Double offset butterfly valve is a type of butterfly valve that has a more complex and versatile design compared to the basic butterfly valve. It is characterized by two distinct offsets in the geometry of the valve components, particularly the disc or "butterfly," which sets it apart from the standard butterfly valve. These offsets provide improved sealing capabilities and greater control over flow in various applications.
The double offset design features the following two key offsets:
Eccentric Shaft Offset: The first offset is in the form of an eccentric (off-center) shaft. In other words, the shaft that the butterfly or disc is mounted on is positioned away from the center of the valve body. This offset helps to reduce friction and wear between the disc and the seat, allowing for tighter shut-off and improved sealing.
Eccentric Disc Offset: The second offset involves the shape of the disc itself. The disc is not centered within the valve's circular body; instead, it is offset from the centerline of the pipe. This eccentricity enables the disc to be rotated without rubbing against the valve seat, which minimizes wear and allows for a tighter seal.
The benefits of a double offset butterfly valve include:
Enhanced Sealing: The eccentric disc and shaft offsets reduce friction and wear, improving the sealing capabilities of the valve. This is particularly important in applications where a secure shut-off is critical.
Low Torque and Wear: The reduced friction in the design means that it requires less torque to operate the valve. It also results in less wear on the valve components, extending the valve's lifespan.
High Performance: Double offset butterfly valves are capable of handling high-pressure and high-temperature applications, making them suitable for a wide range of industries, including oil and gas, petrochemical, power generation, and more.
Bubble-Tight Shut-Off: Double offset butterfly valves can achieve bubble-tight shut-off, which is a critical requirement in industries where even small leaks are unacceptable.
Versatility: They can be used in both on/off and throttling (control) applications, offering a versatile solution for flow control.
Double offset butterfly valves are often used in applications where precise flow control, high-pressure handling, and a secure shut-off are necessary. They are commonly employed in industries where process fluid control is crucial, such as in the oil and gas industry, power generation, chemical processing, and water treatment.
