This revision explains the flexible-sleeve closure and checks pneumatic control pressure using the manufacturer-supported line-pressure-plus-nameplate-differential relationship.
Pneumatic Pinch-Valve Pressure Check
Enter line pressure, the required differential printed for the selected valve and the available control pressure. This arithmetic check does not replace the valve nameplate, data sheet or operating instructions.
Equation Used
- All three entries use the same gauge-pressure reference and psi unit.
- The entered differential is taken from the selected valve's current nameplate or documentation.
- Available control pressure is measured at the valve under the relevant operating condition.
- The animation is an illustrative open-to-pinched sequence and is not a pressure-deformation model.
- Pressure losses, regulator droop, transients, sleeve material, temperature, fatigue, flow, sizing and safety margins are excluded.
Replaces a universal pressure multiplier with the manufacturer-supported line pressure plus valve-specific nameplate differential check.
Control pressure collapses a flexible sleeve
An air-operated pinch valve contains an elastomer sleeve inside a housing. Applying the specified control medium to the space around the sleeve collapses the sleeve and shuts the flow path; exhausting that control pressure allows the sleeve to reopen according to the valve design and process conditions.
The animated shape is illustrative. It does not predict deformation from pressure.
Use depends on the exact valve and sleeve
Manufacturer documentation covers pinch valves for liquids, gases, mixtures and difficult particulate or viscous media, but pressure, temperature, material compatibility and installation limits are product-specific. Select the sleeve and valve from the current manufacturer data rather than from a generic application list.
Use the specified differential, not a universal factor
AKO's operating manual gives an example of 3.0 bar operating pressure plus a 2.5 bar valve differential, producing 5.5 bar optimum control pressure. MOLLET likewise specifies control pressure as process pressure plus 2.5 bar for the cited QV sizes.
The former 1.2-to-2.5 multiplier and universal 1.5-to-2.0 recommendation are replaced because manufacturer differentials vary by valve and must be read from the applicable nameplate or product documentation.
A declared pressure-check example
At 60 psi line pressure with a declared 30 psi required differential, the arithmetic requirement is 90 psi control pressure. If 100 psi is available at the valve, the declared margin is 10 psi. This does not authorize exceeding any nameplate limit.
Pressure arithmetic is not valve sizing
The worksheet does not select a valve, sleeve material, regulator, relief device or compressor. It excludes flow capacity, pressure loss, temperature, chemical compatibility, vacuum service, transient pressure and sleeve fatigue.
Cla-Val cautions that excessive supply pressure can shorten sleeve life. Use the minimum pressure specified for reliable closure and comply with the exact valve's maximum operating and control pressures.
Pneumatic pinch-valve questions
Can I multiply line pressure by 1.5 for every pinch valve?
No. Use the required differential specified for the exact valve.
Does a positive worksheet margin prove safe operation?
No. Nameplate maxima, pressure regulation, transients, temperature and the complete manufacturer instructions still apply.
Does the animation predict sleeve deformation?
No.
Pneumatic pinch-valve references
- AKO, Operating Manual for Air Operated Pinch Valves: operating pressure plus the nameplate differential gives optimum control pressure; pressure limiting and nameplate limits are required.
- MOLLET QV operating instructions: control pressure specified as 2.5 bar above process pressure for the documented sizes.
- Cla-Val PV30 user manual: use minimum specified supply pressure and avoid excess differential that shortens sleeve life.
- Red Valve Series 75/70 manual: two pinch bars close a resilient sleeve on the centerline for the documented manual designs.
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