Pinch valve
Pinch valves or hose pinch valves usually consist of a tubular, round or elliptical passage housing and a piece of elastomer hose inserted into it as a sleeve, which is sealed at both ends by a flange or a sleeve to the housing.
By inserting a piston, a bar or a tongue at the side of the hose section or by pressing in a control fluid or a gas from outside the hose section, the latter is squeezed. The hose piece reduces or closes the free passage for liquids, gases or mixtures of substances flowing through .
The space that forms between the elastomer hose section and the housing when the valve closes is called the control or functional space.
function
When compressed air , another neutral gas , a fluid or a solid body is fed into the valve housing, the elastomer hose piece becomes lip-shaped and blocks the flow of product. When the control / functional space of the valve housing is released by venting or draining, the pressure of the medium opens the elastomer hose section again until it is fully open.
Types
Valves operated by a fixed element are usually referred to as mechanical pinch valves . Magnetic hose pinch valves are controlled electrically.
Valves controlled by a liquid are called hydraulic hose pinch valves . Valves controlled with compressed air are called pneumatic pinch valves . In connection with electropneumatic proportional valves , pneumatic hose pinch valves can also be used for coarse regulation or metering of the product flow.
Areas of application
Hose pinch valves are mainly used to shut off abrasive, corrosive and fibrous products, the solid content of which would lead to rapid wear, clogging or blockage of conventional valves.
Hose pinch valves are used specifically to shut off and control material flows with solid components such as granular and crystalline media, powders , dusts , pellets , chips, sand , cement , gravel , textile fibers , coal and sludge tightly.
Depending on the intended application, elastomers such as natural rubber , EPDM , NBR , chloroprene rubber , Viton and silicone rubber are used in conjunction with different housing, flange and sleeve materials. Plastic , cast steel , aluminum or stainless steel can be used for the housing .
Typical applications:
- Bulk material technology ,
- Extraction systems ,
- Water jet cutting systems,
- Water treatment plants ,
- Dosing systems,
- Weighing systems, as a cuff
- Vacuum toilet system ,
- Powder coating systems ,
- Cement industry ,
- Silo filling units ,
- Mortar / plaster spray systems,
- Commercial vehicle technology ,
- Mash distribution during winemaking
advantages
The advantages of a pinch valve compared to other shut- off valves are:
- minimal frictional resistance and no tendency to clog due to free product flow without deflection of the material flow
- low weight and simple construction with few moving parts
- reliable seal
- easy automation.
Compared to ball valves, there are fewer pressure surges (kickbacks) when closing.
Depending on the medium and elastomer, the hose section has to be replaced more or less frequently.