Abstract: During the measurement of oxygen content of a gas with a solid electrolyte material capable of oxygen ion conductivity the electrolyte is heated to maintain a constant control temperature. If the ambient temperature changes, an offset or error is introduced into the oxygen measurement. An apparatus and method is provided to automatically compensate for any such offset. Thermocouple means are provided in series with the electrolyte circuit so that a thermal emf if generated due to any differential between ambient and control temperatures. The thermocouples are arranged to generate a net thermal emf which opposes the emf generated by the electrolyte by an amount which automatically compensates for any offset due to the temperature differential. If the ambient and control temperatures are the same, there will be no offset and no net thermal emf.

Abstract: A modification of a basic jack-shaft control apparatus for a combustion system to provide a trim control. A first radial arm is mounted on a first rotating shaft which controls a fuel valve and a second radial arm is mounted on a second rotating shaft which controls an air damper. Ordinarily, a linking rod connects the radially outward ends of said first and second radial arms. The trim modification comprises attaching one end of a third radial arm to the radially outward end of either said first radial arm or said second radial arm. A third rotating shaft is attached to the third radial arm where it is attached to said first or second radial arm. The third radial arm rotates under the influence of trim control motor means on a plane transverse to the plane of rotation of the arm on which it is mounted. The linking rod connects the radially outward end of the third radial arm with the radially outward end of either said first or second radial arm to which the third radial arm is not otherwise attached.

Abstract: A flow inducer apparatus for positioning in a duct containing a flowing stream for continuously and rapidly receiving a sample of gas from and returning said sample to the flowing stream in said duct. Said apparatus comprises inlet opening means extending around an entire outer circumference of said apparatus to receive the sample of said flowing stream regardless of the rotational disposition of said apparatus in the duct. Said apparatus also comprises an integral discharge aspirator means. The discharge aspirator means is open to the surrounding duct along an entire outer circumference of said apparatus for receiving a portion of said flowing stream regardless of the rotational disposition of said apparatus in the duct. The discharge aspirator means is adapted so that the movement of the stream flowing in the duct tends to draw the sample through the apparatus and thereby provide the energy for operation of the flow inducer.

Abstract: Air trim control actuator mechanically connects a fuel flow device to an air flow device for setting the air to fuel ratio in combustion apparatus. An air to fuel ratio control unit is responsive to electrical input signals from an oxygen sensor that monitors the combustion products in the stack emissions. The air trim actuator includes a pivotally mounted input arm that is mechanically connected to the control unit and is pivoted to a preselected position corresponding to the selected boiler load. The input arm is connected by a link to an output arm which is pivoted through a preselected range of movement to control the position of the damper. The output arm has an elongated arcuate slot for receiving the end of the link. The output arm is pivoted to a position corresponding to the pivoted position of the input arm for selectively positioning the damper to provide air flow to the boiler for the desired air/fuel ratio.

Abstract: A gas analyzer is provided which is comprised of two gas sample flow loops joined at an angle to each other, one being an eductive loop that originates and returns to the chamber or conduit from which a gas sample is to be drawn and the other being a convective loop that joins in fluid flow communication with the eductive loop at a point upstream from its eductor device.

Abstract: An eductive flow loop has an inlet leg conduit projecting into an exhaust stack and an outlet leg conduit. A sample of gaseous combustion by-products is withdrawn from the exhaust stack into the inlet leg conduit and flows to the outlet leg conduit. A portion of the sample is drawn through a convective flow loop conduit and a gas sensing device and back to the outlet leg conduit and therefrom back into the exhaust stack. A counterflow device is positioned in the outlet leg conduit between the exhaust stack and the convective flow loop conduit. The counterflow device includes a portion of the outlet leg conduit that communicates with the exhaust stack and a blowback conduit connected to the outlet leg conduit. A stop member is movably positioned in the blowback conduit. When the fluid pressure in the blowback conduit is greater than the pressure of the gas sample flow, the stop member moves into the outlet leg conduit to block flow to the exhaust stack.

Abstract: A gas analyzer is provided which is comprised of two gas sample flow loops joined at an angle to each other, one being an eductive loop that originates and returns to the chamber or conduit from which a gas sample is to be drawn and the other being a convective loop that joins in fluid flow communication with the eductive loop at a point upstream from its eductor device.

Abstract: A gas analyzer is provided with a common inlet-outlet chamber through which all gases must travel to enter or exit the flow circuit.