How Does an Air-Operated Pinch Valve Work?
In an air-operated pinch valve, compressed air — or a neutral gas — is fed into the space between the sleeve and the housing. The pressure applied to the outside of the sleeve pinches it shut from all sides simultaneously. The closure is complete and reliable, even when the medium contains solid particles.
In the open position, the valve provides a full nominal bore with no dead zones. There are no moving mechanical parts in contact with the medium — only the sleeve. When compressed air is lost, the sleeve returns to its open position through its own elasticity (normally open, N/O).
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For Which Media and Applications Is This Type Suitable?
The air-operated pinch valve is particularly suitable for media that would damage or block conventional valves:
Abrasive media: sand, cement, slurry, ore — the sleeve wears, not the housingFibrous media: pulp, fibre suspensions, wastewater with solid particlesViscous media: pastes, suspensions, high-viscosity productsPowders and granules: plastic pellets, chemical powders, food ingredients
Application sectors include mining, water treatment, chemical industry, food and beverage, and concrete and cement. The combination of full bore flow and straightforward sleeve replacement makes this type suitable for continuous operation.
Which Versions Are Available?
AKO-Armaturen supplies air-operated pinch valves in an extensive range of configurations:
Nominal diameters: DN10 to DN300Housing material: aluminium (VF series), stainless steel (VMC series), POM plastic (VMP series)Connection types: flange, internal thread, clamp, weld-on end — depending on the seriesSleeve materials: 18 elastomers including NR, EPDM, NBR, FPM and siliconeCertification: CE compliant, PED and Machinery Directive; sleeves available to FDA and EC 1935 for food applications
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What Are the Advantages of Direct Air Actuation?
Direct air actuation differs from cylinder actuation on several technical points:
No mechanical wear on the actuator — no pistons, rods or bearings that wear outFast switching times — the sleeve responds immediately to pressure changesSimple installation — only a compressed air connection required, no additional actuatorLower purchase cost — simpler construction means a lower price than cylinder-actuated versions40% lower energy consumption — the elliptical housing of the VMC and VF series significantly reduces the closing pressure required
When Should You Choose an Air-Operated Instead of a Cylinder-Actuated Pinch Valve?
Criterion
Air-operated (direct)
Cylinder-actuated
Operating principle
Compressed air directly on sleeve
Pneumatic cylinder pinches sleeve shut mechanically
Closing force
Dependent on operating pressure
+ Higher — independent of medium pressure
Suitable for high back pressure
- Limited
+ Yes
Construction
+ Simple, few components
More complex
Switching time
+ Fast
Slightly slower
Purchase cost
+ Lower
Higher
Application
Standard industrial processes
High pressure, tough media, increased closing force required
Not sure which type is right for you? Provide your process pressure, medium type and required closing force — we will advise the correct version. See also the cylinder-actuated pinch valve for a direct comparison.
Wear Parts and Maintenance
The sleeve is the only wear part of an air-operated pinch valve. AKO-Armaturen supplies sleeves in 18 elastomer grades, selected for medium, temperature and wear load. The sleeve is straightforward to replace. Depending on the model, this can be done without removing the full housing from the pipeline. Ebora supplies the wear parts and replacement sleeves for the standard AKO-Armaturen series.
Frequently Asked Questions
What compressed air pressure is needed to close an air-operated pinch valve?
The required closing pressure depends on the nominal diameter and the medium pressure in the pipeline. As a general rule, the operating pressure should be at least 1 bar higher than the medium pressure. For exact pressure specifications per series and DN, please refer to the technical datasheet or contact our team.
Can an air-operated pinch valve be supplied in a normally closed version?
The standard version is normally open (N/O): when compressed air is lost, the sleeve returns to the open position through its own elasticity. Festo also supplies a normally closed (N/C) version that closes automatically when compressed air supply is lost. Select this version when your process requires a safe shut-off in the event of an energy failure.
Is an air-operated pinch valve suitable for food or pharmaceutical applications?
Yes, provided it is fitted with the correct sleeve. AKO-Armaturen supplies sleeves compliant with FDA and EC 1935 for food applications. For aseptic or EHEDG-certified applications, the VMCE series is available with hygienic connections in stainless steel.
Select the right air-operated pinch valve based on medium, diameter and operating pressure, or request a quote directly via our contact page . See also our overview of all pinch valves for a comparison of all actuation types.
