Pinch valves are flex-body valves consisting of a flexible tube that is pinched either mechanically, as in the valves shown in Figure 3-88 through Figure 3-90, or by the application of a fluid pressure to the outside of the valve body, as in the valves shown in Figure 3-91 and Figure 3-92.

One of the principal advantages of this design concept is that the flow passage is straight without crevices and moving parts. The soft valve body also has the ability to seal around trapped solids. Pinch valves are therefore suitable for handling slurries and solids that would clog in obstructed flow passages, and for the sanitary handling of foodstuffs and pharmaceuticals. Depending on the construction material used for the valve body, pinch valves will also handle severely abrasive fluids and most corrosive fluids.

Open and Enclosed Pinch Valves

Mechanically pinched valves may be of the open type, as in the valve shown in Figure 3-88, or of the enclosed type, as in the valves shown in Figure 3-89 and Figure 3-90.

Figure 3-88: Pinch Valve, Open Construction. ( Courtesy of Flexible Valve Corporation.)

Figure 3-89: Pinch Valve, Enclosed Construction, and Valve Body 50% Prepinched for Sensitive Flow Control. Drain Plug May Be Removed for Vacuum Connection When Valve Is Used on Vacuum Service. ( Courtesy of RKL Controls, Inc.)

Figure 3-90: Pinch Valve, Enclosed Construction, PTFE Valve Body Fitted with Tear Drops. ( Courtesy of Resistoflex Corporation.)

The open construction is used if it...