Centerline Butterfly Valve
The structural feature of the centerline butterfly valve lies in the complete alignment of the valve shaft, disc center, and valve body center, with no eccentric design. The sealing surface typically uses soft materials (e.g., rubber or PTFE), achieving sealing through disc compression.
Advantages:
Simple and intuitive structure with relatively low manufacturing costs.
Excellent sealing performance under low-pressure and room-temperature conditions (near zero leakage).
Low operating torque for smooth and lightweight on/off operation.
Disadvantages:
Vulnerable seat material wear; unsuitable for high-temperature/pressure environments.
Not recommended for media containing particles or corrosive components.
Applications:
Primarily used for clean fluids (water, air, gas) in low-pressure (≤PN10) and moderate-temperature (≤120°C) systems. Common in:
Municipal water supply
HVAC refrigeration
Food processing pipelines
Double Offset Butterfly Valve
The double offset butterfly valve combines two eccentricities:
First offset: The valve shaft is offset from the disc center to reduce friction during operation.
Second offset: The shaft is further offset from the valve body's sealing center, enabling quick disengagement during opening/closing.
Sealing surfaces may use soft seals or metal hard seals.
Advantages:
Lower operating torque than centerline valves, extending service life.
Tolerates higher pressure/temperature conditions.
Disadvantages:
Sealing performance under high pressure may be inferior to triple offset valves.
Applications:
Suitable for medium-low pressure (PN16–PN25) and medium-temperature (≤200°C) liquids/gases. Common in:
Wastewater treatment
Chemical plants
Power industry pipelines
Triple Offset Butterfly Valve
The triple offset butterfly valve features three eccentricities:
First two offsets: Identical to double offset valves (shaft offset from disc + radial offset).
Third offset: The seat sealing surface adopts a tapered angle (conical offset), achieving line contact sealing.
Sealing surfaces typically use metal hard seals (e.g., stainless steel/alloy steel) for high-temperature/pressure/corrosive resistance.
Advantages:
Near-zero friction during operation, minimizing torque and maximizing lifespan.
Withstands extreme conditions: high temperature (≤600°C), high pressure (≥PN100), and corrosive media.
Bidirectional sealing performance rivals gate/globe valves.
Disadvantages:
Complex structure increases manufacturing costs.
Requires ultra-high machining precision.
Applications:
Designed for critical systems with harsh conditions (steam, oil/gas, acids/alkalis). Common in:
Petrochemical plants
Nuclear power
Shipbuilding
Metallurgical industries
