Double disc wafer check valves are automatic valves that open and close the valve disc relying on the flow of the medium to prevent the medium from flowing back. They are also known as non-return valves, one-way valves, backflow valves, and back pressure valves. The main function of check valves is to prevent the medium from flowing back, prevent pumps and driving motors from reversing, and release the medium in containers. Check valves can also be used in auxiliary systems where the pressure may rise above the system pressure to provide supply on the pipeline. Check valves can mainly be classified into swing check valves (rotating around the center of gravity), lift check valves (moving along the axis), and double disc wafer check valves (rotating around the center).
Structural features of double disc wafer check valves:

Double-disc swing check valves include swing check valves and lift check valves. Swing check valves have a hinge mechanism and a disc that is free to swing against an inclined seat surface, similar to a door. To ensure that the disc reaches the correct position on the seat surface each time, the disc is designed with a hinge mechanism to provide sufficient swing space and ensure full contact with the seat. The disc can be made entirely of metal or have leather, rubber, or synthetic coverings embedded in it, depending on the performance requirements. When fully open, the fluid pressure is almost unobstructed in a swing check valve, resulting in a relatively small pressure drop across the valve. In a lift check valve, the disc sits on the sealing surface of the valve seat in the valve body. Except for the disc that can freely lift and lower, the rest of the valve is similar to a globe valve. Fluid pressure lifts the disc off the seat sealing surface, and backflow causes the disc to fall back onto the seat and stop the flow. Depending on the operating conditions, the disc can be all-metal or have rubber pads or rubber rings embedded in the disc frame. Like a globe valve, the fluid passage through a lift check valve is narrow, resulting in a larger pressure drop compared to a swing check valve. Also, the flow through a lift check valve is more restricted than that through a swing check valve.

Installation process of double-disc wafer check valve:
1. The double-disc wafer check valve can be installed horizontally (with the arrow parallel to the ground) or vertically (with the arrow perpendicular to the ground). Generally, for DN larger than 400, horizontal installation is preferred.
2. Before installation, the pipeline should be cleaned, and the valve should be thoroughly inspected to ensure it is undamaged before being installed into the pipeline. During installation, pay attention to ensure that the direction indicated by the arrow is consistent with the flow direction of the medium.
3. A filter should be installed at the inlet of the valve, and a butterfly valve or gate valve should be installed at the outlet to facilitate maintenance of this valve and other equipment.
4. When tightening the flange connection bolts, it is necessary to ensure that they are tightened symmetrically and evenly.