Type of gate valve

1, according to the construction of the gate can be divided

(1) Parallel gate valves: two gate valves with parallel sealing surfaces.

In parallel gate valves, the structure with thrust wedge is often common, with double-sided thrust wedge in the middle of two gate plates. This type of gate valve is suitable for low pressure small diameter (DN40 -- 300mm) gate valves. There are also a spring between the two gates, the spring can produce a tight force, conducive to the seal of the gate.

(2) Wedge gate valve: two gate valves with a wedge shaped sealing surface.

The inclined Angle of the sealing surface is generally 2°52´, 3°30´, 5°, 8° and 10°, etc. The Angle mainly depends on the temperature of the medium. Generally, the higher the working temperature is, the larger the Angle should be, so as to reduce the possibility of wedging when the temperature changes. Tianjin gate valves

In wedge type gate valves, there are single, double and flexible gate. Single disc wedge gate valve, simple structure, can be used *, but on the accuracy of the sealing surface Angle requirements are higher, processing and maintenance is more difficult, the temperature changes when the possibility of wedge is very large. Double ram wedge gate valves are used in water and steam medium pipelines. Its advantages are: the accuracy requirements of the sealing surface Angle is low, temperature change is not easy to cause the phenomenon of wedging, the sealing surface wear, can add gasket compensation. But this kind of structure parts more, easy to bond in the viscous medium, affect the seal. More importantly, the upper and lower baffle for a long time to use easy to produce rust, the gate is easy to fall off. Elastic wedge gate valve, which has the advantages of simple structure and easy to use, can produce trace elastic deformation to make up for the deviation in the sealing surface Angle processing, and improve the process, has been widely used.

2, according to the structure of the valve stem 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 plate, the stem nut can be rotated to realize the rise and fall of the valve stem. This type of structure for stem lubrication, open and close degree is obvious, so it is widely used.

(2) Dark stem gate valve: stem nut is in the valve body, in direct contact with the medium. To open and close the gate, turn the stem. The advantage of this design is that the height of gate valves is always the same, so the installation space is small, suitable for large diameter or limited installation space of gate valves. The structure shall be equipped with an on/off indicator to indicate the degree of on/off. The disadvantage of this structure is that stem threads not only cannot be lubricated, but also directly accept the medium erosion, easy to damage.