Vacuum conveying with AKO Pinch Valves
If an air operated AKO pinch valve is put under pressure by vacuum > -0.1bar in terms of the medium used (in the pipeline), the valve's sleeve will be deformed by the vacuum. This will have a negative effect on the product's flow rate and the life time of the AKO pinch valve sleeve.
Recommendation for pinch valves in vacuum applications
If a vacuum suction is applied at a process vacuum of >100mbar, this vacuum is always to be compensated for in the air operated pinch valve.
The easiest way to compensate is by means of pure process vacuum which is activated in the bleed side of the solenoid valve via a bypass.
If there is no pure process vacuum available, or the vacuum source is too far away from the pinch valves, we alternatively recommend using our AKOVAC control elements.
The pinch valve sleeve can be opened or kept open by means of the AKOVAC's control unit. A vacuum mode of up to -0.8bar can be generated in the feed pipe (pipeline) in terms of the medium.
The AKOVAC Comfort model allows for the specific setting of separate pressures on the control unit for the control pressure, for closing the pinch valve and the control pressure which regulates the level of vacuum.
Therefore, the lower operating pressures required for use with vacuum (1-2 bar) for closing the pinch valve, and, if applicable, the slightly higher operating pressures used to achieve the ideal level of vacuum to compensate the medium's vacuum can be adjusted separately to one another.
The AKOVAC Basic model only allows one control pressure which regulates the needed closing pressure of the air operated pinch valve and at the same time the level of vacuum.
Control of Air pinch valves
We would also like to point out that the air operated pinch valves are to be controlled with a differential pressure of 2 - 3 bar. Therefore, it is advisable in the case of pure vacuum application (suction) with no overpressure, to reduce/ set the control/closing pressure of the air operated pinch valves to an ideal niveau of 2-3 bar by means of a pressure-reducing valve.
This measure will have a positive effect on the service life of the elastomer pinch valve sleeve.
For further details, please browse the corresponding accessory pages for our products.