A pinch valve is a full bore or fully ported type of control valve which uses a pinching effect to obstruct fluid flow.

Operating principle

Pinch valves employ an elastic tubing (sleeve/hose) and a device that directly contacts the tubing (body). Forcing the tubing together will create a seal that is equivalent to the tubing's permeability. Air-operated pinch valves consist of an elasticised reinforced rubber hose, a type of housing, and two socket end covers (or flanges). In air-operated pinch valves, the rubber hoses are usually press-fitted and centered into the housing ends by the socket covers. There is no additional actuator, the valve closes as soon as there is a pressurized air supply into the body. When the air supply becomes interrupted and the volume of air exhausts, the elastic rubber hose starts to open due to the force of the process flow.

Fields of application

Pinch valves are typically used in applications where the media needs to be completely isolated from any internal valve parts. The sleeve will contain the flow media and isolate it from the environment hence reducing contamination. They are commonly applied to medical instruments, clinical or chemical analyzers, and a wide range of laboratory equipment. Pinch valves are also used for slurries or processes with entrained solids, because the flexible rubber sleeve closes droptight around solids. This avoids entrapment by the seat or in crevices, which would happen if using globe, diaphragm, butterfly, gate or ball valves. Major industries that use pinch valves are: *

Bulk Bulk can refer to: Industry * Bulk cargo * Bulk liquids * Bulk mail * Bulk material handling * Bulk pack, packaged bulk materials/products * Bulk purchasing * Baking * Bulk fermentation, the period after mixing when dough is left alone to f ...

and solids handling, *

Cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...

industry, *

Waste water Wastewater is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of domestic, industrial ...

industry, *

Chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., w ...

industry, * Food industry, *

Beverage A drink or beverage is a liquid intended for human consumption. In addition to their basic function of satisfying thirst, drinks play important roles in human culture. Common types of drinks include plain drinking water, milk, juice, smoo ...

industry, *

Ceramic A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...

Glass Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling ( quenching ...

Plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...

industry On a smaller scale, pinch valves are used in some

water pistol Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a s ...

s, notably the original

Super Soaker Super Soaker is an American brand of recreational water gun that uses manually-pressurized air to shoot water with greater power, range, and accuracy than conventional squirt pistols. The Super Soaker was invented in 1989 by engineer Lonnie Joh ...

50.

Advantages

The most important benefits of using pinch valves are the full bore for the flow media, and 100% tight shut off – even on solids such as granules,

powder A powder is a dry, bulk solid composed of many very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms ''powder'' and '' granular'' are sometimes used to distin ...

s, pellets, chippings,

fibres Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...

, slivers, any kind of

slurries A slurry is a mixture of denser solids suspended in liquid, usually water. The most common use of slurry is as a means of transporting solids or separating minerals, the liquid being a carrier that is pumped on a device such as a centrifugal pu ...

and aggressive products. Ball valves, piston valves or gate valves could fail when in contact with aggressive products, due to body seat or the gate/piston wearing out too quickly. Air-operated pinch valves work with less wear of the elastic rubber hose because the

kinetic energy In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acc ...

of the solids are absorbed through the high elasticity of the rubber that also helps to resist abrasion.

Material selection

The sleeve material is selected among suitable synthetic polymer based upon the corrosiveness and abrasiveness of the flow media. A key selection criterion is the operation temperature, which needs to be within the limit of the polymer. Several

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, an ...

qualities are available for pinch valves such as

natural rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and ...

, EPDM, nitrile, viton, neoprene and

butyl In organic chemistry, butyl is a four- carbon alkyl radical or substituent group with general chemical formula , derived from either of the two isomers (''n''-butane and isobutane) of butane. The isomer ''n''-butane can connect in two ways, gi ...

. Different housings and end covers/flange materials such as

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

, plastics and stainless steel are also available;

References

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