Dual Plate Check:
The valve body is cylindrical in shape and the disk is in the form of two semicircular plates attached to a central hinge pin located in the body. The disk plates are acted upon by one or more torsion springs mounted on the hinge and these hold the plates against a flat seating in the body. The pressure of reverse flow on the plates causes the springs to deflect and allow the plates to move to an open position. Each plate may be acted upon by a spring or springs independently of the other plate, and on larger valves each plate may be independently supported. The incorporation of such features improves plate response when rapid changes of flow rates are experienced and reduces the severity of pressure surges.