Gate Valve Working Principle - Surface Valve Manufacturers

A gate valve is a type of valve which restricts fully the flow of fluids. Or, valves that give full bore flow without change of directions.

Gate Valve Working Principle | How does a Gate Valve work?

A gate valve refers to a valve in which the closing member (gate) moves in the vertical direction of the centerline of the passage. The gate valve can only be used for fully open and fully closed shut-off in the pipeline, and cannot be used for adjustment and throttling. A gate valve is a kind of valve with a wide range of use. Generally, DN50 cut-off devices are selected for use, and sometimes gate valves are also used for cut-off devices with small diameters. The gate valve is used as a cut-off medium, and the whole flow is straight when it is fully opened. At this time, the pressure loss of the medium is minimal. Gate valves are usually suitable for working conditions that do not need to be opened and closed frequently and keep the gate fully open or fully closed. Not suitable for use as regulation or throttling. For the high-speed flowing medium, the gate can cause a vibration of the gate when it is partially opened, and the vibration may damage the sealing surface of the gate and the valve seat, and the throttling will cause the gate to be eroded by the medium.

From the structural form, the main difference is the form of the sealing element used. According to the form of sealing elements, gate valves are often divided into several different types, such as wedge gate valve, parallel gate valve, parallel double gate valve, wedge double gate valve, etc. The most commonly used forms are wedge gate valves and parallel gate valves.

The gate has two sealing surfaces. The two sealing surfaces of the most commonly used wedge gate valve form a wedge. The wedge angle varies with valve parameters, usually 5 degrees. 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 sealing surface angle 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 seat by an 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 into 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 a mark, that is, the position where it cannot be opened, as its fully open position. In order to take into account the locking phenomenon due to temperature changes, it is usually opened to the top position, and then back 1/2~1 turn, as the position of the fully open valve. Therefore, the fully open position of the valve is determined by the position of the gate (that is, the stroke).

Gate Valve Parts Name

Handwheel
- This is a wheel that is rotated clockwise and anticlockwise.
Stuffing box
- A chamber in which the packing is compressed.
Packing material
- A gasket is required for a reliable seal between the stem and the bonnet. This is known as packing. This consist of the following components
Bonnet
- The bonnet is the cover for the opening in the body and is the pressure valve’s second most important boundary. Bonnets, like valve bodies, come in a variety of styles and models.
Gasket
- It is fitted between the body and the bonnet.
Stem
- The valve stem is responsible for the proper positioning of the disk and provides the necessary movement to the disc, plug, or ball for opening or closing the valve. On one end, it is connected to the valve handwheel, actuator, or lever, and on the other end, it is connected to the valve disc. The disc in a gate or globe valve must move linearly to open or close the valve, whereas the disc in a plug, ball, or butterfly valve must rotate to open or close the valve.
Flange
- It is for tightening the gland with a nut.
Gate/Disk
- Depending on its position, the disc allows, throttles, or stops the flow. In the case of a plug or a ball valve, the disc is referred to as a plug or a ball. The disk is the third most important primary pressure boundary. When the valve is closed, the full system pressure is applied across the disk, and as a result, the disk is a pressure-related component.
Valve body
- The primary boundary of a pressure valve is the valve body, also known as the shell. Because he is the framework that holds all the parts together, he is the most important component of a valve assembly.