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How American Standard Stainless Steel Ball Valves Open and Close
发布日期:2018/9/19 9:39:00 点击数:106新闻来源:
American standard stainless steel ball valves are divided according to structure:
   1. Floating ball valve: The ball of the ball valve is floating. Under the action of the medium pressure, the ball can produce a certain displacement and press on the sealing surface at the outlet end to ensure the sealing of the outlet end. The floating ball valve has a simple structure and good sealing performance, but the load of the ball subjected to the working medium is all transmitted to the outlet sealing ring, so it is necessary to consider whether the sealing ring material can withstand the working load of the spherical medium. This structure is widely used in medium and low pressure ball valves.
   Second, fixed ball valve: The ball of the ball valve is fixed, does not move after being pressed. The fixed ball valve has a floating valve seat. After the medium pressure, the valve seat moves, so that the sealing ring is pressed against the ball to ensure the seal. Usually mounted on the upper and lower shafts of the ball, the operating torque is small, suitable for high pressure and large diameter valves. In order to reduce the operating torque of the ball valve and increase the reliability of the seal, oil seal ball valves have appeared in recent years, and the special lubricating oil is injected between the sealing faces to form an oil film, which enhances the sealing performance and reduces the operating torque. It is more suitable for high pressure and large diameter ball valves.
   Third, the elastic ball valve: The ball of the ball valve is elastic. Both the ball and the seat ring are made of metal material, and the sealing pressure is very large. The pressure of the medium itself cannot meet the sealing requirements, and an external force must be applied. This valve is suitable for high temperature and high pressure media. The elastic sphere is made by opening an elastic groove at the lower end of the inner wall of the sphere to obtain elasticity. When the passage is closed, the wedge of the valve stem is used to open the ball and press against the seat to seal. Before the ball is rotated, the wedge head is loosened, and the ball is restored to its original shape, so that a small gap occurs between the ball and the valve seat, which can reduce the friction and operating torque of the sealing surface.
  The closing part of the American standard stainless steel ball valve is a ball, which is a kind of valve that is opened and closed by rotating the ball around the center line of the valve body.
 The working principle of the American standard stainless steel ball valve is divided into two processes: opening and closing:
 First, the opening process
 1. In the closed position, the ball is pressed by the mechanical pressure of the valve stem and pressed against the valve seat.
 2. When the hand wheel is turned counterclockwise, the valve stem moves in the opposite direction, and the bottom angular plane causes the ball to disengage from the valve seat.
 3. The valve stem continues to lift and interacts with the guide pins in the spiral groove of the valve stem to cause the ball to rotate without friction.
 4. Until the fully open position, the valve stem is raised to the limit position and the ball is rotated to the fully open position.
 Second, the closing process
 1. When closing, turn the handwheel clockwise, the valve stem begins to descend and the ball moves away from the valve seat.
 2. Continue to rotate the hand wheel. The valve stem is subjected to the guide pin embedded in the upper spiral groove, so that the valve stem and the ball rotate at 90° at the same time.
 3. When it is about to close, the ball has been rotated 90° without contact with the valve seat.
 4. After a few turns of the zui of the handwheel, the angular plane at the bottom of the valve stem mechanically wedges against the ball, so that it is pressed tightly on the valve seat to achieve complete sealing.

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