Abstract: This invention is a process for detecting low levels of nitrogen oxides (NO.sub.x) in a flowing gas stream (typically an exhaust gas stream) and a catalytic NO.sub.x sensor which may be used in that process.

Abstract: A sensitive and stable microcalorimeter comprises a cell (1) for a sample of material to be studied and for retaining the sample. The cell walls (2) are of an inert material such as PTFE, and temperature sensors (7) are located within the cell walls at specified positions.

Abstract: A method of determining the critical vapor pressure of a hygroscopic material, such as a drug. A drug sample is placed in a substantially isothermal environment. A vapor, such as water vapor, at a given pressure is then placed in the ambient air over the drug. The rate of heat production from this sample at the given water vapor pressure, or the humidity of the air above the sample, is then measured. The water vapor pressure over the drug is gradually increased. Simultaneously, the rate of increase in heat production from the drug sample, or the rate of change of the relative humidity of the air above the drug sample, is measured. A marked increase in the rate of heat production generated by the drug, or a marked change in the relative humidity of the air over the sample, signals the attainment of the critical water vapor pressure.

Abstract: A temperature gradient calorimeter and method of calculating heats of reactions is disclosed. The calorimeter has a two dimensional array of reaction chambers located in a thermally conductive substrate. A first heat transfer medium is in thermal contact with the thermal conductive substrate and is located at one region of the array of reaction chambers. A second heat transfer medium is in thermal contact with the thermal conductive substrate and is located on the opposite side of the array from the first heat transfer medium. The first and second heat transfer mediums are at two different temperatures. That temperature difference produces a temperature gradient across the array of reaction chambers.The fluorescence intensities are measured for reactant samples located in the array of reaction chambers.

Abstract: A highly sensitive, quick recovery differential microcalorimeter includes two matchingly formed and cooperatingly disposed flow channels. Each flow channel has two inlets, at least one mixing assembly connected to each fluid inlet, a fluid outlet connected to each mixing assembly, at least one heater element surrounding at least a portion of each fluid outlet, and a plurality of sensors surrounding at least a portion of each fluid outlet. Each of the mixing assemblies includes a mixing chamber and at least one entry manifold connected to a fluid inlet and having a plurality of ports which connect to the mixing chamber.

Abstract: An apparatus for correcting an initial measurement of the concentration of a first water soluble species dissolved in a water-based component of a biological fluid that also includes a second water soluble species and a volume occupying component, the initial measurement having been taken using an original sample of the fluid that had been diluted by an amount of additional aqueous solution to form a diluted sample is disclosed; the concentration of the second water soluble species is measured in an undiluted sample of the biological fluid to obtain a direct concentration and is measured using a diluted sample of the fluid to obtain an indirect concentration, and the initial measurement of concentration of the first species is adjusted based on a combination of the direct and indirect concentration determination of the second species.

Abstract: A circuit for measuring temperature differentials in a calorimeter is disclosed. The temperature differential between the reference element and sample element containing a radioactive material is measured via a wheatstone bridge arrangement of thermistors. The bridge is driven with an alternating current on a pulsed basis to maintain the thermal floor of the calorimeter at a low reference value. A lock-in amplifier connected to the bridge phase locks a signal from the bridge to the input pulsed AC signal to provide a DC voltage. The DC voltage is sampled over time and provided to a digital computer. The digital computer, using curve fitting algorithms, will derive a function for the sample data. From the function, an equilibrium value for the temperature may be calculated.

Abstract: A calorimeter for measuring the thermodynamic and kinetic characteristics of chemical reactions, microbial fermentations, and other processes of industrial importance is described. The present invention also relates to a method of operation of this apparatus.

Abstract: A disposable mixing cell and method for evaluating the thermal hazard due to mixing substances includes a first container adapted for the accommodation of a sample of one substance and a second container in the form of a syringe adapted to accommodate a sample of a second substance. The syringe is operable to discharge the second substance into the substance in the first container and includes a paddle by means of which the two substances may be mixed. The syringe is sealed within the first container, except for the outer end of its operating plunger which is accessible externally of the first container. The mixing cell is placed in a batch type fluid calorimeter which is capable of indicating the thermal reaction resulting from the mixing of the two substances. A gas conduit may be provided to conduct gas evolved from the mixing of the two substances outward of the cell.

Abstract: Colorimetric apparatus which includes a water tank, a container in the tank, a pressure vessel in the container, and a pump. The apparatus is worked in three phases. In the first phase the water in the tank is mixed and brought to a desired temperature. In the second phase water is pumped from the tank, through a jacket which surrounds the pressure vessel, and back to the tank, to bring the pressure vessel to the tank temperature. After a sample of material is combusted in an oxygen atmosphere in the pressure vessel, the third phase takes place. Water is circulated in a closed path which includes the jacket and the temperature of this water is monitored. The variation of this temperature is used to calculate the colorific value of the substance.

Abstract: A calorimeter for measuring the thermodynamic and kinetic characteristics of chemical reactions, microbial fermentations, and other processes of industrial importance is described. The present invention also relates to a method of operation of this apparatus.

Abstract: The device has a transparent capillary assay tube attached at its upper end to a lateral portion of the support structure of the device. The lower free end of the assay tube is engageable with an absorbent material upon manual downward deflection of the support structure. The assay tube is filled through a funnel shaped aperture in the lateral portion of the device, and the tube is drained by engaging the lower free end of the tube with the absorbent material. By attaching appropriate antibody, antigen or hapten to the inner surface of the tube, immunoassays may be performed in the tube.

Abstract: The measuring probe is equipped with a pellistor and renders possible directly determining in a trouble-free manner volatile constituents which are contained in a liquid medium to be investigated and which can be chemically converted with an accompanying heat effect. Heating devices are provided and, due to the prevention of condensate formation, greatly contribute to obtaining high measuring precision. The response time of the measuring probe can also be significantly reduced by heating a membrane which separates a measuring space containing the pellistor from the liquid medium to be investigated. The measuring probe can be used with advantage for monitoring microbiological processes, for example, in a fermenter.

Abstract: A precision calorimeter which comprises a heater, an agitator and a detection bath which are disposed in a temperature controlled bath and in which gaps formed between them are filled with a liquid; and a detection unit placed in the detection bath, a gap formed therebetween being filled with a liquid; the detection unit being comprised of a detection element, a pipe for passing a sample therethrough provided with a mixer and a reference heater which are arranged between metallic pieces.

Abstract: To regulate and monitor material concentrations, e.g., sodium chlorite or hydrogen peroxide, measuring cells are employed in which these substances are reacted to completion with another substance, e.g., sulfur dioxide, in an exothermal reaction. The resulting temperature rise is then a measure for the concentration. A simple measuring cell includes a pipe section provided at both ends with mounting devices for mounting in the delivery line conveying the reaction medium. There is mounted in this pipe section a U-shaped pipe section which is open at both ends and has a smaller diameter, and whose two arms extend into the pipe section with a larger diameter. The center section of, and parallel to, is located outside of the larger pipe and is provided with a thermal insulation, a supply line for the reacting substance, and a temperature sensor.

Abstract: To regulate and monitor material concentrations, e.g., sodium chlorite or hydrogen peroxide, measuring cells are used in which these substances react to completion with another substance, e.g, sulfur dioxide, in an exothermal reaction. The resulting temperature rise is then a measure of the concentration. A measuring cell comprises a pipe section provided at both ends with mounting devices for installation in the delivery line transporting the reaction medium. Within this pipe section there is positioned axially a smaller diameter pipe section which is open at both ends, into one open end of which projects the supply line for the reacting substance and at the other end of which a temperature sensor is installed.

Abstract: Micro-scale chemical process simulation apparatus is disclosed which is useful for design of full-scale processes and associated equipment as well as emergency relief systems. A thin-walled vessel for receiving a quantity of the material to be evaluated is supportd within and thermally insulated from the walls of a surrounding containment unit. A guard heater is provided around the vessel and temperature thermocouples and pressure transducers are strategically located to monitor the temperature conditions existing in the material in the vessel as well as the pressure within the vessel and the containment unit respectively. Fluid may be selectively introduced into or exhausted from the containment unit to maintain a required pressure balance between the interior of the vessel and that of the containment unit.

Abstract: Apparatus for measuring the calorific value and other quantities of combustible substances. The apparatus includes a support structure to which a pressure vessel is mounted. The pressure vessel has a cap which provides access to a combustion chamber within the pressure vessel. The pressure vessel is preferably of a double walled construction and a fluid flowpath is formed between the two walls. During combustion tests the temperature of fluid in the flowpath is monitored. Surrounding the pressure vessel is a temperature loss control means which in the preferred embodiment comprises a water jacket through which water is circulated at constant temperature. The invention extends to a method of measuring thermal quantities of combustible substances as well as to a method of determining the sulphur content of combustible substances.

Abstract: A catalytic calorimeter measures the heat value of a gas and includes a chamber for receiving gas and air. A catalyst within the chamber causes the combustion of the gas and air, while a first thermocouple provides a signal indicating the temperature of the gas and air prior to combustion. A second thermocouple indicates the temperature of the catalyst, which is heated by an electrical resistance heater. A first temperature controller is connected to the second thermocouple and the heater for maintaining the catalyst at a predetermined temperature. A heat sink within the chamber absorbs heat from the products of the combustion of the gas and a third thermocouple indicates the temperature of the heat sink. A Peltier effect thermoelectric cooler is provided to remove heat from the heat sink. A second temperature controller connected to the third thermocouple and the cooler maintains the heat sink at a predetermined temperature.

Abstract: An apparatus for determining the heating value of a fuel gas stream of variable composition utilizes a housing of high thermal conductivity defining a small volume combustion chamber, and filled with a bed of highly thermally conductive particles surrounding an electrical-resistance heater. The heater maintains the internal temperature of the chamber above the combustion point of the fuel gas, to totally combust the enclosed sample. The bed of particles transmits the heating effects of the combustion to the housing. A temperature sensor attached to the housing communicates with a feedback controller which acts to maintain the housing temperature constant, by appropriately adjusting the electrical energy supplied to the heater. Means are provided to correlate changes in the electrical energy to the heating content of the fuel sample.

Abstract: Method and apparatus system for quickly determining on site if chemicals which are to be mixed can be done so safely without having a run-away exothermal reaction take place and without exposing personnel to the chemicals. The invention is particularly useful in dumping quantities of waste chemicals into a waste chemical reservoir containing a very complex mixture of many other waste chemicals.

Abstract: An apparatus and method for indicating the temperature of the environment into which a reaction vessel may be placed is provided by a container holding a thermally efficient fluid. The container has an identical external configuration substantially identical to the reaction vessel and is adapted to be positioned within the environment in place of the reaction vessel. A temperature sensor in thermal communication with the thermally efficient fluid provides an electrical parameter indicating the temperature of such fluid and thus the environment of the reaction vessel.

Abstract: A method of determining heat losses due to incomplete fuel combustion consists in that periodic sampling of fuel combustion products is carried out. The sample is separated into two parts, one of which includes a gaseous phase, and the other, a solid and a gaseous phases. Oxygen concentration in each part is assessed, after which both parts are heated and burnt up to determine oxygen concentration after burning. Oxygen losses in the gaseous phase and in the mixture of the solid and the gaseous phases are determined, and heat losses due to chemical and total underburning of fuel are defined as the ratio between oxygen losses. Then heat losses due to mechanical underburning of fuel are estimated as the difference of heat losses due to total chemical and mechanical underburning, and chemical underburning of fuel.

Abstract: A general-purpose apparatus for thermochemical quantitative analysis, operable upon the principle of measuring temperature variations accompanying chemical reactions between a solid and a liquid substance as well as between two solutions. An exchangeable reaction vessel made of formed polystro in Dewar vessel is received in a heat-insulated receptacle with a thermostat controlled bath, the reaction vessel being provided with a cover having an opening for a removable lid which supports a temperature sensor and a stirring rod. The removable lid has openings to receive a dose feeder for a solid specimen and/or a dose feeder for reagent solutions.

Abstract: A calorimetric apparatus for determining the calorific content of a fuel gas uses a reactor for producing oxidation of the fuel gas and a combustion gas in the presence of a catalytic oxidizer. The catalytic oxidizer is mounted on one end of a thermo-electric element which element has a heat absorbing end and a heat emitting end when energized by an electric current to produce a Peltier effect. The catalytic end of the element is mounted within the reactor while the other end is located outside of the reactor. The temperatures of the ends of the element are detected by a controller and the difference therebetween is maintained at a predetermined level during the catalytic reaction by the controller developing a control signal to control the supply of the electric current to the element. A display control signal is derived from the control signal by the controller and used to control a display for indicating the calorific content of the fuel gas.

Abstract: A calorimetric apparatus for determining the calorific content of a fuel gas uses a reactor for producing oxidation of the fuel gas and a combustion gas in the presence of a catalytic oxidizer. The oxidizer is heated by a constant current supply to a catalytic oxidation temperature. The resistance of the catalytic device is measured before and during the oxidation reaction which produces an additional heating of the catalytic device. The change in resistance is used to control a valve arranged to determine the flow rate of the fuel gas to the reactor. A display control signal is derived from a valve control signal and used to control a display for indicating the calorific content of the fuel gas.

Abstract: The accelerating rate calorimeter disclosed herein is an instrument designed for accurately determining the adiabatic thermal runaway characteristics of reactive chemicals. The mode of operation involves measuring the adiabatic self-heat rate of exothermic chemical reactions to determine the acceleration of the reaction rate as a function of temperature. The basic instrument includes a sample vessel which is positioned inside a reaction chamber. The environment surrounding the sample vessel is a gas, such as air, or an inert gas, or it can be a vacuum environment. Separate heater means are provided for heating the reaction chamber and the sample vessel.During the exothermic reaction of the chemical in the sample vessel, the temperature of the reaction chamber and the sample vessel are continuously monitored by separate temperature sensing means.

Abstract: An apparatus for measuring an exothermic reaction in a thin film of a photopolymerizable, ethylenically-unsaturated mass, which apparatus comprises a thin foil differential thermocouple means, a pore means adjacent to and mounted above the thermocouple means, a perforated plate means positioned above the pore means and an ultraviolet light source means positioned above the plate means is disclosed.

Abstract: The ozone content of ozone-containing gas mixtures is determined in a process wherein the ozone is converted to oxygen and which includes channeling a gas mixture containing nitrogen oxides and possibly water vapor through an adsorbent of aluminosilicate which contains 2 to 20% by weight of aluminum oxide and the aluminosilicate is of spherical shape with a particle diameter of 2 to 5 mm and a specific area of 200 to 650 m.sup.2 /g and an average pore diameter of 5 to 10 nm.

Abstract: A nonadiabatic calorimetric technique useful broadly for quantifying the reaction kinetics of thermally unstable solids is based on the distinguishing mode of establishing, under near steady state conditions, a thermal gradient across a reaction sample contained between monitored hot and cold surfaces, stepwise or rampwise increasing the temperature of the hot surface, and quantifying the maximum temperature that is withstood by the sample at the inception condition of a thermal runaway reaction. The critical hot surface temperature recorded by the experiment is a function of the cold surface condition, i.e., the applied thermal gradient. At least two critical hot surface temperatures, which are required for calculations, are generated by repeating the experiment under differing cold surface conditions. Solution of the steady-state differential equation describing the system, utilizing the experimental data, yields the general kinetics of the decomposition reaction of the tested solid.

Abstract: The concentration of organoaluminum compounds in their solutions can be determined quantitatively, even in a range of less than 10 mmols/dm.sup.3, when adding to the solution to be analyzed instantaneously an excess of reactant and when measuring the produced reaction heat.

Abstract: A heat-insulating enclosure contains temperature-regulating means and open-topped vessels each containing a sample of predetermined volume and transferred from a storage position to an analysis position in which a predetermined volume of reagent solution is contacted with the sample. Means are provided for detecting the respective temperatures of the sample and the reagent, for detecting the heat flux released and limiting thermal variations in the vicinity of each sample.

Abstract: The adiabatic calorimeter apparatus disclosed herein is designed for chemical hazard research, particularly the study of self-heating reactions, which can result in a runaway situation. The reaction vessel and associated components in this apparatus closely simulate the structure and operation of a typical chemical plant reactor. The reaction vessel is fitted into a metal shell and the entire unit is suspended in an insulated oven. During the exothermic reaction the adiabatic temperature rise and pressure rise is simultaneously monitored and recorded as a function of time. A first stage control system maintains the temperature of the reaction vessel in equilibrium with the reaction mix and utilizes electrical energy to compensate out the heat capacity effect of the reactor. A second stage control keeps the temperature of the oven and the reaction vessel at the same level, to insure that the reaction is taking place in an adiabatic environment.

Abstract: A system for determining photo-chemical reaction heat evolved from a sample material irradiated with radiant energy comprises a calorimeter having a pair of sample holders connected to heat-leakage type thermo-electric elements which develop electric output signals proportionate to the amount of heat energy conducted therethrough. Both sample holders are initially irradiated with radiant energy before disposing the sample material thereon to heat the sample holders and thereby develop electric output reference signals. The amount of radiant energy being irradiated on at least one of the sample holders is then selectively adjusted to effectively compensate for any difference between the two reference signals.