Glass ribbon float tank with a pyrometer assembly having a heated viewing tube and method of use
A viewing tube extension for an infrared radiation pyrometer includes a tube having a heater therein. The heater has a passageway so that the pyrometer sights a glass ribbon moving through a forming chamber of a flat glass making apparatus. Vapors from the heating chamber moving into the tube are maintained above their dew point as a purge gas moves the vapors out of the tube.