The Georg Fischer Type 578 Butterfly Valve has several beneficial design features unique to the Georg Fischer butterfly valve line. The double eccentric operating principle has an off-center disc and shaft that disengages the disk from the seal with only 3 degrees of rotation. This significantly reduces component wear and required operating torque, as the disk is not in contact with the seal when the valve is opening and closing. Conversely, a traditional boot-style valve has a centric design, significantly increasing the required operating torque because of the disk sealing principle associated with these valves. Boot-style valves often show a far more dramatic increase in required operating toque over time than a double eccentric valve. This can result in premature actuator failure and can even render the valve inoperable. Georg Fischer double eccentric butterfly valves require approximately 50% less operating torque than boot-style competitive valves.
The 578 valve also features a truly non-wetted shaft design. The bushing assembly has a double O-ring seal on both the disk and body sides, providing the highest level of protection and reliability.
