Butterfly check valve refers to a valve that automatically opens and closes the valve flap by relying on the flow of the medium itself to prevent the backflow of the medium, also known as check valve, one-way valve, reverse flow valve, and back pressure valve. The check valve is an automatic valve whose main function is to prevent the backflow of the medium, the reverse rotation of the pump and the driving motor, and the discharge of the container medium. Check valves may also be used on lines supplying auxiliary systems where pressure may rise above system pressure. Check valves can be mainly divided into swing check valves (rotating according to the center of gravity), lift check valves (moving along the axis), and butterfly check valves (rotating along the center).
Structural features of butterfly check valve:
Butterfly check valves include swing check valves and lift check valves. Swing check valves have a hinge mechanism and a door-like disc that rests freely on the sloping seat surface. In order to ensure that the valve disc can reach the proper position of the valve seat surface every time, the valve disc is designed in the hinge mechanism, so that the valve disc has enough swing space and makes the valve disc truly and comprehensively contact the valve seat. Discs can be made entirely of metal, or inlaid with leather, rubber, or synthetic overlays, depending on performance requirements. In the fully open condition of the swing check valve, the fluid pressure is almost unimpeded, so the pressure drop across the valve is relatively small. The disc of the lift check valve is seated on the sealing surface of the valve seat on the valve body. Except that the valve disc can rise and fall freely, the rest of the valve is like a globe valve. The fluid pressure lifts the valve disc from the sealing surface of the valve seat, and the backflow of the medium causes the valve disc to fall back to the valve seat and cut off the flow. According to the conditions of use, the disc can be of all-metal structure, or it can be in the form of rubber pads or rubber rings embedded on the disc holder. Like the globe valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than that of the swing check valve, and the flow of the swing check valve is limited rare.
Installation process of butterfly check valve:
1. The butterfly check valve can be installed horizontally (the arrow is parallel to the horizontal ground), or it can be installed vertically (the arrow is perpendicular to the horizontal ground). Generally, if the DN is greater than 400, try to install it in the horizontal direction.
2. Before installation, the pipeline should be cleaned, and the flash lamp should be fully inspected to ensure that it is not damaged before loading into the pipeline. When loading, pay attention to the direction of the arrow that is consistent with the running 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 the maintenance of the valve and other equipment.
4. When strengthening the flange connection bolts, attention should be paid to the symmetry, uniformity and firmness.