By When you need a valve that can handle corrosive media, powders, and granular materials, a pinch valve is a perfect solution. These versatile valves have a full bore and a tight shut off for effective flow control. They are used for a variety of applications, from liquids to powders to slurries. They are also safe, reliable, and economical. They are widely used in a variety of industries, from medical instruments to clinical analyzers.
The body of a pinch valve is typically made of natural rubber or silicone. For external pinch valves, the tube is generally made from flexible PVC. However, other types of tubing may be employed. For example, elastomeric tubing can be more durable. The material should have adequate abrasion resistance to allow little wear on the valve sleeve.
The main components of a pinch valve are the internal rubber sleeve, the actuation mechanism, and end connectors. The sleeve is the only part of the valve that actually comes into contact with the media. If the sleeve is damaged, it will be unable to close properly. The sleeve can be made of a wide variety of materials, including NBR (nitrile) or silicone.
To make the pinch valve operate, the sleeve is pushed down by compressed air. Once the sleeve is pushed to the bottom of the valve, the actuation force causes the tube to be closed. The amount of force required will depend on the size of the pipe and the conditions in which it is being operated.
A pinch valve’s actuation mechanism is designed to provide a pinching action that pinch valve interrupts the fluid flow. This action is done by applying pressure to a rubber sleeve. As the sleeve is pushed back, the pinching bars inside the pinch valve squeeze into the center of the valve, forming a tight shut off around the trapped particles. The pinch valve is designed to provide a maximum opening of about 0.75mm.
A pinch valve sleeve is usually abrasion resistant, and is therefore able to withstand the abrasive effects of cement and slurries. It is often reinforced with fiber or rubber to increase its strength and durability. It is commonly available in food grade. If it is not, abrasion resistant lining may be added to the sleeve for additional protection.
A pinch valve is usually actuated by a handwheel or a motor. An electric motor is most common, but a pneumatic mechanism is also available. Normally, the handwheel is operated by a torque generated by the motor, making it semi-automatic or automatic.
A pinch valve’s main function is to control the flow of media, and its shape is designed to keep the moving parts outside the media stream. This allows the valve to obstruct the flow without requiring packing.
Because pinch valves have smooth walls, they minimize turbulence, and allow for easy bubble tight shutoff. Their design is particularly ideal for processes in which the media cannot be in contact with the process media. Nevertheless, pinch valves are not suitable for vacuum or high-pressure applications.
