chek valve HH44X-10/16 

is a check valve in which the disc, the movable part to block the flow, swings on a hinge or , either onto the seat to block reverse flow or off the seat to allow forward flow. The seat opening cross-section may be perpendicular to the centerline between the two ports or at an angle. Although swing check valves can come in various sizes, large check valves are often swing check valves.