The butterfly check valve is an important fluid control device, mainly used to prevent the backflow of media and ensure the normal operation of the pipeline system. Here is a detailed introduction about the butterfly check valve: 

1. Definition and Alias 

The butterfly check valve, also known as the butterfly-shaped check valve or double-leaf check valve, is a type of valve that automatically opens and closes the valve disc based on the flow of the medium. It also has alternative names such as reverse flow valve, one-way valve, back pressure valve, etc. 

2. Working Principle 

The working principle of the butterfly check valve is relatively simple. When the medium flows in the normal direction, the medium pressure pushes the valve disc to open, allowing the medium to pass through smoothly; while when the medium flows in the reverse direction, the valve disc automatically closes under the action of the medium pressure and its own weight, cutting off the flow of the medium, thereby achieving the purpose of preventing the backflow of the medium. 

3. Structural Characteristics 

Valve disc design: The valve disc of the butterfly check valve is in the form of a circular disc and achieves opening and closing by rotating around the axis. The valve disc can be designed as a single-disc type, a double-disc type, or a multi-disc type to meet the requirements of different pipe diameters. 

Sealing performance: The sealing surfaces of the butterfly check valve can be made by either welding wear-resistant materials onto the body or by using rubber liners, in order to enhance the sealing performance and extend the service life. 

Connection method: Butterfly check valves are typically connected by the flange type, that is, the valve body is directly clamped between two flanges, making the installation simple and quick. 

Fluid resistance: Due to its streamlined design of the internal channels within the valve, the fluid resistance of the butterfly check valve is relatively low. It is suitable for large-diameter applications with low flow rates and where the flow does not frequently change. 

4. Application Scope 

The butterfly check valve is widely used in industrial pipeline systems, especially in situations where it is necessary to prevent the backflow of media. It is suitable for various fluid media and temperature conditions, but it is important to note that its working pressure and temperature range should comply with actual requirements. 

5. Installation and Maintenance 

Installation location: Butterfly check valves are typically installed on horizontal pipelines. They can also be installed on vertical or inclined pipelines as per actual requirements. During installation, it is important to ensure that the direction of the medium flow is consistent with the arrow direction on the valve body. 

Maintenance: Regularly inspect the sealing performance and opening/closing flexibility of the butterfly check valve. Clean the internal dirt and impurities of the valve in a timely manner to ensure its normal operation. 

6. Advantages and Disadvantages 

Advantages: Simple structure, easy to manufacture and maintain. Wide range of applications, suitable for various fluid media and temperature conditions. Quick opening and closing, excellent sealing performance. 

Disadvantages: During the opening and closing process of the valve disc, a large angle of rotation is required, which may cause some noise. The installation position has strict requirements, and it is necessary to ensure that the valve disc can rotate smoothly.