1. According to the gate structure can be divided into 1) parallel gate valve: sealing surface and vertical centerline parallel, that is, two sealing surface parallel to each other gate valve. Parallel gate valve is usually double gate structure. In parallel gate valves, the structure with thrust wedges is the most common, with double-sided thrust wedges in the middle of the two gate plates. This type of gate valve is suitable for low pressure medium and small bore (DN40-300mm) gate valves. There is also a spring between the two rams, the spring can produce preload, is conducive to the gate seal. 2) wedge gate valve: sealing surface and the vertical center line into a certain angle, that is, two sealing surface into a wedge-shaped gate valve. The sealing surface of the tilt angle is generally 2 ° 52 ', 3 ° 30', 5 °, 8 °, 10 °, the size of the angle depends on the medium temperature level. The higher the general operating temperature, the angle taken should be greater in order to reduce the possibility of wedging occurs when the temperature changes. In the wedge gate valve, there is a single gate, double gate and elastic gate of the points. Single-gate wedge gate valve, simple structure, reliable, but the sealing surface angle of the higher precision, processing and maintenance more difficult, prone to clamping, abrasions, wedges the possibility of temperature changes great. Double gate wedge gate valve structure is more complex, more water and steam medium pipe. Its advantages are: low precision of the sealing surface angle, the temperature change is not easy to cause wedging phenomenon, the sealing surface wear, you can add gasket compensation. However, this structure more parts in the viscous medium easy to bond, affecting the seal. More importantly, the long-term use of the lower bezel easy to produce corrosion, easy to fall off the gate. The structure of the elastic gate wedge gate valve is characterized in that an annular groove is provided on the periphery of the gate so that the gate has an appropriate elasticity. It has the advantages of simple structure and reliable use of a single gate wedge gate valve, The elastic deformation to make up for the sealing surface angle of the deviation arising during the process to improve the process, has now been widely used. Special purpose gate valve, such as long-distance oil transmission, gas pipeline on the use of large-diameter gate valve for cleaning the needs of the pipeline and the use of a single gate structure. 2. Valve stem structure by the valve can be divided into 1) Ming rod valve: stem nut in the valve cover or bracket, the opening and closing of the gate, the use of rotating stem nut to achieve stem lifting. This structure is beneficial to the lubrication of the valve stem, opening and closing a clear degree, it is widely used. 2) dark bar gate valve: stem nut in the valve body, and the media in direct contact. Open and close the gate, the rotary valve stem to achieve. The advantage of this structure is that the height of the gate valve always remains unchanged, so the installation space is small, suitable for large-caliber or gate valves with limited installation space. This structure should be equipped with an opening and closing indicator to indicate the degree of opening and closing. The disadvantage of this structure is that not only is the stem thread unlubricated, but it is also subject to direct media erosion and damage. 3, the gate valve diameter contraction If a valve body of the channel diameter is not the same (often at the valve seat diameter less than the diameter of the flange connection), known as the diameter of the contraction. Path contraction can reduce the size of the parts, opening and closing the corresponding reduction in force required, while expanding the scope of application of components. However, after the path of contraction. Fluid resistance loss increases. Under certain operating conditions in certain sectors (such as oil pipelines in the petroleum sector), valves with reduced diameter are not allowed. This is done on the one hand to reduce the loss of resistance on the part of the pipeline and on the other hand to avoid obstacles to the mechanical cleaning pipeline after the shrinkage of the path. Search Keyword: More Valve Technical Articles