AKO is your source for low maintenance pinch valves ideally suited for a wide variety of applications and industries. Features of AKO pinch valves include:

• Full port, straight through flow
• Tolerates high percentage of solids
• Negligible head loss
• Full shut-off, even with suspended solids in the stream

AKO pinch valves are the most practical solution for all kinds of flow control applications including abrasive, corrosive and fibrous products, granules, powders and slurries. Pinch valves are made up of only a few parts, with the flexible sleeve being the most important item. Enclosed and surrounded by a housing, the valve sleeve is firmly held in place between the two ends of the valve housing.  By introducing compressed air or a suitable liquid between the valve body and the sleeve, the valve can be fully closed or "pinched off". When the external pressure on the sleeve is released the sleeve will again spring back to its original fully open position.

Basic Operating Principle of a Pinch Valve	Sleeves available in over a dozen elastomers	Pinch Valves are used for liquids, slurries and dry materials

What to look for when specifying Pinch Valves

1. Starting with the sleeve, the choice of material is most important and compatibility of sleeve material and product is the basis for long and trouble free valve operation. One of the key features of a good sleeve is maintaining straight through, full bore flow when open. If the sleeve material is not sufficiently flexible and develops a "memory" (will no longer open fully when closing pressure is released) the walls of the sleeve protrude into the product stream generating increased pressure drop, causing unnecessary turbulence and increased abrasion of the sleeve walls when slurries or abrasive granules are in the product stream. As a result the sleeves will wear prematurely resulting in an increase in downtime.
    
2. Pinch valves should be designed so that they fit easily between flanges of the connecting piping without having to add extra space needed for compression of flanged sleeves when the valve has to be removed for service. The valve design shall be such that the sleeve is completely contained between the metal flanges of the valve housing, making removal and insertion into the pipeline possible without having to loosen adjacent pipe supports for clearance. This also allows for maintaining the proper torque for flange connections without being dependent on the resiliency of the sleeve’s rubber flange to achieve proper sealing.
    
3. When contamination of the product is a factor in the application, all wetted surfaces of the pinch valve must be considered. Therefore, where sleeves have a simple cylindrical shape and no flanges on either end, the end flanges of the valve housing should be available in the appropriate material or with a flange liner for compatibility.
    
4. The pinch valve housing, especially for larger diameter valves, should be available in a light material, such as aluminum, to make it easier to handle the valve. Since the housing normally does not come in contact with the product it is usually not necessary that the housing material be compatible with the product as long as the surfaces of the housing have a suitable protective coating against the surrounding elements.
   
   The volume of the annular space between the housing walls and the sleeve determines the volume of compressed air or liquid required to close the valve and the smaller this volume is, the less fluid exchange is necessary and less energy is expended during cycling. In addition, smaller housings save on weight and make the valves easier to handle, saving transportation and installation costs. (Mechanically actuated pinch valves utilize a wedge to close the valve and different design criteria apply).
    
5. Successful selection of a pinch valve for a specific application depends upon selecting the optimum sleeve material that will provide maximum compatibility with the product to be handled. While the housing material for each valve can be the same, the sleeve material and construction will determine, to a great extent, how successful the application will be. Factors such as pressure, product temperature and chemical properties may allow a natural abrasion resistant rubber sleeve while higher temperatures may require special elastomers such as silicone. Specific industries, such as Food/Beverage and Pharmaceutical, may require food grade elastomers.
    
6. Pinch valves have only one moving part to be concerned with - the sleeve.  It can be either full open or closed or used as a flow control device, somewhere in-between.  Fully open and fully closed requires only normally closed or normally open solenoid control valves. However, pinch valves in series (with mechanical or pneumatic control), vacuum applications, or when fail-safe installations are required control schemes become more complicated and may require special considerations.