Sight tube for inspection or measurements - suitable for attaching to the wall of a blast-furnace

摘要

Device for inspecting the interior of a chamber or vessel, consists of (a) an observation or measuring device terminating at the observation end in a very small hole (pref. below 10 mm.) but with a large angular opening (pref. above 60 degrees); (b) a screen placed in front of the observation hole and also possessing a small hole (pref. below 10 mm.); (c) means for circulating a compressed gas, first between the device and the screen, the gas then passing through the hole in the screen; (d) means for the periodic or continuous cleaning of the surface of the screen on the side not facing the device. The device can pref. rotate and tilt to give a wide field of view. Used e.g. as an observation tube fixed on a blast furnace.