What Is A Concentric Butterfly Valve?

A concentric butterfly valve is an industrial valve used for pipeline shut-off and flow regulation. It helps improve the efficiency of piping systems and is also known as a center-sealed butterfly valve.

Table of Contents

1. Definition

2. Main Components

3. Working Principle

4. Structure & Features

5. Connection Types

6. Body & Seat Material Selection

7. Actuation Methods

8. Key Advantages

9. Conclusion

Keywords: Butterfly valve, Concentric butterfly valve, Advantages

Watch the following videos for a quick overview:

https://youtube.com/shorts/uXt_OHadD3Q

https://youtube.com/shorts/OTvLXxd6he8

I. Main Components of  Concentric Butterfly Valve

The valve mainly consists of the following four parts:

1. Valve Body: The main structure of the valve, typically made of ductile iron or stainless steel, with a rubber-lined seat.

2. Disc: A rotating plate located at the center of the pipeline, acting as the flow control element. Its surface is usually polished to reduce friction.

3. Seat: An elastic sealing ring (such as EPDM or PTFE) that ensures tight shut-off and zero leakage.

4. Stem: A shaft that passes through the disc and transmits torque from the actuator to the disc.

II. Working Principle

The operation is simple and intuitive:

When the actuator (handle, gearbox, or actuator) rotates the stem, the disc rotates accordingly:

Open Position: The disc is parallel to the flow, resulting in minimal resistance.

Closed Position: The disc rotates 90° and presses tightly against the elastic seat, achieving a zero-leakage seal.

III. Structure & Features

Structural Characteristics

In a concentric butterfly valve, the stem axis, disc center, and body centerline are aligned. This central alignment allows the disc to evenly compress the seat, ensuring a 360° uniform sealing effect.

Key Features

1. Symmetrical Design: Provides bidirectional sealing performance, allowing flow in either direction.

2. Soft Sealing Design: Uses elastic materials such as EPDM, NBR, or PTFE.
Advantages: Excellent sealing performance and low operating torque.
Limitations: Not suitable for high-temperature (>150°C) or high-pressure applications.

3. Compact Structure: Fewer components, lightweight design, and easy installation.

4. Anti-Blowout Stem: Enhances safety by preventing the stem from being ejected under pressure.

Connection Types

Depending on installation requirements, there are three main types:

Wafer Type: Installed between two flanges using bolts; lightweight and compact.

Flanged Type: Equipped with flanges for secure connection, suitable for large diameters.

Lug Type: Features threaded inserts, ideal for systems requiring downstream disassembly.

IV. Body & Seat Material Selection

1. Valve Body Materials

• Stainless Steel: Excellent corrosion resistance

• Ductile Iron: High strength and cost-effective

• Carbon Steel: Suitable for general industrial use

2. Seating Materials

Ⅴ. Actuation Methods

Various actuation options are available:

Handle: Ideal for small diameters, simple manual operation.

Gearbox: Provides higher torque for large valves.

Pneumatic Actuator: Fast response, widely used in automation systems.

Explosion-Proof Electric Actuator: Suitable for hazardous environments with precise control.

Ⅵ. Why Choose a Concentric Butterfly Valve?（Key Advantages）

• Cost-Effective: Ideal for low to medium pressure applications

• Easy Operation: Stable and low torque performance

• Low Maintenance: Replaceable seat extends service life

• Wide Applications: Water supply, wastewater treatment, HVAC, and industrial systems

Ⅶ. Conclusion

With flexible material combinations and multiple actuation options, concentric butterfly valves can meet most low- to medium-pressure flow control requirements. When selecting a valve, always consider the medium temperature, pressure, and automation needs.