A high-pressure check valve is a type of valve that automatically opens and closes the valve disc based on the flow of the medium itself, used to prevent the backflow of the medium. It is also known as a non-return valve, one-way valve, reverse flow valve, or backpressure valve. Check valves are a type of automatic valve, primarily serving to prevent medium backflow, avoid reverse rotation of pumps and drive motors, and release medium from containers. Check valves can also be used in pipelines that supply auxiliary systems where the pressure may exceed the system pressure.

A. Structure and Installation Methods of High-Pressure Check Valves:

1. The valve disc of a high-pressure check valve is disc-shaped and rotates around the axis of the valve seat channel. Due to the streamlined internal channel, the flow resistance is lower than that of lift-type check valves, making it suitable for large-diameter applications with low flow rates and infrequent flow changes. However, it is not suitable for pulsating flow, and its sealing performance is inferior to that of lift-type valves. Butterfly check valves are divided into single-disc, double-disc, and multi-disc types, primarily categorized based on valve diameter to reduce hydraulic impact when the medium stops flowing or reverses.

2. In a high-pressure check valve where the valve disc slides along the vertical centerline of the valve body, the internal thread check valve can only be installed on horizontal pipelines. For high-pressure small-diameter check valves, the valve disc can be spherical. The valve body shape of a butterfly check valve is the same as that of a globe valve (interchangeable with globe valves), resulting in a higher fluid resistance coefficient. Its structure is similar to that of a globe valve, with the valve body and valve disc identical to those of a globe valve. The upper part of the valve disc and the lower part of the valve cover are machined with guide sleeves, allowing the valve disc guide to move freely within the valve cover guide. When the medium flows forward, the valve disc opens under the thrust of the medium; when the medium stops flowing, the valve disc closes under its own weight, preventing backflow. In straight-through butterfly check valves, the inlet and outlet channels are perpendicular to the valve seat channel direction; in vertical lift check valves, the inlet and outlet channels align with the valve seat channel direction, resulting in lower flow resistance than straight-through types.

3. High-pressure check valve: A check valve where the valve disc rotates around a pin within the valve seat. The butterfly check valve has a simple structure, can only be installed on horizontal pipelines, and offers good sealing performance.

4. High-pressure check valve: A valve where the valve disc slides along the centerline of the valve body. Pipeline check valves are a newly developed type of valve, characterized by their small size, light weight, and good manufacturability, representing one of the future directions for check valve development. However, their fluid resistance coefficient is slightly higher than that of swing check valves.

5. High-pressure check valve: This type of valve is used for boiler feedwater and steam shut-off, combining the functions of lift check valves and globe valves or angle valves.

Additionally, there are some check valves not suitable for installation at pump outlets, such as foot valves, spring-type check valves, Y-type check valves, etc.

B. Uses and Performance Specifications of High-Pressure Check Valves:

This valve is used in industrial pipelines to prevent medium backflow.

Performance Specifications

C. Operating Principle and Structural Description of High-Pressure Check Valves:

During use, the medium flows in the direction indicated by the arrow in the diagram.

1. When the medium flows in the specified direction, the valve disc is forced open by the medium. During reverse flow, the valve disc closes due to its own weight and the reverse force of the medium, ensuring a tight seal with the valve seat and preventing backflow.

2. The sealing surfaces of the valve body and valve disc are made of stainless steel overlay welding.

3. The structural length of this valve complies with GB12221-1989, and the flange connection dimensions adhere to JB/T79-1994.