Large valves used on glass furnaces must be specially designed & fabricated to resist thermal damage in the 900-1200 deg F environment of the furnace exhaust. Potential problems for furnace valves are loss of seal through warping of the damper and/or seat, or damage to the valve seat, damper, or frame by thermal erosion and corrosion. Special designs & materials are combined to avoid these problems. In the early days of regenerative furnaces, reversing valves had to be water-cooled. These valves wasted energy, were difficult to maintain & contributed to water pollution because of the chemicals used to treat the cooling water. In the 1960s, high temperature alloys were developed, enabling BlawKnox to manufacture dry type valves. Operators report excellent resistance to warping & thermal deterioration & leakage is said to be 3%, evan after many years of use.
