A pinch valve is a simplest valve design. It is a linear motion valve that is used to start, regulate and stop fluid flow. It uses a rubber tube (pinch tube) to control the fluid.
Pinch valves are suitable for on-off and throttling services. However, the effective throttling range is usually between 10% and 95% of the rated flow capacity.
Construction and working:
Pinch valves are ideally suited for the handling of slurries, liquids with large amounts of suspended solids, and systems that convey solids pneumatically.
The pinch control valve consists of a sleeve moulded of rubber or other synthetic material and a pinching mechanism. All of the operating portions are completely external to the valve. The molded sleeve is referred to as the valve body.
Pinch valve bodies are manufactured of natural and synthetic rubbers and plastics which have good abrasion resistance properties. These properties permit little damage to the valve sleeve, thereby providing virtually unimpeded flow. Sleeves are available with either extended hubs and clamps designed to slip over a pipe end, or with a flanged end having standard dimensions.
The flexible elastomer sleeve is compressed by increasing the pressure in the pinch valve body. This creates a lip-shaped closing pattern of the pinch tube. The ensure the pinch valve tightens and restrict the flow through the pipe. The sleeve is allowed to open by releasing the control pressure, that makes to restore the sleeve position.
Advantages:
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Suited for handling slurries and liquid with large amount to suspended solids
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Can be used for corrosive fluids
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Low maintanence
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The flow path is straight without any crevice
Disadvantages:
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Cannot be used in high pressure/ temperature application
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Cannot be used for gases