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.

AKOVAC-Perfect

The vacuum units of the AKOVAC-Perfect series allow a targeted setting of pressures on the control unit, once for the control pressure in order to close the pinch valve and once for the supply pressure in order to regulate the vacuum level.

The lower operating pressures required for use with a vacuum (1-2 bar) in order to close the pinch valve, and, if applicable, the slightly higher operating pressures used in order to achieve the ideal vacuum level needed to compensate for the medium-side vacuum can therefore be adjusted separately from one another.

In addition, the AKOVAC-Perfect units have a quick exhaust function and display various system pressures (supply pressure, closing pressure and pressure in the air operated pinch valve (-1 to +5 bar).

In contrast with the AKOVAC-Basic unit, the vacuum pump in the AKOVAC-Perfect version can be switched off and only runs when needed, saving compressed air and energy. The vacuum in the system is maintained after switching off the vacuum pump. If the vacuum level falls below the predefined level, this problem can be detected by an optional digital pressure switch. The vacuum pump is switched on again via the customer's control system.

AKOVAC-Basic

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.

AKOVAC-Central

AKOVAC-Central acts (in contrast to Basic and Perfect) as a central controled vacuum-unit. It is able to supply several decentralised control units (AKOVAC-CentralUnits) at various pinch valve with vacuum.
With AKOVAC-Central and the AKOVAC-CentralUnits, you are able to supply several pinch valves with vacuum using just one vacuum pump. This saves air, energy and costs.
The centralised supply via a vacuum pump makes sense wherever several pinch valves have approximately the same operating parameters and a vacuum supply is necessary or advantageous for operation.

If the pinch valves used have different requirements or operating parameters, AKOVAC-Basic or AKOVAC-Perfect are recommended.

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.

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