Ball valve seat structure principle

1. Overview The main function of the ball valve is to cut off or connect the fluid passage in the pipeline. The working principle of the ball valve is to apply a certain torque to the ball at the upper end of the valve stem through a drive device to rotate it by 90° to complete the action of opening or closing the valve. The sealing principle of the ball valve seat varies according to its structure. The commonly used valve seat structure of Hongfeng Valve can be divided into two categories: fixed seat floating ball and floating seat fixed ball. When the fixed ball seat floats, the ball moves under fluid pressure in the direction of fluid flow, making it more tightly in contact with the valve seat, which means that the specific pressure on the sealing surface increases to form a single face. Sealing, at the same time, the specific pressure on the sealing surface of the front valve seat is reduced accordingly, and sealing is often not guaranteed. When the valve seat floating ball is fixed, the fluid pressure can not make the ball displacement, but the valve seat is pressed against the ball by the spring or the fluid thrust to establish the sealing specific pressure.

2, structure 2.1, soft seal valve seat (1) Ordinary ordinary valve seat is characterized by preload or fluid pressure under the pressure of the seat and ball compression, and make the seat material elastic plastic deformation to achieve sealing, The sealing effect depends on the ability of the valve seat to compensate for roundness and surface irregularities of the ball under fluid pressure or preload. Therefore, there must be a sufficiently large sealing specific pressure between the valve seat and the ball.

(2) Elastic elastic valve seats are elastically deformed by means of elastic elements such as metal spring frames and springs under pre-tightening force or fluid pressure to compensate for the effect of changes in external conditions such as temperature difference, pressure, and wear on the sealing performance of the ball. .

4. Conclusion Valve seats and seals are key components of ball valves. Hongfeng Valve believes that the seal ring should have excellent stability, a small coefficient of friction, not easy to age, and good sealing performance. The valve seat should have a certain strength and rigidity, the gap is moderate, and it is not easy to deform when pressed. Metal seal seats should meet the high temperature, high pressure, strong corrosion, ultra-low temperature, zero leakage, long life, fire safety and pressure wear and other functions.