Author: Site Editor Publish Time: 2019-07-19 Origin: Site
The opening and closing part of the gate valve is a gate. The direction of movement of the gate is perpendicular to the direction of the fluid. The industrial gate valve can only be fully open and fully closed, and cannot be adjusted and throttled.
List of content for this article：
1. Difference structures of the gate valve,
2. Stem differences for the gate valve,
3. the diameter of the gate valve shrinks.
1, According to the structure of the gate can be divided into:
1) Parallel gate valve: the sealing surface is parallel to the vertical centerline, that is, the gate valves whose two sealing surfaces are parallel to each other.
Among the parallel gate valves, the structure with thrust wedges is most 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 centerline, 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.
2, According to the structure of the valve stem can be divided into:
1) Rising stem gate valve: The stem nut is on the bonnet or bracket. When opening and closing the gate, use the rotary stem nut to raise and lower the stem. This structure is advantageous for the lubrication of the valve stem, and the degree of opening and closing is obvious, so it is widely used.
2) Non-rising stem gate valve: The stem nut is in the valve body and is in direct contact with the medium. When opening and closing the shutter, use a rotary valve stem to achieve. The advantage of this structure is that the height of the gate valve remains the same, so the installation space is small, and it is suitable for large-diameter or gate valves with limited installation space. This structure is equipped with an opening and closing indicator to indicate the degree of opening and closing. The disadvantage of this type of construction is that the stem thread is not only lubricated but also directly etched by the medium and is easily damaged.
3, The diameter of the gate valve shrinks
If the diameter of the passage in a valve body is different (often the diameter of the valve seat is smaller than the diameter of the flange joint), it is called the diameter contraction.
The shrinkage of the diameter can reduce the size of the parts, reduce the force required for opening and closing, and expand the application range of the parts. But after the path is contracted.The fluid resistance loss increases.