Abstract: A linearizing circuit (10) is disclosed for devices having logarithmic outputs, such as electrolytic oxygen detectors (12). The circuit (10) has an inverting biasing circuit (14) and a scaling circuit (16) connected to an antilog function generator (18) and is calibrated by zeroing the inverting biasing circuit (14) at an extreme point of the desired range and sealing a second point on the desired range in the scaling circuit (16).

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 method of manufacturing a differential thermocouple combustibles sensor is disclosed which makes the sensor relatively insensitive to sulfur poisoning. To accomplish this the catalytic thermocouple junction of a catalytic-non-catalytic junction pair is formed by coating it with a gel to increase the surface area and then with a chloroplatinic acid solution to make it catalytic. The catalytic junction is then treated with H.sub.2 S to achieve a high catalyst surface area.