Abstract: A zero air generating system comprises a hydrocarbon and NO oxidizer and a molecular sieve unit which are interconnected by suitable lines for continuous processing of the air stream. Flow control means is provided to maintain the flow rate of the air being treated to 5 liters/minute or less. The system may also include a separate NO to NO.sub.2 converter. The system purifies shop air by reducing the concentration of contaminants such as NO.sub.2, CO, CO.sub.2, H.sub.2 O and other remaining unoxidized hydrocarbons to levels acceptable under the IM-240 specification for instrument air. In a preferred embodiment of the invention, two parallel connected molecular sieves units are utilized in the system. Thus the air being treated can alternately flow through one molecular sieve while the other unit is in the process of being regenerated.

Abstract: A method and apparatus for the chemiluminescent determination of NO/NO.sub.x in a sample gas is disclosed in which the NO.sub.x portion of the gas stream is catalytically converted in a preconditioned vitreous carbon bed at a relatively low temperature effective to catalytically convert NO.sub.x to NO and below 200.degree. C. The vitreous carbon is preconditioned by heating at a temperature of between 300.degree. C. and about 500.degree. C. for a sufficient period of time, on the order of two to five hours. The apparatus consists of a converter containing the preconditioned vitreous carbon in communication with a reaction cell consisting of a hollow cylindrical housing having an open end closed by an optical filter. A suitable photodetecter is disposed to detect light emitted through the optical filter. A chemiluminescent reaction between ozone and NO in the sample stream occurs in a reaction chamber defined by the interior of the housing. A reflector element may be disposed in the reaction chamber.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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%.

Abstract: An electrochemical reference electrode for use in ion potential measurements of solutions. The liquid junction structure of the electrode comprises a hydrophobic polymer having a suitable salt distributed therethrough and held in place to prevent leaching by a filamentary structure of the polymer. The liquid junction structure is a diffusion membrane material and permits ionic communication between the salt bridge solution of the electrode and the sample solution essentially by means of diffusion, rather than by liquid flow. The entire electrode body may be made of the polymeric material. The electrode is particularly suited for process applications.

Abstract: A method of analyzing nitric oxide (NO) in a gas stream containing nitrogen dioxide (NO.sub.2) and a scrubber apparatus for selectively removing nitrogen dioxide from a gas stream containing nitric oxide. The scrubber apparatus comprises a container having an inlet port for the gas stream and an outlet port. The scrubber material in the container includes silver carbonate whereby the scrubber has an efficiency of at least about 99% and a capacity of about 11.5 parts per million hours of 99% nitrogen dioxide removal per gram of silver carbonate. The method involves passing the gas stream through a scrubber material containing silver carbonate so as to remove nitrogen dioxide from the gas stream while passing the nitric oxide unattenuated and thereafter conveying the gas stream from the scrubber material to an analyzer for nitric oxide. The gas stream is analyzed with the analyzer to determine the nitric oxide concentration therein.