Abstract: Radiation detection tube having a glass envelope surrounding an anode and cathode, and having a further conductive surface surrounding a portion of the glass envelope in the region of the anode-cathode gap, the exterior conductor electrically coupled to the anode.

Abstract: Apparatus and method is disclosed for monitoring black liquor recovery boilers to detect the presence of water leakage into the combustion chamber (furnace) of a black liquor recovery boiler, or extinguishing of flame at the black liquor spray nozzles, to release into the furnace at a relatively high rate of speed an absorption agent to collect the water in the furnace and thereby isolate the water from the smelt, and further to provide a medium from which the water may be evaporated to expedite cooling within the furnace without risk of a water/smelt explosive reaction. The apparatus includes propulsion devices for distributing the absorption agent over the furnace smelt, which propulsion devices are controlled by sensors respectively detecting boiler steam pressure, water pressure, and combustion flame. Manual actuation of the propulsion devices is also contemplated by the invention.

Abstract: Apparatus for detecting hazardous radiation with a light sensitive radiation receiving tube enclosed in a housing behind a transparent window, and including an auxiliary internal light source positioned for transmitting light rays into the window and reflecting a portion thereof from the front interface surface of the window back to an internal mirror and to the radiation detection tube for self checking purposes.