How to Choose the Right Butterfly Valve Type

1. Concentric Butterfly Valve

• Structure:
  The stem axis, disc center, and pipeline centerline are fully aligned. The disc is positioned at the center of the valve bore, and throughout the entire opening and closing process, the disc edge remains in continuous contact with the valve seat.
• Sealing type:
  A soft-seated design is typically used. Sealing performance mainly depends on the elasticity and recovery characteristics of the seat material.
• Applications:
  Suitable for clean media and operating conditions characterized by ambient or moderate temperatures and low to medium pressure, commonly used in water supply and HVAC systems.

2. Double-Offset Butterfly Valve

• Structure:
  Based on the concentric design, an offset is introduced. The stem axis is shifted relative to the valve body centerline and the disc sealing surface.
• Advantages:
  At the initial stage of opening, the disc disengages from the seat quickly, reducing friction during operation. This helps minimize seat wear and extend service life.
• Applications:
  Suitable for operating conditions with higher pressure, higher cycling frequency, or increased requirements for seat durability.

3. Triple-Offset Butterfly Valve

• Structure:
  A third offset is added to the double-offset design. The disc sealing surface is formed as a conical or inclined profile.
• Advantages:
  During opening and closing, sliding contact between sealing surfaces is completely avoided. These valves typically use metal-to-metal sealing, with the sealing mechanism relying on a wedge effect created by geometry rather than material elasticity.
• Applications:
  Designed for severe service conditions such as high temperature, high pressure, steam, and oil & gas applications. They are not suitable for standard water systems or HVAC applications.

Conclusion

• Concentric butterfly valves:
  Rely on the elasticity of soft (rubber) seats for sealing and are suitable for standard water systems and HVAC applications.
• Double-offset butterfly valves:
  Use an offset design to reduce friction during operation, effectively addressing seat wear and service life concerns.
• Triple-offset butterfly valves:
  Feature metal-to-metal sealing and are designed for high-temperature and high-pressure conditions. They are not intended for typical water system applications.

Butterfly Valve Types by Body Connection

1. Wafer Butterfly Valve

The valve body of a wafer butterfly valve does not include integral flanges. The overall structure is relatively thin, and the valve is installed by clamping it between two pipeline flanges using long through-bolts.

It should be noted that wafer butterfly valves do not provide single-side isolation. The valve is secured only when both flanges are tightened simultaneously, which means this design is not suitable for pipeline ends or applications where downstream piping needs to be removed independently.

Applications:
Thanks to their compact structure and cost advantages, wafer butterfly valves are well suited for continuous pipeline systems that do not require end-of-line isolation, such as water supply mains, circulating water systems, and HVAC networks.

2. Lug Butterfly Valve

The valve body of a lug butterfly valve is equipped with threaded lugs around its outer circumference. Each lug can be bolted independently to the pipeline flange.

Because of this independent bolting arrangement, lug butterfly valves allow single-side pipe removal and end-of-line isolation. During maintenance or inspection, the valve can be closed and the downstream pipeline removed without affecting upstream operation.

Applications:
Pipeline ends, equipment inlets and outlets, or installation locations that require frequent maintenance and inspection.

3. Flanged Butterfly Valve

A flanged butterfly valve features full flanges on both ends of the valve body and is connected directly to the pipeline flanges using short bolts. Compared with wafer and lug designs, this connection method provides higher overall rigidity and structural stability.

This design offers clear advantages in large-diameter or high-stress applications, as it can better withstand pipeline weight, vibration, and additional stresses caused by pressure fluctuations.

Applications:
Large-diameter pipelines, pump stations, main transmission lines, or systems with high requirements for connection stability.

Conclusion

• Wafer butterfly valves:
  The lightest and most cost-effective design, but not suitable for end-of-line isolation.
• Lug butterfly valves:
  Allow single-side pipe removal and are suitable for pipeline ends or locations requiring frequent maintenance.
• Flanged butterfly valves:
  Provide the most secure connection and are suited for large-diameter pipelines and high-stress operating conditions.

Butterfly Valve Types by Seat Material

Valve Seat Material Selection Comparison

Butterfly Valve Types by Operation Method

1. Manual Lever Butterfly Valve

Manual lever butterfly valves feature a simple structure and direct operation. They are typically used on small-diameter pipelines where the valve can be easily operated by hand. For systems with low operating frequency and where on-site manual control is sufficient, lever-operated butterfly valves meet basic flow control requirements.

2. Gear Operated Butterfly Valve

Gear operated butterfly valves use a reduction gearbox to significantly lower operating torque, making manual operation of larger valves—typically DN200 and above—practical. Compared with lever-operated valves, this design not only supports larger diameters but also allows more precise control of opening angle and smoother operation during opening and closing.

3. Pneumatic Butterfly Valve

Pneumatic butterfly valves use compressed air for actuation and are commonly applied in systems requiring interlock control, emergency shutoff, or frequent operation. With fast response and reliable performance, they are well suited for integration with PLC, DCS, and other control systems.

4. Electric Butterfly Valve

Electric butterfly valves are suitable for applications requiring precise position control, remote operation, or where no compressed air supply is available. During selection, particular attention should be paid to power supply conditions, enclosure protection rating, and control mode.

How to Choose the Right Butterfly Valve Type

This selection guide helps you quickly identify the most suitable butterfly valve type based on common application conditions. Final selection should always consider detailed operating requirements.

The essence of butterfly valve selection is not simply matching values in a specification table, but understanding the design intent behind each structure and configuration, as well as their practical limits in real operating conditions. Only when the valve structure, connection type, seat material, and actuation method are properly matched to the system can long-term, stable operation be achieved.

Union Valve has long focused on the design and manufacturing of butterfly valves, covering concentric, double-offset, and triple-offset designs, as well as wafer, lug, and flanged configurations. In real projects, our priority is whether a valve truly fits the operating conditions, rather than whether it merely meets nominal parameters. If you have questions during the selection process regarding valve structure, seat material, or application suitability, Union Valve can provide more targeted technical recommendations based on actual service conditions.

If you have any further questions, please contact us.