered by the impingement of the fluid process stream (17) upon the cleansing assembly (15). The housing (12) includes an electrode chamber (14) into which the pH electrode (13) extends. The electrode chamber (14) receives the effluent process stream (17) sample from the sump pump (16) and is also automatically, continuously cleansed by the cleansing assembly (15).

Abstract: A concentration of copper ions, a concentration of a reducing agent, a concentration of a complexing agent and a pH of a chemical copper plating solution are continuously detected all as potentials, and continuously controlled with a good accuracy.

Abstract: A method and apparatus for measuring a chemical characteristic of a liquid such as its hydrogen ion activity or pH value. A disposable cassette having a reference and indicating electrode therein utilizes the same solution to first calibrate the device and then as an electrolytic bridge from the liquid sample to the reference electrode. The solution has the properties of a buffered pH and also provides a stable electrochemical environment around the reference electrode. In one embodiment, a volume of a liquid sample is placed into a capillary tube and the open end of the tube is then placed over the indicating electrode immersed in the solution. The electrical potential between the indicating electrode and the spaced reference electrode in the electrolyte solution provides a measurement of the pH value of the liquid when compared to the calibration potential previously measured without the liquid sample contacting the indicating electrode.

Abstract: A portable self-calibrating pH meter particularly adapted for use by unskilled operators in adverse environment conditions is disclosed which has a minimum of operator controls while preventing operator errors and while providing effective and accurate pH measurement.

Abstract: An improved signal transmission apparatus of two-wire type is disclosed.

Abstract: A liquid testing kit for determining the pH value of a liquid body at various depths includes a pH tester and a liquid sampling container having a spring-hinged lid. The container is adapted to be lowered to various depths with the lid in open position. The hinge is then remotely triggered to close the lid at the desired depth whereupon the container is removed from the liquid body. A self-seating ridged planar seal is employed between the lid and the container. The removed container can be stood upright, and a plurality of vertical internal supporting webs are dimensioned so as to accommodate a pH test instrument in the container. The hinge includes a crank arm having a support post against which a closing or opening tensile force is applied. The crank arm is pivoted from a first position wherein the tensile force creates an opening moment to a position wherein the post lies on the opposite side of a pivot so that a tensile force at the same post creates a closing moment.

Abstract: There is disclosed an apparatus including a calculating circuit for automatic determination of the boron concentration with the Li-ion concentration of the primary cooling water in a pressurized water atomic power plant. The conductivity of a sample of the cooling water is measured before and after the sample water is mixed with a mannitol solution; the Li-ion concentration is calculated from the measurement obtained and the correct boron concentration is calculated with correction based on the Li-ion concentration.

Abstract: A circuit for measuring the PH of fluids includes a coaxial symmetrical probe having a PH probe surrounded by a reference probe; the conductor on which the PH signal passes from the probe to the control panel is within a shield to which is applied the PH voltage; and the differential amplifiers which receive and process the PH and reference signals are mounted on a conductive surface to which is applied the PH voltage.

Abstract: An improved probe assembly for monitoring liquids is provided which includes an electrode housing having an internal receiving chamber, sealing packing means disposed in the chamber and a generally cylindrical electrode enclosed within a flexible, tube-like insulation sheath, which electrode and sheath extend through the receiving chamber and the sealing packing means. The electrode has at least one circumferentially-extending, radially-offset surface disposed opposite the sealing packing means defining an edge against which the sheath is compressed by the packing means so as to effect sealing engagement between the electrode and the sheath.