1. It can be divided according to the plan of the gate
1) Parallel gate valve: The sealing surface is parallel to the vertical base line, that is, a gate valve with two sealing surfaces parallel to each other.
In parallel gate valves, the planning with thrust wedge is more common. There are double-sided thrust wedge at the base of the two gates. This kind of gate valve is suitable for low-pressure medium and small diameter (DN40-300mm) gate valves. There are also those with a spring between the two gates. The spring can generate pre-tightening force, which is conducive to the sealing of the gate.
2) Wedge gate valve: The sealing surface is at a certain angle to the vertical base line, that is, the two sealing surfaces are wedge-shaped gate valves. The inclination angle of the sealing surface is usually 2°52', 3°30', 5°, 8°, 10°, etc. The size of the angle mainly depends on the unevenness of the medium temperature. Generally, the higher the working temperature, the larger the angle should be to reduce the possibility of wedging when the temperature is changed. In the wedge gate valve, there are single gate, double gate and elastic gate. The single gate wedge gate valve has simple planning and reliable operation, but requires high accuracy of the angle of the sealing surface, processing and repairing are more difficult, and the possibility of wedging when the temperature is changed is great. Double ram wedge gate valves are widely used in water and steam media pipelines. Its benefits are: the accuracy of the angle of the sealing surface needs to be lower, the temperature change is not easy to cause the phenomenon of wedging, and the sealing surface can be compensated when the sealing surface is worn. However, there are many parts of this kind of planning, which are easy to stick in the viscous medium, which affects the sealing. More importantly, the upper and lower baffles are prone to rust when used for a long time, and the gates simply fall off. The elastic gate wedge gate valve has a simple plan for a single gate wedge gate valve. It has the advantages of safe use, and can generate a small amount of elastic deformation to compensate for the deviation of the sealing surface angle processing, and improve the technicality. It has been used by many .
2. According to the planning of the valve stem, the gate valve can be divided into
1) Rising stem gate valve: The stem nut is on the valve cover or bracket. When opening and closing the gate, use the rotating stem nut to complete the lifting of the stem. This kind of planning is beneficial to the lubrication of the valve stem, and the degree of opening and closing is obvious, so it is widely used.
2) Dark stem gate valve: The stem nut is in the valve body and touches the medium directly. When opening and closing the gate, use the rotating valve stem to finish. The benefit of this kind of planning is that the height of the gate valve is always the same, so the equipment space is small, and it is suitable for gate valves with large diameters or restricted equipment space. Such a plan should be equipped with an opening and closing indicator to indicate the degree of opening and closing. The disadvantage of this kind of planning is that the valve stem thread not only cannot be lubricated, but it is directly corroded by the medium and is simply damaged.
