Pinch valves, also known as bladder or soft seated valves, are simple to operate and suitable for a wide range of industries. They are made up of 3 main components: a housing, end connections and the rubber sleeve which fits inside.
The rubber sleeve is the most crucial component in pinch valve and is available in different grades of rubber. This ensures that various areas of application, operating temperatures and lasting properties are possible.
This rubber sleeve is manufactured using a number of different procedures, including manual winding and injection moulding. The type of manufacturing procedure used determines the closing and opening characteristics as well as the cycle frequency involved in pinch valve operations.
When a pressure is applied to the pinch valve, the elastomeric rubber sleeve is pushed down. This pinching action creates a seal around the valve, and prevents any fluid from flowing through it.
In conventional valves, such as globe, diaphragm, butterfly, gate or ball valves, particles can get trapped in the seal and clog the valve. In contrast, the rubber sleeve in a pinch valve forms a tight shut off around any solids, eliminating any entrapment that can occur if using a globe, diaphragm, butterfly or gate valve.
Once the force is released, the sleeve’s elastic rebounding property, in conjunction with the upstream flow, fully opens the valve. This frees the media from clogging, and allows it to flow freely.
The sleeve is the only part of the valve that comes in contact with the media, so it must be lightweight and be compatible with the product it is meant to handle. It is a good idea to select a rubber that has a high abrasion resistance and is food grade.
The sleeve can be replaced at any time, reducing maintenance costs and wear. This is particularly beneficial in a pinch valve that is used to control media with an entrained solids content such as granules, powders, pellets, chippings, fibres or slivers. This is because the sleeve’s drop-tight shutoff prevents any entrapment of the granules or other solids by the seat or in crevices that would happen with a globe, diaphragm, gate or ball valve.