The lifetime of a Pinch Valve Sleeve is a very hard question to answer since every application is different. Some sleeves can perform up to 500,000 cycles over a period of 3+ years and some need replacing after 6 months after fewer cycles.
If a pinch valve is held in the normally open position and only closed when required then the internal rubber sleeve will last longer.
Here we look at a Pharmaceutical application as an example;
- Milled product is fed through the valve from a sifter into a pack-off system.
- The system throughput is 10kg/h and each drum holds 25kg so will take 2.5hrs to fill, during which time the valve will be open.
- Once the drum is filled the valve will be closed for the time it takes the operator to change the drum over which might be around 10 minutes.
- With the new drum in place the valve is opened, and the process repeated until a complete batch of around 150kg is processed and filled into drums.
- If we assume 8 hours per shift then it would take 2 shifts to process a complete batch during which time the valve will be mainly open.
- There then may be a time period where the valve is closed and the system not in use. It is likely that after either each batch or a number of batches the system is then cleaned with a detergent wash from above using a spray lance so pressure will not be too great. In rare circumstances where the product is sticking, methanol or acetone wipes may be used.
Pharmaceutical non abrasive powder at gravity pressure should be no problem at all and hardly any wear should be seen. As it is a gravity application, then closing the Valve at 2.5 BAR would be recommended. The cleaning process may deteriorate the Sleeve over time as the temperature and pressure would be higher.
We would recommend a yearly maintenance procedure to put into place. Once the Valve is installed then over time, it will determine learn how long the Sleeve is going to last and more or less frequent maintenance schedule can be planned at the time.
Scheduling a Maintenance Plan
The Valve will be mainly open, which is good for the sleeve lifetime.