Pinch Valves

Pinch valves include any valve with a flexible elastomer body that can be pinched closed, cutting off flow, using a mechanism or fluid pressure. Pinch valves are full bore, linear action valves so they can be used in both an off / on manner or in a variable position or throttling service.  Some typical applications for pinch valves are medical, pharmaceutical, wastewater, slurries, pulp, powder and pellets.  They can effectively control the flow of both abrasives and corrosives, as there is no contact between metal parts and the transport media.

Pinch valves may be closed either by manual means, or fluid actuation. Electromechanical closure is effected by actuating a solenoid, which then lowers a bar or gate onto the sleeve, cutting off the flow.  With fluid actuated pinch valves, the pinching action is accomplished by air or hydraulic pressure placed directly on the elastomer sleeve.  The valve body acts as a built-in actuator, eliminating costly hydraulic, pneumatic, or electric operators.

Pinch valves are used widely in medical, pharmaceutical and other sanitary applications.  They contain a number of design advantages allowing for cleanliness, excellent drainage, and ease of cleaning.  Most varieties are constructed so that the compression pressure is from the top only allowing the valve to drain thoroughly in all positions except upside down. Additionally, many have a straight-through design that allows for a high rate of flow with minimal turbulence.  Both of these features call for low air consumption, allowing for the system to stay relatively closed, reducing the introduction of airborne contaminants. Optional sterility features include end flange configurations that connect flush with the transport tubing; and in situations where the tubing does not connect flush, seals in both the valve and fittings to eliminate particle entrapment, and facilitate in-line cleaning.  Other advantages, not specifically related to sterile operation, include low maintenance, low weight (due to the largely plastic body), and suitability for use in systems requiring explosion-proof line closure.

While the design of pinch valves provides extensive advantages for use in sterile lines, and in situations where product purity is a high priority; these same design features do create some disadvantages.  Due to their elastomeric bodies, pinch valves are not viable in situations where the transport media is of a high temperature.  They are also contraindicated for services that require high-pressure flow, and for use with gases.

• Pinch Valves - Design Principles
  The principle of the pinch valve is extremely simple and adaptable. It works on the same principle as when you pinch the garden hose between your fingers to stop the flow. It is not possible to give a...
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• Larox Valves in Green Liquor Service
  Pinch valves are ideal for the green liquor service as the elastic sleeve ensures that the valve does not jam or clog even if it has been closed for a longer period. The core of a pinch valve is the...
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• Leakproof tubular welds
  Deformation-resistance welding simplifies tube joining. Researchers at Ohio State Univ. used a midfrequency dc 1,200-Hz resistance welder with British Federal WS4004 controller to...
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Part Numbers for Pinch Valves