The sensing device is a light level indicator that comprises a light sensitive element such as a photo resistor, associated detection circuitry and "go" and "no go" indicator lights which determine whether the level of illumination is above or below a predetermined acceptable level for a given area being tested. The device may be constructed with two light sensitive elements one for sensing direct light and the other for sensing reflected light, or alternatively, the device may have only either element. A multi-position switch may also be provided which can be set at any one of a number of different threshold levels. An adapter is used with the device for checking the calibration of the device. This adapter comprises a radioactive source, holder and a mask which is periodically replaced for maintaining the source at a constant light output.
A flame scanning system for monitoring a combustion process by detecting flame emission characteristics in the ultraviolet light spectrum. A metered relative flame intensity signal, flame-off signal, and flame-on signal are provided. A self-diagnostic feature produces a flame marginal signal indicative of substandard flame operation; a tube marginal signal indicative of imminent UV tube failure is also produced. A scanner shutter mechanism includes a check failure feature for detecting UV tube failure. An electronic assisted sighting indicator is also included to assist during on-sight scanner positioning and to provide optimum scanner placement.
