Abstract: Method and apparatus are disclosed for measuring and controlling the concentration of oxygen in a gas. A sensor (10) is provided having a zirconium dioxide wall (12). One side of the wall is exposed to a reference gas having a known oxygen concentration while the other side is exposed to a gas having the unknown oxygen concentration. An electrical potential is developed at the sensor output, where the magnitude of the potential is dependent upon the relative oxygen concentrations on either side of the sensor wall and the temperature of the wall. The reference gas is selected such that variations in the electrical potential due to temperature changes are minimized over the expected range of temperatures to which the sensor will be subjected during the oxygen concentration measurements and over the range of oxygen concentrations which must be measured.The sensor temperature is measured by measuring the resistance of the sensor, which varies directly with temperature.

Abstract: A sensing device for sensing the position of a continuously moving strip of metal and providing a signal for centering the strip on a given line of movement which has good linearity, good stability, and a time stable output. Segments of a pair of capacitor plates overlap each edge of the strip. These are energized by a square wave signal and the variation in capacity between the plates and the strip caused by lateral movement of the strip is detected by a diode bridge and the resultant signal made available to power apparatus for correcting the position of the web.

Abstract: When a burner is supplied with preheated air, the temperature and density of the preheated air may vary during operation of the burner. When the density of the air supplied to a burner varies, it is necessary to vary the rate at which fuel is supplied to the burner in order to maintain a predetermined air-fuel ratio. To effect a variation in fuel flow with burner air density, the present invention utilizes a secondary air flow to simulate the heated flow of air to the burner. The flow rate of the secondary air varies in a manner which is a direct function of variations in the rate of flow of the heated burner air. Changes in the rate of flow of the secondary air are sensed at a predetermined reference temperature. The sensed variations in the secondary air flow are utilized to effect a corresponding change in the rate of fuel flow to maintain a constant air-fuel ratio.

Abstract: A multi-fuel boiler is provided in which coal is burned in combination with oil or gas in such manner that the particulate emission from the coal, normally relatively high, is reduced to a level comparable to oil. In one example, coal of a quality that would normally burn with a Bacharach smoke spot test number of 6 can be burned with a test number below 2.This is accomplished by utilization of a horizontal oil or gas flame directed across the flue gas exit of the combustion chamber in opposition to the flow of coil combustion gases to change the normal flow pattern of the combustion gases. This creates turbulence, which provides additional combustion time at combustion temperatures in the presence of excess air.

Abstract: Structure for and a method of determining which of a plurality of switches in a series circuit first opens after the circuit has initially been completed, for determining line voltage failure to the series circuit, and for monitoring open switches in the series circuit on start-up, comprising means for and the steps of sensing line voltage failure and the condition of each of the switches and providing sensed signals in accordance therewith, converting the sensed signals into coded output signals representative of the desired information relative to switch and line voltage conditions, and subsequently decoding the coded signals and driving a digital display device therewith to provide a visual readout of line voltage and switch condition. Provision is made for manually decoding the coded signals and providing a display in accordance therewith whereby the first fault in the series circuit prior to the circuit having been completed may be determined.