A common problem with Pinch Valves is the rubber sleeve collapsing or deforming, causing the valve not to open fully. Depending on the abrasive quality of the application, this can cause excess wear on the sleeve.
95% of the time, this problem is created because the Pinch Valves are not being used correctly. However, it is a simple fault to fix and can usually be easily prevented.
– Media – Suspension of flour and water
– Pressure of Media – Positive pressure but very low
– Temperature of media – 55Deg C
– Pressure applied to close the Pinch Valve – 5 bar
– Pinch Valve opens/closes 4 times per day
– Pinch Valve is held in the normally closed position.
The differential pressure should be no more than 2.5 BAR. If the line pressure is for example 1 BAR then only 3.5 BAR maximum should be used to close the sleeves. 5 BAR pressure is holding these Pinch Valves shut all day, apart from the 4 times they are open and the line pressure of the product is not strong enough to push the sleeve back to the fully open position.
Reduce the control pressure to prevent the sleeve from deforming into the closed position. This will lengthen the lifetime of the sleeve. Also, if the Pinch Valve is not in use such as when the site is closed, leave the sleeve open if possible.
When using vacuum on a product passing through a Pinch Valve, the suction from the inside can pull the sleeve partially closed. The way to solve this problem is by piping the same vacuum pressure to the inlet of the Pinch Valve. This will then allow the vacuum to suck from the inside as well as the outside, equalising the pressure.
Sometimes, the Pinch Valve is operated by a solenoid valve. The vacuum can be piped to the exhaust point on the solenoid valve and the method above works in the same way.
We offer an accessory to help further with this problem. Our AKO-VAC System effectively pulls the sleeve open if required, or prevents the sleeve from closing under vacuum.
AKO Pinch Valve Sleeves have the potential to carry out approximately half a million cycles in their lifetime. Under the correct conditions as guided above, depending on your application, your sleeve could last even longer!
