What is a Double Eccentric Butterfly Valve?

November 06, 2024
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The double eccentric butterfly valve, also known to as a high-performance butterfly valve, is an advanced design based on the single eccentric butterfly valve. Its structural distinction lies in the shaft axis being offset from both the center of the disc and the body. This valve is especially suited for drainage systems in facilities such as water plants, power stations, steel mills, chemical plants, and environmental engineering projects. It performs exceptionally well in waterway pipelines, serving as a reliable device for flow regulation and shut-off.

Structural Characteristics of Double Eccentric Butterfly Valve

The defining feature of a double eccentric butterfly valve is its dual offset—where the shaft axis is positioned away from both the disc center and the body center. This design allows the disc to quickly disengage from the seat upon opening, significantly reducing unnecessary compression and friction between the disc and the seat. This feature not only minimizes operating torque and wear but also extends the lifespan of the seat. Additionally, the double eccentric design enables the use of a metal seat, enhancing its suitability for high-temperature applications.

Operating Principle of Double Eccentric Butterfly Valve

The double eccentric butterfly valve operates through the rotation of the shaft, which drives the disc to open or close, thus controlling the fluid medium. Due to its unique double eccentric design, the valve offers enhanced precision and stability in flow regulation and shut-off functions, making it a preferred choice for applications requiring high accuracy and durability.

Difference Between Double Eccentric, Concentric, and Triple Eccentric Butterfly Valves

The-difference-between-double-eccentric-butterfly-valve-and-other-butterfly-valves

	Concentric Butterfly Valve	Double Eccentric Butterfly Valve	Triple Eccentric Butterfly Valve
Design	The centerline of the stem and disc is aligned with the centerline of the valve body.	The stem axis is offset from both the disc center and the body center.	The first two offsets are the same as the double eccentric valve; the third offset is the angular displacement of the sealing surface center from the horizontal axis.
Sealing Performance	The disc compresses the soft seal to achieve sealing, ensuring sealing performance.	The double eccentric design creates a cam effect during operation, tightening the soft seal, providing relatively good sealing.	Does not rely on the elasticity of the seat; instead, it achieves sealing through surface contact pressure, allowing for zero leakage.
Operating Torque	Relatively large	Smaller	Smaller
Seal Surface Wear	Subjected to compression and scraping, leading to faster wear.	Eliminates unnecessary compression and scraping, reducing wear.	Almost no wear.
Applicable Temperature Range	Low and medium temperature	Medium and high temperature	High temperature
Cost	Relatively low cost	Moderate cost	Relatively high cost

If you are looking for a powerful valve product capable of handling complex water treatment projects, consider the double eccentric butterfly valve from Union Valve.The following are the advantages of our double eccentric butterfly valve

Advantages of the Double Eccentric Butterfly Valve

1.Reliable Sealing with No Leakage
The unique design of the double eccentric butterfly valve creates a cam effect during operation, compressing the soft seal and reducing friction between the disc and the seat. This extends the seal's lifespan, ensures tight closure, and makes it suitable for high-pressure and high-temperature environments.

2.Rational Design and Easy Maintenance
The double eccentric butterfly valve's disc has a frame structure with high strength, a large flow area, and low flow resistance. The overall coating prevents rust, and the rubber seal ring can be positioned on either the valve body or the disc, allowing users to choose based on the medium's properties. The standard configuration is an EPDM valve disc seal ring, but NBR or VITON can be selected as alternatives. The seal ring is easy to replace, making it adaptable for various media.

3.Excellent High Strength
The valve body and disc are made from GGG40/50 ductile iron, providing outstanding impact resistance and tensile strength.

4.Bidirectional Sealing
The double eccentric butterfly valve generally has a bidirectional sealing function, allowing sealing in both directions and enhancing system safety.

5.Wide Application Range
It can be used across various temperature and medium conditions, with a temperature range from -20°C to +425°C. It is compatible with water, steam, oil, air, gas, and many other media.

6.Compact Structure and Space-Saving
The butterfly valve has a simple structure, small size, and lightweight design, making it convenient for pipeline arrangement and installation, saving space.

7.Comprehensive Protection with Corrosion Resistance
The surface features a CS epoxy coating that effectively isolates moisture, chemicals, and air from the carbon steel, providing excellent wear resistance. This enhances the valve's lifespan in corrosive environments. The epoxy coating improves corrosion and wear resistance, reducing maintenance and replacement frequency, thereby lowering long-term operational costs.

Maintenance of Double Eccentric Butterfly Valve

1.Regular Inspection of Seals
Regularly inspect the sealing surfaces of the valve seat and disc to ensure they are free from wear, scratches, or other damage that could lead to leakage. If the sealing surface shows significant wear, replacement or regrinding may be necessary to restore its sealing effectiveness.

2.Lubricate the Stem
Periodically lubricate the stem and its connections to reduce friction and wear, ensuring smooth operation. The choice of lubricant should match the operating conditions and temperature. Pay special attention to the stem’s threaded sections to prevent rust from impacting the valve's opening and closing performance.

3.Test Opening and Closing Performance
Regularly test the valve's opening and closing function to ensure it operates smoothly without any jamming. If the operation is not smooth, check for foreign objects or internal component damage.

4.Professional Inspection and Calibration
Schedule periodic inspections and calibration by professional technicians, especially in environments where there are large fluctuations in pressure or temperature, to ensure stable performance.

The double eccentric butterfly valve excels in various industrial applications due to its outstanding performance and versatility.

If you are looking for a high-efficiency, reliable double eccentric butterfly valve, feel free to contact Union Valve. Our series of double eccentric butterfly valves is designed for efficient and dependable fluid control across multiple industrial scenarios, including HVAC systems, water treatment, food and beverage processing, chemical processing, paper production, and shipbuilding.