Fixed ball valve and floating ball valve sealing principle

Fixed ball valve is mainly used in high pressure large diameter ball valve. According to the different installation of the seat ring, the ball valve has a fixed front seal seat and ball seat sealing the valve seat two structures. Sealing ball seat sealing principle: The stem and the ball into a whole can be up and down in the sliding bearing or rolling bearing rotation, the seat ring is installed in the active sleeve, the sleeve in the body with 0 Ring seal. The seat ring is pre-compressed by a set of springs mounted in the sleeve. The inlet seat, when the ball valve is closed, depends on the diameter d at the inlet end and the diameter D of the sleeve that cooperates with the valve body. Of the circumference of the annular surface of the medium pressure limit the valve seat to the ball pressure, so as to play the role of import seal, the outlet end of the valve seat can not afford to seal. Reverse pressure, the role of the valve seat will change. Floating ball valve body has two seat ring, clamping a ball between them, the ball has a through hole, the diameter of the through hole equal to the pipe diameter, said full-diameter ball valve; the diameter of the through hole slightly smaller than the pipe Inside diameter, said reduced diameter ball valve. The ball body is free to rotate in the seat ring by means of a valve stem. When turned on, the ball hole is aligned with the pipe aperture to ensure that the working medium resistance of the pipe is minimized. When the valve stem rotates 1/4 turn, the ball hole is perpendicular to the valve passage, and the ball is tightly pressed against the valve seat sealing ring on the outlet end by the pre-tightening force and medium pressure applied to the two valve seat sealing rings to ensure that the valve Completely sealed. This ball valve is a one-sided forced seal. Floating ball valve should also focus on its seat material can withstand the load of the ball, because the ball in addition to its own weight but also to bear the full load of the working medium and pass to the seat. In addition, consider the large-diameter float valve in the operation requires a lot of force. In order to ensure the sealing and reliability of the floating ball valve work, the contact surface of the ball and the seat should have a high enough sealing pressure, but not more than the allowable specific pressure of the seat material. The seating of the valve seat in the groove should be tight, otherwise the medium will leak along the groove end face, even if the valve seat seals the ball very well. Spheres should have the correct geometry and low surface roughness values. Usually h6 or h7 precision ball manufacturing, the surface roughness value is not greater than R.0.4, in order to improve the ball surface hardness and wear resistance, the ball surface should be hardened. Sealing seat made of plastic, and should ensure close fit, shall not damage the sealing surface of the ball. At the same time, the material should be strong enough to withstand high seal pressures. Teflon is one of the most commonly used materials for making valve seats. Search Keyword: More Valve Technical Articles Valve Products Supply Information

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