Beckman Instruments, Inc.

Beckman Industrial Corporation

Rosemount Inc.

Radhakrishna M Neti

John N Harman, Iii

Kenneth B Sawa

Ray Lawrence Roggenkamp

Fred Charles Sittler

Adrian C Toy

Carl N Cederstrand

John P Frain

Laurence Drell Graham

Raymond E Rocks

David H Freund

Colin C Bing

A solid state, thin film moisture sensing element is disclosed. The sensing element is fabricated by thin film deposition of at least a pair of two layer electrodes on an insulating surface. The active surface of the element is then coated with a layer of hygroscopic material and placed in a diffusion limiting housing to complete the sensing element assembly.

Thin film moisture sensing element

An improved sensor for dissolved oxygen measurement comprising a body having an electrolyte reservoir and electrolyte contained therein and an opening for communication between the exterior of the body and the reservoir and an anode and cathode concentrically disposed in the body adjacent the opening. A thin polymeric membrane permeable to oxygen and impermeable to the electrolyte seals the opening. The working surfaces of the anode and cathode, that is the surfaces adjacent the membrane, are spaced apart from the membrane to define an electrolyte space between the working surfaces and the membrane. A noble metal screen is disposed on the working surface of the anode. Preferably the screen completely covers the anode working surface and a portion of the screen which would normally overlie the working surface of the cathode is cut away so that the cathode working surface is unobstructed. The noble metal screen over the anode surface results in a substantial retention of electrode stability over a period of time as compared to sensors similarly constructed but which do not include the noble metal screen over the anode working surface.

Electrochemical sensor

A solid state sensing element comprising a nonporous, structurally stable, electrically insulating substrate on which is disposed spaced apart pairs of electrodes for contact with moisture. A hygroscopic electrolytic material is located in close proximity to the electrodes as by coating the electrodes with the hygroscopic material. A catalyst is deposited in close proximity to the electrodes and is electrically insulated therefom. The electrodes are connected to a source of potential and current measuring instrumentation. Moisture is trapped by the hygroscopic material and electrolyzed at the electrodes. The catalyst recombines the hydrogen and oxygen thus formed to water so there is no net consumption of water by the element and equilibrium is established at the sensor surface and the atmosphere adjacent the sensor surface. Any change in partial pressure in the atmosphere adjacent the sensor surface is reflected by the movement of water molecules to the area of least concentration which produces a change in amount of moisture being electrolyzed and an increase or decrease in the current required by the element to electrolyze water.

Solid state sensor element

An improved electrochemical cell is described which comprises at least one electrode having increased signal strength achieved by treating at least the working surface of the electrode with a coating of a polytetrafluoroethylene and a catalyst metal selected from the group consisting of platinum and the oxides thereof in an aqueous oligosaccharide solution. Following coating, the electrode is heated to a temperature below the sintering temperature of the polymer to thermally convert the oligosaccharide in the presence of the catalyst metal and drive off the conversion products. An electrode thus treated exhibits a substantially inproved signal strength as compared to an electrode of the same construction which has not been treated in accordance with the invention.

Method for treating electrodes and improved electrochemical cell

An improved solid state electrode system for measuring the pH of fluids at temperatures as high or even higher than that corresponding to the critical point of water (374.2.degree. C.). A stabilized metal oxide based ceramic member having a predetermined thickness is coupled to a first metallic conductor by a uniform, solid oxygen-free electrolyte to serve as a pH sensing electrode. A body of an electrochemically inert material, which preferably comprises a stabilized metal oxide based ceramic member having a lesser thickness or a greater porosity, is coupled to a second metallic conductor by a similar uniform solid electrolyte to serve as a reference electrode. Together the pH and reference electrodes form an electrode system that is suitable for use in applications in which the temperatures and/or pressures of the test solution preclude the use of conventional electrodes. A variety of configurations and compositions are disclosed which allow the electrode system to be fabricated in an improved manner.

Solid state electrode system for measuring pH

A pH electrode which is capable of withstanding repeated exposures to sterilizing temperatures. An electrode body having a pH sensing member is at least partially filled with a bed of electrochemically inert particles. After an internal reference is inserted into the particle bed, the bed is injected with a quantity of electrolyte which is sufficient to establish continuity between the sensing member and the internal reference, but which is not sufficient to produce destructive internal pressures when the electrode is subjected to sterilizing temperatures. The electrode is completed by forming a seal between the electrode body and the internal reference.

Sterilizable pH electrode and method for producing the same

A membrane type amperometric gas sensor is provided with a pressure equalization passage between the exterior and interior of the cell in which the electrodes are located. Cell fluids move into and out of the passage as necessary to maintain the pressure inside the cell substantially equal to the pressure outside the cell over a wide range of pressures and temperatures. A movable fluid plug or seal located in the passage protects the fluids inside of the cell from contact with the gas being sensed and from the atmosphere for all permissible values of pressure and temperature.

Pressure equalization system for membrane type amperometric sensors

A fluorescent sulfur dioxide analyzer that includes a generator for producing a standard gas of known sulfur dioxide content. A source of ultraviolet radiation illuminates the interior of a reaction chamber in which an oxygen containing gas is passed over a deposit of sulfur. During passage, a part of the oxygen reacts with the sulfur to produce sulfur dioxide. Because the quantity of sulfur dioxide is predictable and reproducible, the resulting sulfur dioxide containing gas is suitable for use as a standard or span gas in the analyzer with which it is used, thereby eliminating the need for the storage tanks or permeation tubes.

Fluorescent sulfur dioxide analyzer having an improved sulfur dioxide

A solid state ion-sensitive measuring electrode is disclosed in which a filler solution comprising sodium silicate is provided between an outer glass membrane of the electrode and an internal metallic wire which serves as a conductor from the electrode to a meter. The filler solution is inserted into the electrode as a liquid, and is subsequently dehydrated to provide a permanent solid-state matrix which is electrically conducting between the outer glass membrane and the internal wire.

Solid state ion-sensitive electrode and method of making said electrode

A carbon monoxide detection apparatus and process are disclosed in which the amount of carbon monoxide is measured by oxidizing it and measuring the heat of oxidation. To accomplish this platinum oxide is used as the catalyst and an operating temperature is maintained at which oxidation of carbon monoxide occurs in the presence of platinum oxide. Various types of heat-change-responsive techniques are disclosed, including measurement of the voltage drop across forward-biased solid-state diodes, and measurement of the voltage generated by thermo-couples.

Carbon monoxide detection apparatus

In a sulfur dioxide fluorescence analyzer, a method and apparatus for eliminating the fluorescence effects of nitric oxide is disclosed wherein a sample gas is mixed with a diluent which substantially quenches nitric oxide fluorescence.

Nitric oxide interference free sulfur dioxide fluorescence analyzer

An electrochemical sensor for determining the O.sub.2 content of a fluid characterized in that the electrolyte employed therein is selected from a group consisting of amino alcohols having 2 to 12 carbon atoms, morpholine, and mixtures thereof. Optimally, the electrolyte can further comprise a supporting electrolyte selected from a group consisting of inorganic halides, organic supporting electrolytes, and mixtures thereof.

High temperature, CO.sub.2 interference free, electrochemical O.sub.2

An improved catalytic reactor system and method for removing interferents such as reactive hydrocarbons from the gas being sampled by gas component determination apparatus is disclosed. The sample from which the interferents are to be removed is blended with ozonized air and saturated to at least 15% with water vapor. The mixture is then passed through the catalytic reactor which, preferably, contains a mixture of platinum oxide mixed with sand and maintained at an operating temperature of 200.degree. to 280.degree. C. Additional catalytic mixtures which may be employed in the reactor are also disclosed. Methods of preventing the poisoning of catalytic reactors and rejuvenating poisoned catalytic reactors are also disclosed.

Catalytic reactor systems method and apparatus

A method of measuring trace level hydrogen chloride concentration in a gas stream is disclosed. The gas stream containing hydrogen chloride is passed through a heated vitreous carbon catalyst and then mixed with ozone in a point source reaction chamber. The light emitted in the chemical reaction is measured by a sensitive amplifier and the output is displayed on a meter, recorder, or any other suitable device. Apparatus for measuring trace level hydrogen chloride concentration in a gas stream is also disclosed.

Method and apparatus for the chemiluminescent detection of HCl

An improved electrode for use in oxygen determination is disclosed. Interference from carbon dioxide is eliminated by combining an improved electrolyte with means for permitting rapid electrolyte movement into and out of the space between the cathode and the membrane covering the cathode to maintain the pH of the electrolyte in the space substantially constant. The electrolyte consists of a KCl solution containing KOH of from 0.1 to 2%.

Growing community of inventors

Brea, CA, United States of America

Radhakrishna M Neti