1. Low fluid resistance.
2. The external force required for opening and closing is small.
3. The flow direction of the medium is not bound.
4. When fully open, the erosion of the sealing surface by the working medium is smaller than that of the stop valve.
5. The shape comparison is simple, and the casting technology is good.
Disadvantages of gate valve
1. The overall dimension and opening height are large. The equipment requires large space.
2. In the process of opening and closing, there is a relative conflict between the sealing surfaces, which briefly causes scratch.
3. Gate valves usually have two sealing surfaces, which adds some difficulties to processing, grinding and repair.
Types of gate valves
1. It can be divided according to the planning of ram
1) Parallel gate valve: the sealing surface is parallel to the vertical base line, that is, the two sealing surfaces are parallel to each other.
Among the parallel gate valves, the planning with thrust wedge is more common. There are double-sided thrust wedge at the base of two gate valves. This kind of gate valve is suitable for low-pressure medium and small diameter (dn40-300mm) gate valves. There are also springs between the two rams, which can exert pre tightening force, which is conducive to the sealing of the ram.
2) Wedge gate valve: the sealing surface forms an angle with the vertical base line, that is, the two sealing surfaces form a wedge-shaped gate valve. The inclined angle of the sealing surface is usually 2 ° 52 ‘, 3 ° 30′, 5 °, 8 °, 10 °, etc. the size of the angle mainly depends on the concave convex of the medium temperature. Generally, the higher the working temperature is, the larger the angle should be, so as to reduce the possibility of wedging when the temperature is changed. In wedge gate valve, there are single gate valve, double gate valve and elastic gate valve. The single gate wedge gate valve has simple planning and reliable operation, but it needs high accuracy for the angle of the sealing surface, which is difficult to process and repair, and it can be wedged when the temperature is changed. Double gate wedge gate valves are widely used in water and steam medium pipelines. Its benefits are: the accuracy of the angle of the sealing surface needs to be low, and the temperature change is not easy to cause the scene of wedging. When the sealing surface is worn, it can be padded for compensation. However, this kind of planning has many parts, which are easy to bond in viscous medium and affect the sealing. More importantly, the upper and lower baffles are easy to rust after long-term use, and the ram is easy to fall. Elastic gate wedge gate valve, which has the simple planning of single gate wedge gate valve, can produce a small amount of elastic deformation to compensate for the deviation in the angle processing of sealing surface and improve the technicality by using the * benefits, and has been selected by many.
2. According to the planning of the valve stem, the gate valve can be divided into
1) Rising stem gate valve: the valve stem nut is on the valve cover or support. When opening and closing the gate, rotate the valve stem nut to complete the lifting of the valve stem. This kind of planning is beneficial to the lubrication of the valve rod, and the opening and closing degree is obvious, so it is widely used.
2) Non rising stem gate valve: the valve stem nut is in the valve body and directly touches the medium. When opening and closing the ram, rotate the valve rod. The benefit of this plan is that the height of the gate valve always remains unchanged, so the equipment space is small. It is suitable for gate valves with large diameter or constrained equipment space. Such planning shall be equipped with opening and closing indicators to indicate the opening and closing degree. The disadvantage of this plan is that the stem thread is not only unable to be lubricated, but also directly eroded by the medium and slightly damaged.
The diameter of gate valve is shortened
Assuming that the channel diameter in a valve body is different (usually the diameter at the valve seat is smaller than that at the flange connection), it is called path shortening.
Reducing the drift diameter can reduce the size of parts and the force required for opening and closing. Together, it can expand the application planning of parts.
After reducing the drift diameter. Fluid resistance increases.
Post time: May-09-2022