The utility model provides a slow-closing wafer check valve, which includes a valve body, a valve disc, a valve shaft, and a torsion spring sleeved on the valve shaft. The valve body is provided with a medium channel for medium circulation in the axial direction, which includes an inlet end and an outlet end. The valve disc, valve shaft, and torsion spring are symmetrically arranged in two groups relative to the center of the valve body. The utility model further includes a damping device located at the inlet end, which includes a cylinder inserted on the valve body, a piston rod located inside the cylinder, a spring, and a cover connected to the outer end of the cylinder. The cylinder is provided with a first cavity and a second cavity that are connected and communicated. The cross-section of the second cavity is square, and its cross-sectional area is larger than that of the first cavity. One end of the piston rod located inside the medium channel is provided with a movable block. The utility model has low noise and technical characteristics of quick opening, slow closing, and water hammer elimination, enabling light-load pump start-up and preventing the generation of water hammer during pump shutdown.

1. A slow-closing wafer check valve, comprising a valve body, a valve disc, a valve shaft, and a torsion spring sleeved on the valve shaft. The valve body is provided with a medium passage for medium circulation in the axial direction, and the medium passage includes an inlet end and an outlet end. The valve disc, valve shaft, and torsion spring are symmetrically arranged in two groups relative to the center of the valve body. The valve also comprises a damping device located at the inlet end. The damping device includes a cylinder inserted on the valve body, a piston rod located inside the cylinder, a spring, and a cover connected to the outer end of the cylinder. The cylinder is provided with a first cavity and a second cavity that are connected and communicated. The cross-section of the second cavity is square, and the cross-sectional area of the second cavity is larger than that of the first cavity. One end of the piston rod is located inside the second cavity, and the other end penetrates through the first cavity and is located inside the medium passage. The end of the piston rod located inside the medium passage is provided with a movable block, and the end of the piston rod located inside the second cavity is provided with an external thread. The second cavity is provided with a limit plate that is adapted to and threadedly connected with the piston rod. The spring is sleeved on the piston rod, with one end abutting against the limit plate and the other end abutting against the inner wall of the second cavity. The side of the valve disc facing the piston rod is provided with a driving block that cooperates with the movable block. During the closing process of the valve disc, the side of the driving block facing the center of the valve body cooperates with the movable block to achieve displacement of the piston rod relative to the cylinder towards the center of the valve body. The damping device is symmetrically arranged in two groups relative to the center of the valve body.

2. A slow-closing wafer check valve according to claim 1, characterized in that a square hole is axially provided at the end of the piston rod located in the second cavity, an adjuster is inserted at a position on the cover corresponding to the square hole, a driving rod adapted to the square hole is provided at the end of the adjuster, and the adjuster is rotatable relative to the cover.

3. A slow-closing wafer check valve according to claim 2, characterized in that a limit slot is provided at the connection between the cover and the regulator, and a limit mechanism is arranged inside the limit slot. The limit mechanism comprises a ball, a tower spring connected to the ball, and a positioning column for fixing the tower spring. At least four engaging slots adapted to the ball are provided circumferentially at the connection between the regulator and the cover.

4. A slow-closing wafer check valve according to claim 3, characterized in that the top edge of the engaging groove is provided with a rounded corner.

5. A slow-closing wafer check valve according to claim 1, characterized in that the valve body is provided with a stepped groove adapted to the cylinder body.

6. A slow-closing wafer check valve according to claim 5, characterized in that a sealing ring is sleeved at the connection between the cylinder and the valve body.

7. A slow-closing wafer check valve according to claim 1, characterized in that the valve disc is provided with a build-up welding layer that is sealed with the valve body. 8. A slow-closing wafer check valve according to claim 7, characterized in that one side of the build-up welding layer is provided with vulcanized rubber that is sealed with the valve body.