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The main purpose of the gate valve

Posted by Bundor valve
What is the main purpose of the gate valve? The gate valve has a wide range of applications. Generally, it is used for blocking devices with a diameter of DN ≥ 50mm, and sometimes gate valves are also used for blocking devices with small diameters. The main function of the gate valve is to use it as a cut-off medium. When it is fully opened, it runs smoothly, and the pressure loss of the medium is minimal at this time. Gate valves are usually used in conditions that do not need to be opened and closed frequently, and keep the gate fully open or fully closed. They are not suitable for regulation or throttling use. For high-speed moving media, the gate can cause vibration of the valve 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 media.
The adaptability of gate valves is stronger than that of butterfly valves, and gate valves can be used in low and high temperature, or low and high pressure conditions. In steam pipelines and large-diameter water supply pipelines, gate valves are more suitable due to the need for higher sealing performance and less fluid resistance.

Advantages of gate valves
(1) Small fluid resistance: As the medium channel in the gate valve body is straight, the medium does not change its flow direction when it flows through the gate valve, so the fluid resistance is small.
(2) The opening and closing torque is small, and it’s more labor-saving because the gate movement direction is perpendicular to the medium flow direction when the gate valve is opened and closed comparing with globe valve.
(3) The flow direction of the medium is not restricted, and the medium can flow in any direction on both sides of the gate valve without disturbing the flow or reducing the pressure. It is more suitable for pipelines where the flow direction of the medium may change.
(4) The structural length is shorter because the gate of the gate valve is placed vertically in the valve body, while the disc of the globe valve is placed horizontally.
(5) The sealing performance is good. The sealing surface is less eroded when fully open.
(6) When the valve is fully opened, the erosion of the sealing surface is smaller than that of the globe valve.
(7) The shape is relatively simple, the casting process is good, and the scope of application is wide.
 
Disadvantages of gate valves
(1) The sealing surface is easy to be damaged. The two seals and gate have friction when you’re opening and closing  which affects the performance and service life of the seals. And it is difficult to maintain.
(2) The opening and closing time is long and it’s tall. Because the gate valve must be fully opened or closed. The gate travel is large, and a certain space is required. The external dimensions are high, and the installation space is large.
(3) Gate valves with complex structures generally have two sealing surfaces, which increase processing, grinding and maintenance. There are many difficult parts, manufacturing and maintenance are more difficult, and the cost is higher than that of globe valves.