The opening and closing parts of the wedge gate valve are the gate, the direction of motion of the gate is perpendicular to the fluid direction. The wedge gate valve can only be fully opened and fully closed and can not be adjusted and throttled. The gate has two sealing surfaces, the two sealing faces of the wedge gate valve usually form a wedge. The wedge angle varies according to the valve parameters, usually 5 degrees. If the media temperature is not high it is 2°52′. The gate of the wedge gate valve can be integrated, called a solid gate. Or it can be made into a gate that can produce trace deformation to improve its manufacturability and make up for the deviation of the sealing surface angle during processing, which is called the flexible gate.
Wedge Gate Valve Working principle
When the wedge gate valve is closed, the sealing surface can be sealed only by the media pressure. That is, only by relying on the media pressure to press the sealing surface to the other side of the seat to ensure the seal of the sealing surface, which is called self-sealing. Most of the wedge gate valve is a forced seal. That is, when the valve is closed, it is necessary to force the gate toward the valve seat by an external force to ensure the sealing of the sealing surface.
Movement patterns: The gate of the wedge gate valve moves linearly with the stem, also known as the os&y gate valve. Usually there are trapezoidal threads on the lift rod, which turns the rotational motion into straight movement through the nuts at the top of the valve and the guide groove on the valve body, that is, change the operating torque into the operating thrust. When opening the wedge gate valve, the channel of the fluid is completely clear when the height of the gate lift is equal to 1:1 times of the valve size. But this position is not monitorable during operation. In actual use, it is marked by the vertex of the stem, the position where it is not moving, as its full open position. In order to consider the phenomenon of lock-up due to temperature change, it is usually opened to the apex position, and then back to 1/2-1 circle as the position of the fully open valve. Therefore, the full opening position of the wedge gate valve is determined by the position of the gate (i.e. the stroke). Some gate valve stem nuts are set on the gate, and the rotation of the hand wheel drives the stem to rotate, which raises the gate, this wedge gate valve is called rotary stem wedge gate valve or non-rising stem wedge gate valve.
Wedge Gate Valve Advantages and disadvantage
Advantages of wedge gate valve
- The flow resistance is small. The internal media channel of the wedge gate valve body is straight through, the medium flows in a straight line and the flow resistance is small.
- Less effort when opening and closing. Compared with the globe valve, because no matter it is open or closed, the movement direction of the gate is perpendicular to the flow direction of the medium.
- Large height, long opening and closing time. The opening and closing stroke of the gate is large, and the lifting is performed by the screw.
- Water hammer phenomenon is not easy to produce for wedge gate valve. The reason is the long shutdown time.
- The media can flow in any direction on both sides of wedge gate valve, easy to install. Both sides of the gate channel are symmetrical.
- The face to the face dimension of wedge gate valve is small.
- Simple form, short structure length, good manufacturability and wide range of application.
- The structure is compact, the wedge gate valve has good rigidity, the channel is smooth, the flow resistance is small, the sealing surface is made of stainless steel and hard alloy, and the service life is long. The use of PTFE packing is reliable and easy to operate.
Disadvantages of wedge gate valve
- Erosion and scratches are easily caused between the sealing surfaces, and maintenance is difficult. Large size, need some space to open, long time to open and close. The structure of wedge gate valve is more complicated.
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