Abstract: A system for monitoring ambient carbon monoxide. Light from a source (14) is directed against a measuring element (10) which darkens in color as it absorbs carbon monoxide. The light reflected from the element is received by a photocell (16) which generates an electrical signal proportional to the intensity of the reflected light received thereby. The signal is sampled periodically, and stored in a microprocessor (24) which computes the rate of change of the signals. The periodic measurement of the intensity of the light can be varied in response to the rate of change of the light intensity measurement. When the rate of change reaches a level indicative of an unsafe level of ambient carbon monoxide, an alarm (34) is energized. Light from the source is simultaneously directed against a reference element (12) with the light reflected therefrom being received by a photocell (18) which generates an electrical signal proportional to the intensity of the light received thereby.

Abstract: A method and apparatus for on-line analysis of a coal sample. Four radial arms (16) extend from the output shaft (28) of an indexing motor (14). Sample cups (12) at the ends of the arms are indexed along a circular path past a filling station (18) where the cup is filled with pulverized coal, an analyzing station (20) where various chemical analyses are performed on the coal sample, a dumping station station (22) where the residue of the coal sample is dumped for disposal, and a cleaning station (24) where the sample cup is cleaned in preparation for another analysis cycle.

Abstract: An arrangement for isolating an optical surface from a contaminating environment utilizes concentric inner and outer tubes defining an annular purging space therebetween. The inner and outer tubes are both open ended with the open ends facing the contaminating environment. The optical surface is positioned in the inner tube and is spaced from the open end of the inner tube. The inner tube is made of porous material and the space is supplied with a purging gas so that at least some of the purging gas filters into an inner space of the inner tube to prevent an aspiration of contaminants into the inner tube from the open end thereof. A preferred porosity range of 1 to 40 microns is selected for the inner tube which preferably has a length to diameter ratio of from about 5 to 1.

Abstract: A method for on-line analysis of a coal sample. Four radial arms (16) extend from the output shaft (28) of an indexing motor (14). Sample cups (12) at the ends of the arms are indexed along a circular path past a filling station (18) where the cup is filled with pulverized coal, an analyzing station (20) where various chemical analyses are performed on the coal sample, a dumping station station (22) where the residue of the coal sample is dumped for disposal, and a cleaning station (24) where the sample cup is cleaned in preparation for another analysis cycle.

Abstract: A temperature actuated air flow control comprises a fluid inlet for the gas sample which is connected to an exhaust line through an intermediate venturi chamber into which a gas such as air is vented in order to aspirate the flow of the gas through the inlet to the exhaust. The amount of flow of the aspirating gas controls the quantity of flow of the sample gas through the inlet to the exhaust. A valve chamber in the aspirating gas passage comprises a bimetallic plate which is flexed between a position in which it closes a flow passage for the aspirating gas to one in which it opens the passage. The bimetallic plate is flexed by temperature change. The device advantageously functions to provide for the inflow of a sample or test quantity of a gas and flows through a chamber having a gas sensor to determine the characteristics of the gas and is directed through a venturi section and out through an exhaust.

Abstract: A calorimeter and method of obtaining the calorific value of a test gas comprises a pair of constant flow pumps one for supplying air at known volumetric flow and the other for supplying a test gas at known volumetric flow. The known volumetric flow of air is maintained at a level sufficient to provide enough oxygen to fully burn all oxidizable components of the test gas. The air and test gas are mixed and catalytically burned in a heated block and the combustion products are thereafter supplied to an electrochemical oxygen measuring cell which measures the remaining oxygen in the mixture. A circuit arrangement is utilized to obtain a value proportional to the difference between the remaining oxygen and original amount of oxygen which value is proportional to the amount of oxygen utilized and in turn proportional to calorific value of the test gas.

Abstract: An opacity monitor (10) including a light source (12) mounted on one side of a duct (14), and a detector (16) mounted on the opposite side of the duct is disclosed. The light source (12) and the detector (16) are rotated by motor means (26, 36), respectively, between a first position aligned with each other along an open light path defined across the duct (14) and a second position aligned with each other on opposite sides of a calibration tube (18) extending across the duct (14). Shutters (28, 38) rotate with the light source (12) and the detector (16), respectively, and are aligned with the calibration tube (18) when the light source (12) and the detector (16) are aligned with the open light path, and vice versa.

Abstract: A differential thermocouple hydrogen gas detector (10) is provided by coating one thermocouple junction (34) of a differential thermocouple pair (34, 36) with a Palladium-Silver alloy catalyst (46) and the other thermocouple junction (36) with a non-catalyst (52). Heated hydrogen gas reacts with the catalyst (46) to liberate heat to the catalyst coated thermocouple junction (34) in proportion to the concentration of hydrogen gas and proportionally raise the temperature of the catalyst coated junction (34) above that of the non-catalyst coated junction (36). The output signal (44) from the differential thermocouple device (34, 36) thus provides an output signal indicative of the concentration of hydrogen gas.

Abstract: A differential thermocouple hydrogen gas detector (10) is provided by coating one thermocouple junction (34) of a differential thermocouple pair (34, 36) with a Palladium-Silver alloy catalyst (46) and the other thermocouple junction (36) with a non-catalyst (52). Heated hydrogen gas reacts with the catalyst (46) to liberate heat to the catalyst coated thermocouple junction (34) in proportion to the concentration of hydrogen gas and proportionally raise the temperature of the catalyst coated junction (34) above that of the non-catalyst coated junction (36). The output signal (44) from the differential thermocouple device (34, 36) thus provides an output signal indicative of the concentration of hydrogen gas.

Abstract: A gas sampling system is provided having a combustibles detector and an oxygen detector supplied from a common sample line by their own individual aspirators. The aspirators are sized to allow the one aspirator to overpower the second aspirator whenever the common sample inlet is blocked a predetermined amount to thereby cause oxygen rich supply air to flow through the oxygen detector causing the oxygen detector to register an abnormal condition as an indication of blocked sample inlet.

Abstract: A fluid sampling system has a series of sample probes having inlets located at different positions across a fluid conveying duct. The outlets of all the sample probes are connected to a valve assembly. Each of the sample probes is made to have substantially the same length and diameter to provide equivalent transport times and volumes to fluids sampled from the various locations. The valve assembly allows selective connection of the sample probes to the fluid analyzer allowing either individual sample probes to be connected to the analyzer to determine local duct conditions or the connection of all the sample probes to the analyzer to determine the average duct condition.

Abstract: A colorimetric analyzer automatically and continuously measures the transmission of light through a sample which has been mixed with reagents. Precise volumes of the sample are repeatedly measured by a siphon tube. Volumes of the reagent are added to the sample at different times in a measuring cycle. The reagent is added at different places in the analyzer so that it is possible for two different time-consuming reactions to proceed simultaneously. The mixed reagent and sample is supplied to a measuring cell which includes a source of light and a photocell. The distance between the source of light and the photocell are adjustable to accommodate analyses of mixtures with widely varying light transmission while providing a full scale output indication. The output of a photocell is applied to a sample and hold circuit during time intervals when the reactions of the reagents with the sample have been completed.