Abstract: A window for viewing combustion includes a window body having an interior surface facing a combustion space, an opposed exterior surface facing an instrument space, and a seal surface between the interior and exterior surfaces. The seal surface tapers from the interior surface to the exterior surface and hermetically separating the instrument space from the combustion space. A coupling for connecting a combustion space to an instrument space includes a union body, flanged body and locking body all aligned along an optical axis. The union body defines a tapered bore in which a viewing window for viewing combustion is disposed.

Abstract: An infrared emittance combustion analyzer utilizing detectors in a flame burner which monitor the radiation at two preselected wavelengths. The respective radiation signals are filtered to eliminate DC signal variations, rectified and converted into a DC value which is representative of the measured radiation signals. The respective DC values are formed into a ratio which is compared against a predetermined setpoint signal, and the error signal resulting from this comparison is utilized to drive an electromechanical controller which adjusts either the air damper or the fuel damper to adjust the fuel/air mixture which is fed into the burner.