Butterfly Valve

Working Principle of Butterfly Valves

Butterfly valves operate by rotating the valve stem to drive the valve disc (i.e., butterfly plate) to rotate within the valve body, thereby achieving the functions of opening, closing, or regulating fluid flow. When the butterfly plate is parallel to the fluid flow direction, the valve is fully open; when the butterfly plate is perpendicular to the fluid flow direction, the valve is fully closed. Butterfly valves typically only require a 90° rotation to complete full opening or full closing operations, thus featuring rapid opening and closing capabilities.

Main Structure of Butterfly Valves

1. Valve Body: The basic component of a butterfly valve, used to connect pipes and house internal components.

2. Butterfly Disc (Valve Disc): The core component, which controls the flow state of the fluid through rotation.

3. Valve Stem: Connects the actuator to the butterfly disc and transmits rotational power.

4. Sealing Components: Ensure sealing performance when the valve is closed. Common materials include rubber, PTFE, etc.

5. Drive Mechanism: Manual, electric, pneumatic, or hydraulic drive mechanisms used to control the rotation of the butterfly disc.

Classification of Butterfly Valves

Based on different characteristics, butterfly valves can be classified into the following categories:

1. By structural form:

o Centreline butterfly valve: The butterfly disc is located at the centre of the valve body, suitable for low-pressure and normal-temperature conditions.

o Eccentric butterfly valve: Divided into single-eccentric, double-eccentric, and triple-eccentric butterfly valves, suitable for high-pressure and high-temperature conditions.

2. By connection method:

o Flanged butterfly valve: Connected to the pipeline via flanges.

o Wafer-type butterfly valve: Secured between two sections of pipeline using bolts.

o Welded butterfly valve: Directly welded to the pipeline, suitable for high-pressure or special conditions.

3. By sealing type:

o Soft-seal butterfly valve: Uses elastic materials as sealing elements, offering good sealing performance but limited temperature and pressure resistance.

o Hard-seal butterfly valve: Uses metal seals, suitable for high-temperature and high-pressure environments.

Applications of Butterfly Valves

1. Water Treatment Industry: Used for regulating water flow and controlling pressure, commonly found in scenarios such as water treatment plants and sewage treatment plants.

2. Petrochemical Industry: Suitable for pipeline systems transporting oil, gas, and other media.

3. HVAC Systems: Used for flow regulation and on/off control in heating and cooling systems.

4. Power Industry: Used for fluid control in cooling water systems, steam pipelines, and other applications.

5. Food and Pharmaceutical Industry: Sanitary-grade butterfly valves meet the cleanliness requirements of food and pharmaceutical production processes.

Advantages and Limitations of Butterfly Valves

Advantages:  

• Compact structure, occupies minimal space.  

• Rapid opening and closing, easy to operate.

• Low fluid resistance and low energy consumption.

• Lower cost and simple maintenance.

Limitations:

• Sealing performance is slightly inferior to that of ball valves.

• Prone to leakage under high pressure differential conditions.

• Not suitable for prolonged partial opening, as it may cause wear on the sealing surfaces.

In summary, butterfly valves play an important role in modern industrial and civil applications due to their excellent cost-effectiveness and wide applicability. Selecting the appropriate butterfly valve type and specifications can significantly improve the operational efficiency and reliability of fluid systems.