Gate valve overview

The gate valve refers to a valve in which the closing member (gate) moves in the vertical direction of the center line of the passage. The gate valve is mainly used for cutting in the pipeline.
The gate valve is a widely used valve. It is generally used for cutting devices with a diameter of DN ≥ 50 mm. Sometimes the cutting device with a small diameter also uses a gate valve. The gate valve has the following advantages: 1 The fluid resistance is small. 2 The external force required for opening and closing is small. 3 The flow direction of the medium is not limited. 4 When fully open, the sealing surface is less affected by the working medium than the shut-off valve. 5 body shape is relatively simple, casting process is better.
Gate valves also have shortcomings: 1 Both the external dimensions and the opening height are large. The space required for installation is large. 2 During the opening and closing process, there is relative friction between the sealing surfaces, which is likely to cause scratches. 3 Gate valves generally have two sealing faces, adding some difficulties to machining, grinding and maintenance.
According to the structure of the gate valve, the gate valve can be divided into: (1) Parallel gate valve: the sealing surface is parallel to the vertical center line, that is, the gate valves whose two sealing surfaces are parallel to each other. In the parallel gate valve, the structure with thrust wedges is often common, and there are double-sided thrust wedges in the middle of the two gates. This gate valve is suitable for low-pressure medium and small diameter (DN40-300mm) gate valves. There is also a spring between the two shutters, and the spring can generate a pre-tightening force, which is beneficial to the sealing of the shutter. (2) Wedge gate valve: the sealing surface is at an angle to the vertical center line, that is, the gate valve with two sealing surfaces forming a wedge shape. The angle of inclination of the sealing surface is generally 2°52 ́, 3°30 ́, 5°, 8°, 10°, etc. The angle depends mainly on the temperature of the medium. Generally, the higher the working temperature, the larger the angle should be taken to reduce the possibility of wedges when the temperature changes.