The Difference Between Double Eccentric Butterfly Valves And Central Butterfly Valves
Double eccentric butterfly valves and central butterfly valves are two different designs of butterfly valves commonly used in industrial applications. Here's a breakdown of the differences between the two:
Design:
Double Eccentric Butterfly Valves: These valves have two offsets or eccentricities in their design. The first offset is the shaft offset from the centerline of the valve, and the second offset is the disc seal ring offset from the centerline of the shaft. This design allows the disc to completely disengage from the seat during the opening and closing operation, reducing seat wear and improving sealing performance.
Central Butterfly Valves: Also known as concentric butterfly valves, these valves have a simple and symmetrical design. The shaft is centered in the valve body, and the disc is also centered on the shaft. When the valve is fully open, the disc is parallel to the flow path, and when closed, the disc seals against the seat.
Flow Characteristics:
Double Eccentric Butterfly Valves: The double eccentric design provides better flow characteristics compared to central butterfly valves. By disengaging the disc from the seat, it reduces the interference and turbulence in the flow path, resulting in lower pressure drop and improved flow control.
Central Butterfly Valves: These valves offer moderate flow control capabilities. However, due to the centered disc design, they may cause some turbulence and pressure drop when fully open or partially closed.
Sealing Performance:
Double Eccentric Butterfly Valves: The double eccentric design enhances the sealing performance of the valve. As the disc disengages from the seat during opening and closing, it reduces friction and wear on the sealing surfaces, leading to improved tightness and longer service life.
Central Butterfly Valves: While central butterfly valves provide satisfactory sealing performance, they may experience more wear on the seat and disc due to constant contact during operation.
Applications:
Double Eccentric Butterfly Valves: These valves are commonly used in applications where precise flow control, low pressure drop, and tight shut-off are required. They are suitable for various industries, including oil and gas, chemical, water treatment, and HVAC systems
