Small diameter hard sealing ball valve product knowledge

Small diameter hard sealing ball valve product knowledge

1 Overview

Hard-sealed ball valves have been widely used in petroleum, chemical, metallurgy  urban central heating industries. However, the ball valve made of PTFE polymer material for the sealing pair cannot be used in the conditions  the temperature is higher than 280 ℃  the conveying medium is in the form of tiny particles. The hard-sealed ball valve with metal material as the sealing pair will have various situations due to different structures when the ball is rotated. Such as the metal elastic valve seat sealing structure, since there is no gap between the elastic valve seat  the ball, the friction force is very large. The metal floating valve seat sealing structure is  easy to seal between the floating valve seat  the valve body. The combined ball-opening sealing structure, due to the many parts  complex structure, increases the processing difficulty  manufacturing cost, especially for small-diameter hard-sealed ball valves, this structure is obviously  applicable. After repeated analysis  testing,  with the aid of CAD-aided design, the Q47H cam eccentric single-seat fixed hard-sealing ball valve was successfully developed.

2 How it works

The center line of the ball of the cam eccentric single valve seat is offset a  b relative to the center line of the valve body,  the sealing surface of the valve seat is eccentric b. When the valve stem rotates 90° clockwise around the O point, the sphere also rotates 90°,  closely matches the sealing surface of the valve seat. When the torque is high, the valve will achieve a reliable seal. Since the valve seal adopts a cam-type eccentric structure, when the valve is opened, the ball quickly leaves the sealing surface of the valve seat. When the valve is closed, the ball quickly engages with the seat sealing surface. So as to achieve the purpose of small opening torque  tight closing.

3 Structural features

Small-diameter valves have a narrow body cavity,  the usual structural design is no longer applicable. Therefore, the end of the valve stem is machined into a flat shape with a short axis. There are flat grooves  holes on the upper  lower sides of the sphere. The holes are used to connect the upper  lower valve stems to fix the sphere, limit the degree of freedom of the sphere,  balance the body cavity  pipeline. The effect of pressure between media. The flat groove cooperates with the valve stem  transmits the torque  the handle.

4 Manufacturing  processing

The coaxiality of the two holes of the sphere  the eccentric dimensional tolerance of the center line of the sphere relative to the center line of the valve body are relatively strict,  generally require boring machine  CNC machine tool processing. Before assembly, the sealing surface of the valve seat  the surface of the sphere should be ground together, then the sphere should be placed in the closed position, the left valve body should be installed, the gasket should be adjusted, the screws should be tightened,  the static pressure should  leak, then the valve can be sealed under the sealing test. .

5 Conclusion

The small-diameter hard-sealed ball valve complies with the existing domestic  international standards for the structure length, connection form  connection size of the ball valve. The valve has been used in metallurgy, textile  petroleum industries with good results.