Basics of Pinch valves

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 ideally suited for the handling of slurries, liquids with large amounts of suspended solids, and systems that convey solids pneumatically.

 

Construction and Working:

Pinch valve consists of a length of the elastomeric tube fitted with a pinch bar mechanism incorporating a closure stop to prevent over-pinching of the tube. More usually the moulded rubber tube is housed in a metal body which also incorporates the pinching mechanism

The working element of a pinch valve, also known as a clamp valve, is an elastomeric tube or sleeve which can be squeezed at its mid-section by some mechanical system until ultimately the tube walls are pinched or clamped together producing full closure of the flow path.

 

The pinch is applied only to one side of the tube, or a differential screw controlling two pinching mechanisms working in vertical opposition. The latter produces lower-stress working of the tube. With a regulated fluid pressure, the valve may be used for throttling as well as shut-off (full closure).

The particular advantage of the fluid-operated pinch valve is that it will still close tight over entrapped solids, making it particularly suitable for handling products with solids in suspension.

Pinch valves with mechanical pinching mechanisms are normally operated by a handwheel and screw mechanism. but may equally well be driven by a powered actuator in larger sizes

Advantages:

  • Suited for handling slurries and liquid with large amount of suspended solids
  • Can be used for corrosive fluids
  • Low maintenance
  • The flow path is straight without any crevice

Disadvantages:

  • Cannot be used in high pressure/ temperature application
  • Cannot be used for gases

 

 

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