Models: 105MDT, 109MDT, 113DT, 117DT Typical Service Designed for liquids and gases where flow reversal can cause surge and water hammer. Used extensively in pump suction and discharge Features Spring closes the disc before flow reversal, preventing surge and water hammer Mating surfaces of the disc and seat are hand lapped for best possible sealing. Disc is fully guided at top and bottom to insure alignment and sealing at any installation angle. Disc begins to open at .5psi. Disc opens 1/3" per inch of line size, greater than similar competitive products, for enhanced flow. Bodies are designed to accommodate 110% flow of equivalent pipe size.