What is the difference between H76 check valve H77 ?
The H76x check valve is wafer type double disc rotating structure, and the H77x is wafertype single disc butterfly structure.
The wafer check valve is also called counter flow valve, back pressure valve, one way valve. This type of valve is automatically opened and closed by the force generated by the flow of the medium itself in the pipeline and belongs to an automatic valve.
The function of this type of valve is to allow only the medium to flow in one direction and to prevent the flow in the opposite direction. Usually this valve works automatically, and the disc opens under the action of fluid pressure in one direction; when the fluid flows in the opposite direction, the fluid pressure and disc self-reclosing disc act on the seat, thus cutting off the flow.
The stainless steel wafer type check valve belongs to this type of valve, which includes rotary check valve and lift check valve. The swing check valve has a hinge mechanism and a door-like disc that rests freely on the tilted seat surface. To ensure that the disc reaches the proper position of the seat surface each time, the disc is designed in a hinge mechanism so that the disc has sufficient swing space and allows the disc to truly, fully contact the seat.The disc can be made entirely of metal, or it can be inlaid with leather, rubber, or synthetic coverage, depending on the performance requirements. When the rotating check valve is completely open, the fluid pressure is almost unhindered, so the pressure drop through the valve is relatively small. The disc seat of the lift check valve is located on the seat sealing surface on the valve body. Except that the disc is free to rise and fall, the rest of the valve, like the globe valve, is lifted from the seat seal by fluid pressure, and the medium reflux causes the disc to fall back to the seat and cut off the flow.