Free Directory, Your SEO Help Link Directory

The Union of Pinch Valves and Their Sleeves

Date Added: July 15, 2011 05:50:53 AM



The sleeve for pinch valves is composed of two flexible sleeves, one located inside the other; but it is the inner bladder sleeve that determines the route for the flow of a material through the valve. When the valve is open, the material flows under directed pressure between the inner and outer sleeves. Between the two bladder sleeves, a chamber is formed into which the material flow is directed.

To close the valve, pressure is applied to the exterior of the outer bladder sleeve of the pinch valve, causing the sleeve to collapse, thus closing the flow-through passage. A bladder for pinch valve provides an area of exit, relative to the flow of a material process between the inner and outer bladder sleeves. A reduction of the flow is possible between the bladder sleeves, or can be increased according to the determined pressure.

The control valve can be actuated by hydraulic action or electronically. For a hydraulically operated bladder for pinch valve, a cylinder with an expandable bladder inside is regarded as one of the earliest types of valves. This was connected to the discharge side of a pump used to expand the bladder, with a high-pressure line which also served in the pinching of a material flow and diversion. On the suction side of the pump is a low-pressure line, which deflated the bladder, thereby, allowing the flow to continue.

The sleeve for pinch valve is produced on mandrels, which are treated in a dispersion of natural rubber in water. As they are chemically treated with the purpose of attracting the rubber molecules, the mandrels build up a thickness of around 0.4-0.5 mm quickly. For the advanced composite laminates, cured bladders are usually between 0 .020" to 0.030" thick. Although the time element increases considerably over 0.060, if required, a thicker bladder for pinch valve can be supplied. Following the dipping process, the bladder is cured in an oven at 220° F. Shrinking of the material will occur after the curing process. Bladders are manually removed from the mandrels by stretching the open end and treating with compressed air, or a mechanical device.

It is usual for a sleeve for a pneumatic pinch valve to be utilized in a round tube which can be run through a bored hole in the mold. It is an act that is generally conducted on a split line of the mold and with seals made from O-rings on a line-drilled rod or with the lay-up mandrel itself. Due to advancements in technology, there is a formulation for natural rubber that is re-useable for many composite curing applications. At temperatures more than about 220°F, natural rubber progresses into a state of degradation. However, this action has been reduced by formulating the rubber for a shorter term of temperature resistance. Latex designed for high temperature resistance, will operate for an estimated 25-30 hours at 250°F; however, it will decline to around one hour at 350° F.

For more information on industrial pinch valves and rubber sleeves, please visit www.pinch-valve.com