Pinch Valve Operation
Operating pressures for controlled material vary depending on sleeve elastomer and valve size, and can range from a moderate vacuum (up to 26" Hg) to a maximum of 90 psi when controlling with air.
Required control pressure is normally 20 to 40 psi greater than the material pressure. Use of excessive actuation pressure (air or liquid) than that which results in complete valve closure will impact sleeve life. Use of actuation pressure above 90 psi is not recommended.
Airpinch pinch valves are normally open and require constant pressure for complete closure. Therefore, a loss of control pressure will allow the valve to open. In the event of sleeve failure, controlled material can enter the actuation system.
CAUTION: Airpinch pinch valves should not be used in applications where such conditions could cause system damage or failure. The designer must recognize that sleeve failure can occur at any time.
The actuation valve controlling the Airpinch must have free exhaust to allow the Airpinch to open. A solenoid, manual, or air-pilot operated 3-way control valve is required. A check valve cannot be used between the Airpinch and exhaust port of the controlling valve. Using a QEV can improve valve opening response time.
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