Butterfly valve types and their own characteristics
Butterfly valves come in various types, each designed for specific applications and environments. They can be classified based on structure, sealing material, sealing method, working pressure, temperature, and connection type.
First, by structure: (1) Central-sealing butterfly valves have a sealing surface that is centered relative to the disc, offering good sealing performance. (2) Single-eccentric sealing butterfly valves feature a slight offset between the disc and the seat, reducing wear and improving durability. (3) Double-eccentric sealing butterfly valves have two offsets, further minimizing friction and extending service life. (4) Triple-eccentric sealing butterfly valves are designed with three offsets, providing excellent sealing even under high-pressure conditions.
Second, by sealing material: (1) Soft-seal butterfly valves use non-metallic materials such as rubber or PTFE for the sealing surfaces, making them ideal for low-pressure and low-temperature applications. (2) Metal-seal butterfly valves use hard metallic materials for both the disc and seat, suitable for high-temperature and high-pressure environments.
Third, by sealing method: (1) Forced-seal butterfly valves rely on external force to create a tight seal. This includes (a) elastomeric seal butterfly valves, where the seal is achieved through the flexibility of the seat or disc, and (b) torque-seal butterfly valves, which use the torque applied to the shaft to generate sealing pressure. (2) Pressure-seal butterfly valves use the elastic properties of the sealing components to maintain a tight seal. (3) Automatic-seal butterfly valves utilize the pressure of the media itself to generate the necessary sealing force, ensuring reliable operation without external input.
Fourth, by working pressure: (1) Vacuum butterfly valves operate under pressures below atmospheric. (2) Low-pressure butterfly valves have a nominal pressure (PN) less than 1.6 MPa. (3) Medium-pressure butterfly valves range from 2.5 to 6.4 MPa. (4) High-pressure butterfly valves operate at PN between 10.0 and 80.0 MPa. (5) Ultra-high-pressure butterfly valves have a nominal pressure greater than 100 MPa.
Fifth, by working temperature: (1) High-temperature butterfly valves function at temperatures above 450°C. (2) Medium-temperature valves operate between 120°C and 450°C. (3) Normal-temperature valves work within the range of 40°C to 120°C. (4) Low-temperature valves are used between -40°C and 100°C. (5) Ultra-low-temperature valves operate below -100°C.
Lastly, by connection type: (1) Wafer-type butterfly valves are installed between two flanges. (2) Flanged butterfly valves connect using flanges. (3) Bellows-sealed butterfly valves use a flexible bellows to provide a leak-proof seal. (4) Welded butterfly valves are permanently attached to the pipeline via welding.
This classification helps engineers and technicians select the most appropriate butterfly valve for their specific application, ensuring optimal performance, safety, and longevity.
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