Pinch valves are used for a variety of applications. They are an excellent option for controlling the flow of slurries and other granular products. They are also known for their ease of use and durability.
Pneumatic pinch valves are designed to be operated by compressed air, a mechanical device or by handwheel control. They are made up of a sleeve, a clamping bar and an end connection. The sleeve can be either linear or rubber, depending on the application.
The sleeve material is chosen carefully to withstand the media it will be handling. Synthetic polymers that are abrasion and corrosive resistant are commonly selected for pinch valve sleeves. Common types include EPDM, nitrile, natural rubber, food-grade rubber, GRS, PTFE and neoprene.
Tubing materials for pinch valves are generally elastomeric. The sleeve material and the tubing material must be compatible with one another. Ideally, elastomeric tubing materials should have a long life rating and not wear out quickly.
Stainless steel is a popular choice for a pinch valve body, but other materials are available as well. For example, aluminum is an economical choice for a pinch valve body. The end covers/flanges of a pinch valve can be made of aluminum, steel or plastic.
A pinch valve works by a rubber sleeve that is pressurized to create an occlusion between the two opposing pinching surfaces. This occlusion creates a flow blockage. This occlusion is controlled by an air nipple located on the outside of the valve. When the operator turns the handwheel, this nipple presses down on the valve sleeve, closing it.
In the closed position, the sleeve is flattened and has a specified lipped fold pattern that seals the fluid flow. This allows for the complete sealing of solids and slurries.
The sleeve is usually made of natural rubber, but other rubber qualities are available, including EPDM, nitrile, Viton and neoprene. Sometimes, a polyurethane coating or fiber is added to the sleeve for extra abrasion resistance and strength.
There are several types of pinch valves, including open, enclosed, and mechanically closed. Each type is designed for specific applications.
Choosing the right valve for your application is critical to the success of your project. Various factors must be taken into account before making a decision, including the application, the flow media, and the operation temperature.
What is the difference between mechanically and pneumatically closed pinch valves?
The mechanically closed pinch valve is typically less expensive than the pneumatically closed version. However, it is not suitable for vacuum applications because the sleeve can collapse due to suction.
Pinch valves are designed for low-pressure applications, so they can be used with a wide range of pipe sizes and types. They are not ideal for high-pressure applications, but they are still a good option for many types of slurries and other corrosive and abrasive materials.
Pinch valves are a simple, low-cost, easy-to-operate and cost-effective alternative to conventional valves such as knife gate sliding valves, butterfly valves and ball valves. They are widely used in a wide range of industrial applications for slurries, powder, pellets, and other granular materials.