Pinch valve also known as a clamp valve, is an elastomeric tube or sleeve, which can be squeezed at its mid-section by some mechanical system until ultimately the tube walls are pinched or clamped together producing full closure of the flow path. In its simplest form, it consists merely of a length of elastomeric tube fitted with a pinch bar mechanism incorporating a closure stop to prevent over-pinching of the tube. Usually the molded rubber tube is housed in a metal body, which also incorporates the pinching mechanism. This can be a simple screw operated mechanism, where the pinch is applied only to one side of the tube, or a differential screw controlling two pinching mechanisms working in vertical opposition. The latter produces lower stress working of the tube.