High performance butterfly valve

A high-performance butterfly valve has a disc that is offset from the shaft centerline. This eccentricity causes the seating surface to move away from the seal once the disc is out of the closed position, reducing friction and seal wear. It is also known as an eccentric disc valve the advantage of the butterfly valve is improved shutoff while maintaining... 

The high performance butterfly valve operates like aU butterfly valves with a disk mounted in the middle of the valve that is rotated to open and close the valve. The high performance butterfly is designed with a more complex disk assembly often called "double offset." The first offset is done by locating the stem downstream of the centerline of the disk. This allows an unobstructed 360-degree sealing surface. The second offset moves the stem off the vertical axis of the disk. The combination moves the disk quickly away from the seat as the stem is rotated. This is done to reduce operating torque and extend seat life. 

The high performance butterfly valve is available with a variety of seat materials including soft elastomer, polymer or metal (Figure 11-3). This design will t q)ically withstand higher pressures and higher operating temperatures. 

High-performance butterfly valves and gate valves are recommended for block... 

Firesafe valves should be used to isolate reactors, storage vessels, and pipelines. They can be used wherever EBVs are required. With the increase in popularity of automated plants, quarter-turn valves are very popular and are used in most installations. The only common quarter-turn valves that are available as completely firesafe valves are ball valves and high-performance butterfly valves. For special purposes, there are other special firesafe valves. 

Butterfly and diaphragm valves are other options. Butterfly valves can be lined with an elastomer or a fluorocarbon resin. Soft-seated, high-performance valves have higher pressure ratings but allow contact of the process fluid with the metal. 

---