Ball valve seat structure principle
1, the main function of the ball valve is to cut off or connect the fluid channel in the pipeline. The principle of the ball valve is driven by the device at the upper end of the valve stem to apply a certain torque to the ball, so that the rotation angle is 90 degrees, the opening or closing the valve action was completed.
The valve seat sealing principle according to the structure of the valve seat structure varies, Adamant valves used fixed and floating seat fixed seat floating sphere. When the valve seat is fixed to floating ball, the ball body displacement in the direction of fluid flow under pressure, the valve seat and valve sealing it after closer contact, in which the sealing pressure increases on the surface, to form a single seal, at the same time, in front of the valve seat sealing surface than the pressure should be reduced, often do not guarantee seal. When the valve seat floating ball is fixed, the fluid pressure can not make the ball displacement, but the seat by means of a spring or fluid pressure to push the ball, the establishment of sealing pressure.
2.1, soft sealing seat
Ordinary seat is characterized by the pretightening force or fluid pressure under the valve seat and ball pressing, and the valve seat material elastic-plastic deformation to seal, the sealing effect depends on the valve seat in fluid pressure or under the effect of preload compensation of ball roundness and surface micro roughness ability. Therefore, the valve seat and the ball must be large enough to seal the pressure.
The elastic seat with the help of elastic components, such as metal spring frame and spring, elastic deformation in the pretightening force or fluid pressure, affect the sealing performance of the ball to compensate for variations in temperature, pressure and wear conditions.
Valve seat and seal ring is the key component of sanitary ball valve. Adamant valve that the sealing ring should have excellent stability, friction coefficient is small, not easy to aging, good sealing performance. Valve seat should have a certain strength and stiffness, the gap is moderate, not easy to deformation under pressure. Metal sealing valve seat should meet the functions such as high temperature, high pressure, strong corrosion, ultra low temperature, zero leakage, long life, fire safety and pressure resistance.