In modern water supply and drainage networks, large-diameter valves face a constant battle against friction, wear, and high operating torque. Traditional concentric butterfly valves, while widely used, have a significant drawback: their disc constantly rubs against the seat throughout the entire 90-degree rotation. This continuous friction not only requires higher torque to operate but also leads to premature seat wear, frequent maintenance, and eventual leakage.
To solve these engineering challenges, the Double Eccentric Butterfly Valve (also known as a high-performance butterfly valve) was developed. By incorporating two distinct offsets—one behind the disc sealing surface and one from the pipe centerline—this advanced valve creates a unique cam-like motion. As the disc rotates, it engages with the seat only during the final few degrees of closure and disengages immediately upon opening.
This “lift-off” effect is a game-changer. It virtually eliminates friction and wear between the disc and the seat, resulting in significantly lower operating torque, smoother throttling, and a service life that far exceeds conventional designs. With a pressure range from PN2.5 up to PN40 and an impressive diameter range of DN100 to DN3000, the double eccentric butterfly valve is engineered for everything from low-pressure gravity lines to high-pressure transmission mains.
In this guide, we will explore the working principles, key functions, and outstanding advantages of double eccentric butterfly valves, helping you understand why they are the preferred choice for demanding water system applications, including municipal trunk mains, pump stations, and raw water intakes.
A Double Eccentric Butterfly Valve (also known as a high-performance butterfly valve) is an advanced quarter-turn flow control device that incorporates two offsets (eccentricities) in its design, distinguishing it from conventional concentric butterfly valves.
The two eccentricities are:
|
Eccentricity |
Description |
|
First Eccentricity |
The valve stem is positioned behind the centerline of the disc sealing surface (offset from the disc centerline). |
|
Second Eccentricity |
The valve stem is offset from the pipe/valve centerline (offset from the body centerline). |
These dual offsets create a cam-like motion when the valve operates. As the disc rotates, it engages with the seat only during the final few degrees of closure and disengages immediately upon opening. This lift-off effect significantly reduces friction and wear between the disc and the seat, resulting in longer service life, lower operating torque, and superior sealing performance.
Unlike concentric (zero-offset) butterfly valves where the disc constantly rubs against the seat throughout the entire 90-degree rotation, the double eccentric design ensures that the disc contacts the seat only when fully closed, making it ideal for higher pressures, higher temperatures, and demanding water system applications.
At WEIZIDOM, our Double Eccentric Butterfly Valves are manufactured with strict quality control (12 tests from raw material to final product) and comply with GB/T12238 design standards, ensuring reliable performance in water supply and drainage systems.
In water supply and drainage systems, the Double Eccentric Butterfly Valve serves as a high-performance, durable, and low-maintenance flow control device for demanding applications where conventional butterfly valves may wear prematurely. Its primary functions include:
|
Function |
Description |
|
Flow Isolation |
Provides reliable bubble-tight shut-off for pipeline sections, allowing safe maintenance, repair, or replacement of downstream components. |
|
Flow Regulation (Throttling) |
Excellent for precise flow control in pressure reducing stations, flow balancing, and process control applications — the double eccentric design provides smoother modulation with less vibration. |
|
High-Pressure Isolation |
Capable of handling higher pressure ratings (up to PN40) than conventional concentric butterfly valves, suitable for pressurized water transmission mains. |
|
Large-Diameter Flow Control |
Available up to DN3000, making it ideal for large-scale water supply trunk mains, raw water intakes, and major drainage outfalls. |
|
Pump Station Control |
Installed at pump suction and discharge lines to start, stop, or regulate flow, with lower torque requirements for easier operation. |
|
Emergency Shut-Off |
Quarter-turn operation enables rapid closure in emergency situations, protecting equipment and preventing backflow. |
|
Distribution Network Sectioning |
Divides large water distribution networks into manageable zones for pressure management and leak detection — the long cycle life handles frequent operation. |
|
Raw Water Intake Control |
Suitable for raw water containing sand or sediment, as the lift-off design reduces abrasion on sealing surfaces. |
Typical applications within water supply and drainage include:
✔ Municipal water supply trunk mains
✔ Raw water intake lines from rivers, lakes, or reservoirs
✔ Water treatment plant inlet and outlet lines
✔ Pumping station suction and discharge
✔ Pressurized water transmission pipelines (up to PN40)
✔ Large-diameter drainage and stormwater outfalls
✔ Industrial water supply and cooling water circuits
✔ Irrigation district main canals and pipelines
WEIZIDOM’s Double Eccentric Butterfly Valve is engineered for high performance, long service life, and reliable operation in water supply and drainage systems.
|
Feature |
Advantage |
|
Double Eccentric Design |
The dual offset creates a cam-like lift-off action — disc contacts the seat only at full closure, eliminating continuous friction and reducing wear by over 80% compared to concentric designs. |
|
Bubble-Tight Shut-Off |
Metal or resilient seat with double eccentric geometry achieves zero leakage (meeting GB/T12238 requirements), providing reliable isolation for critical water system sections. |
|
Low Operating Torque |
Reduced friction between disc and seat means lower torque requirements — allows manual operation even in larger diameters and reduces actuator size/cost for automated systems. |
|
Long Service Life |
Minimal seat wear due to lift-off design results in significantly longer cycle life — ideal for applications requiring frequent operation (e.g., pressure management, daily throttling). |
|
High Pressure Capability |
Pressure range from PN2.5 to PN40 — suitable for everything from low-pressure gravity lines to high-pressure transmission mains. |
|
Extra-Wide Diameter Range |
Available from DN100 to DN3000, covering medium to ultra-large water system pipelines. |
|
Multiple Material Options |
Valve body and disc available in Ductile Iron (cost-effective, good strength), Cast Steel (higher pressure/temperature), and Stainless Steel (maximum corrosion resistance) — choose based on water quality and pressure requirements. |
|
Bi-Directional Sealing |
Seals effectively against pressure from either direction, simplifying installation and eliminating orientation concerns. |
|
Quarter-Turn Operation |
90° rotation from fully open to fully closed enables fast response — ideal for emergency shut-off and automated control systems. |
|
Excellent Throttling Performance |
The double eccentric geometry provides stable flow characteristics with minimal cavitation and vibration, making it superior to concentric valves for modulating service. |
|
Fugitive Emission Control |
Advanced stem sealing with multiple packing rings and live-loading options (available) prevents leakage to the atmosphere — important for environmental compliance. |
|
Actuator Ready |
Top flange conforms to ISO 5211 standards, allowing direct mounting of manual gear operators, electric actuators, pneumatic actuators, or hydraulic actuators. |
|
Easy Maintenance |
The design allows seat and disc replacement without removing the valve body from the pipeline (on most configurations) — reduces downtime and maintenance costs. |
|
Anti-Blowout Stem Design |
Stem is mechanically retained to prevent accidental blowout under high pressure, ensuring operator safety. |
The Double Eccentric Butterfly Valve represents a major leap forward in flow control technology for water supply and drainage. By utilizing a dual-offset geometry, it transforms the way the disc interacts with the seat—reducing friction by over 80%, lowering operating torque, and ensuring bubble-tight shut-off even under high pressures (up to PN40).
When selecting a butterfly valve for your project, consider these key factors:
For standard, low-pressure applications where cost is the primary driver, concentric butterfly valves may suffice.
For high-pressure, large-diameter, or frequently operated systems (such as pump stations, transmission mains, and pressure reducing stations), the double eccentric design is the superior choice. Its lift-off action provides excellent throttling performance with minimal cavitation and vibration, and its long cycle life ensures decades of reliable, low-maintenance operation.
At WEIZIDOM, our Double Eccentric Butterfly Valves are manufactured to strict GB/T12238 standards and are available in ductile iron, cast steel, and stainless steel to match your specific water quality and pressure requirements. With actuator-ready top flanges (ISO 5211) and anti-blowout stem designs, they are built for safety and ease of automation.
Don’t let valve wear and high torque slow down your operations.
Contact WEIZIDOM today to discuss your specific requirements, request a technical consultation, or get a customized quote for your next water system project.
