Control Pinch Valves
A Control Pinch Valve is a full bore or fully ported type of control valve which uses a pinching effect by pressurized air to obstruct the flow. Air operated Pinch Valves are very easily constructed. They generally only consist of an extremely elasticized reinforced rubber hose, a type of housing, and two socket end covers or flanges. The rubber hoses of the air operated Pinch Valves are usually press-fitted and centred into the housing ends by the socket end covers or flanges.
Applications
Fluids
Pinch valves used for fluids usually employ a device that directly contacts process tubing. Forcing the tubing together will create a seal that is equivalent to the tubing's permeability.
Solids
The most important benefits of using air operated Pinch Valves are their complete and true full bore, and the 100% tight shut off – even on solids such as granule, powders, pellets, chippings, fibres, slivers, any kind of slurries and many more aggressive products.
Examples
Air operated Pinch Valves are used in:
- Metering systems
- Weighing systems
- Powder coating systems
- Vacuum toilet systems
- Vacuum conveying systems
- Vacuum and compressed air control units
Particulates
Major components of a pinch valve consists of body and a sleeve. The sleeve will contain the flow media and isolate it from the environment hence reducing contamination to the environment. Generally used for slurries or processes with entrained solids, because the flexible rubber sleeve allows the valve to close droptight around solids—solids that would typically be trapped by the seat or stuck in crevices in globe, diaphragm, butterfly, gate, or ball valves. The sleeve material can be selected upon the corrosiveness and abrasiveness of the flow media, a suitable synthetic polymer can be chosen. A pinch valve may be the best type of valve for flow control application if the operation temperature is within the limit of the polymer.
Function
The air operated Pinch Valve works without any additional actuator; all it needs to close or operate is 30 psi air or 2-6 bar supply into the Pinch Valve body. As soon as the air supply becomes interrupted and the volume of air exhausts, the elastic rubber hose starts to open due to its great impact resilience.
Advantages
Usually conventional valves such as Ball Valves, Butterfly Valves, Piston Valves or Gate Valves tend to fail when in process with the above mentioned aggressive products. The reason is that the valve body seat or the gate/piston of the valves wears out too quickly and the valve can no longer shut off tightly, whereas air operated Pinch Valves work without almost any wear of the elastic rubber hose because the kinetic energy of the solids are absorbed through the extremely high elasticity of the rubber. The rubber mixture is also anti abrasive.
Used Materials
Sleeve
Therefore using Air Operated Pinch Valves in aggressive product processes saves a lot down time, and guarantees a free flow through the valve, avoiding any blockages. Several rubber qualities are available for Air Operated Pinch Valves such as
- Natural rubber
- EPDM
- Nitrile
- Viton
- Neoprene
- Butyl
Housing
Different housings and end covers/flange materials such as:
- Aluminium
- Plastics
- Stainless steel
Industries
Air operated Pinch Valves are being commonly used in a wide range of many different industries such as:
- Bulk Solids handling,
- Cement industry
- Waste water industry
- Chemical industry
- Food industry
- Beverage industry
- Ceramic industry
- Glass industry
- Plastic industry
Maintenance
Quick and simple replacement of all sleeve types of the air operated Pinch Valves with the assistance of detailed fitting instructions for them is reflected in the very low maintenance costs.
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