A check valve, also known as a check valve or backstop valve, is a valve that automatically stops the backflow of fluid. In industrial fluid systems, check valves play a vital role, they can prevent the backflow of media, pumps and drive motor reversal, as well as the accidental release of container media.
First, according to the material classification
Check valves can be categorized according to their manufacturing materials, mainly including:
Cast iron check valve: made of cast iron, suitable for a variety of fluid environments.
Brass check valve: made of brass, with good corrosion resistance and aesthetics.
Stainless steel check valve: made of stainless steel, suitable for high temperature, high pressure or corrosive fluid environment.
Second, according to the function classification
Check valve can also be categorized according to its function, mainly including:
Silent check valves (such as NRVZ, NRVG, etc.): these valves are designed to reduce the noise of the passage of the fluid, especially suitable for occasions that require a quiet environment.
Standard swing check valves: the valve flap rotates around the rotating axis, with less fluid resistance, suitable for larger caliber pipelines.
Butterfly check valve: structure similar to the butterfly valve, simple and small flow resistance, suitable for a variety of fluid environments.
Diaphragm check valve: using diaphragm as the opening and closing parts, water hammer performance, but the use of temperature and pressure by the diaphragm material restrictions.
In addition, there are rubber flap check valves (SFCV), double flap check valves (DDCV) and other special types of check valves, each of which has its own unique features and applicable scenarios.
Third, according to the structure of the division
From the structural point of view, check valve is mainly divided into three types:
Lift check valve: valve flap along the channel for lifting movement, the action is reliable but the fluid resistance is larger, suitable for small diameter pipeline. Lift check valve can be divided into straight and vertical two, respectively, for horizontal and vertical pipeline.
Rotary check valve: the valve rotates around the axis, the fluid resistance is small, suitable for larger caliber pipelines. According to the number of flaps, rotary check valve can be divided into single, double and multi-valve three.
Butterfly check valves: the structure is similar to butterfly valves, simple and small flow resistance, suitable for a variety of fluid environments.
These check valves are also different in connection form, mainly including threaded connection, flange connection and welding connection.
When choosing check valves, you need to consider the nature of the medium, the size of the pipeline and the pressure level and other factors. Different materials and structures are suitable for different fluid environments. For example, cast iron check valves are suitable for a variety of fluid environments, while stainless steel check valves are more suitable for high temperature, high pressure or corrosive fluid environments.
In the installation of check valves, special attention should be paid to the direction of media flow. The normal flow direction of the medium should be consistent with the direction of the arrow indicated on the valve body, otherwise the normal flow of the medium may be truncated. In addition, for large-diameter or high-pressure pipelines in the check valve, special attention should be paid to its closure may produce water hammer pressure, in order to avoid damage to the valve, pipeline or equipment.
Overall, check valves are an essential and important device in industrial fluid systems. They ensure unidirectional flow of fluids and prevent problems such as backflow and accidental releases. When selecting and installing check valves, full consideration should be given to factors such as the nature of the medium, the size of the pipeline and the pressure level to ensure their proper functioning and long-term effectiveness.