Make Severe Service Flow Control Easy

What is a gate valve?

Verspec Valve 1273

Working principle

    The opening and closing part of the gate valve is a gate. The movement direction of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed, and cannot be adjusted or throttled. The gate has two sealing surfaces. The two sealing surfaces of the most commonly used mode gate valve form a wedge. The wedge angle varies with valve parameters, usually 5°, and 2°52' when the medium temperature is not high. The gate of the wedge gate valve can be made into a whole, called a rigid gate; it can also be made into a gate that can produce slight deformation to improve its manufacturability and make up for the deviation of the angle of the sealing surface during the processing. The plate is called an elastic gate. When the gate valve is closed, the sealing surface can only rely on the medium pressure to seal, that is, relying on the medium pressure to press the sealing surface of the gate to the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, the gate must be forced against the valve seat by external force to ensure the tightness of the sealing surface. The gate valve of the gate valve moves linearly with the valve stem, which is called the lifting stem gate valve, also called the rising stem gate valve. Usually there is a trapezoidal thread on the lifting rod, through the nut on the top of the valve and the guide groove on the valve body, the rotary motion is changed to linear motion, that is, the operating torque is turned into operating thrust. When the valve is opened, when the lift height of the gate is equal to 1:1 times the valve diameter, the fluid passage is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as the mark, that is, the unmovable position, as its fully open position. In order to take into account the locking phenomenon due to temperature changes, it is usually opened to the apex position, and then rewind 1/2-1 circle as the fully open valve position. Therefore, the fully open position of the valve is determined by the position of the gate, that is, the stroke. In some gate valves, the stem nut is set on the gate, and the rotation of the handwheel drives the rotation of the valve stem to lift the gate. This kind of valve is called a rotating stem gate valve, or a dark stem gate valve.


Mode of motion

    When the gate valve is closed, the sealing surface can only bear the medium pressure to seal, that is, only the medium pressure is connected to press the sealing surface of the gate to the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, it must bear the external force to force the gate to the valve seat to ensure the tightness of the sealing surface.
    Movement mode: The gate of the gate valve moves linearly along with the valve stem, which is also called a rising stem gate valve. Usually there is a trapezoidal thread on the lifting rod. The nut at the end of the valve and the guide groove on the valve body convert the rotary motion into a straight line to open the valve. When the lift height of the gate is equal to 1:1 times the valve diameter, the fluid channel It is completely unblocked, but this position cannot be monitored during operation. In actual use, the top of the valve stem is used as a mark, that is, the position where it cannot be opened, as its fully open position. In order to take into account the lock-up phenomenon caused by temperature changes, it is usually opened to the top position, and then back 1/2-1 circle, as the fully open valve position. Therefore, the fully open position of the valve is determined by the position of the gate (that is, stroke). Some gate valve stem nuts are installed on the gate, and the rotation of the handwheel drives the rotation of the valve stem to lift the gate. This kind of valve is called Rotating stem gate valve or dark stem gate valve.


advantage

  1. Small flow resistance. The medium channel inside the valve body is straight, the medium flows in a straight line, and the flow resistance is small.
  2.  Less effort when opening and closing. It is compared with the shut-off valve, because whether it is open or closed, the direction of movement of the gate is perpendicular to the direction of medium flow.
  3.  Large height and long opening and closing time. The opening and closing stroke of the gate is relatively large, and the lifting is carried out by the screw.
  4.  Water hammer is not easy to produce. The reason is the long closing time.
  5.  The medium can flow in any direction on both sides, easy to install. Both sides of the gate valve channel are symmetrical.
  6.  The structural length (the distance between the two connecting end faces of the shell) is small.
  7.  Simple shape, short structure length, good manufacturing technology and wide application range.
  8.  Compact structure, good valve rigidity, smooth passage, small flow resistance, stainless steel and hard alloy sealing surface, long service life, PTFE packing, reliable sealing, light and flexible operation.

Disadvantage
    It is easy to cause erosion and scratches between the sealing surfaces, and maintenance is difficult. The overall size is large, opening requires a certain amount of space, and the opening and closing time is long. The structure is more complicated.


Company Profile

2005——Start to produce ceramic lined valve series.

2006——Start to produce rubber seat dome valve, knife gate valve and pinch valves.

2010——Joint venture start to produce Teflon plastic lined valve series.

2016——VerSpec US warehouse operated in Akensas.

2018——VerSpec Korea branch operated in Cheonnam.

2019——VerSpec India and VerSpec Mexico start operating.

www.verspec.com
Tel: +86-577-57666870  
Fax:+86-577-56769885
E-mail: info@verspec.com

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