The opening and closing part of the gate valve is a gate. The movement direction of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed, and cannot be adjusted or throttled. The gate has two sealing surfaces. The two sealing surfaces of the most commonly used model gate valve form a wedge. The wedge angle varies with valve parameters, usually 50, and 2°52' when the medium temperature is not high. The gate of the wedge gate valve can be made into a whole, called a rigid gate; it can also be made into a gate that can produce a small amount of deformation to improve its manufacturability and make up for the deviation of the sealing surface angle during the processing. Elastic gate

The types of gate valves can be divided into wedge gate valves and parallel gate valves according to the sealing surface configuration. Wedge gate valves can be further divided into: single gate type, double gate type and elastic gate type; parallel gate type gate valves can be divided into It is single gate type and double gate type. Divided according to the thread position of the valve stem, it can be divided into two types: open stem gate valve and dark stem gate valve. When the gate valve is closed, the sealing surface can only rely on the medium pressure to seal, that is, rely on the medium pressure to press the sealing surface of the gate to the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, the gate must be forced to the valve seat by external force to ensure the tightness of the sealing surface.

The gate of the gate valve moves linearly with the valve stem, which is called the lifting stem gate valve (also called the rising stem gate valve). Usually there is a trapezoidal thread on the lifting rod, through the nut on the top of the valve and the guide groove on the valve body, the rotary motion is changed into linear motion, that is, the operating torque is turned into operating thrust.

When the valve is opened, when the lift height of the gate is equal to 1:1 times the valve diameter, the fluid passage is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as the mark, that is, the unmovable position, as its fully open position. In order to take into account the lock-up phenomenon caused by temperature changes, it is usually opened to the apex position, and then back 1/2-1 turn, as the position of the fully open valve. Therefore, the fully open position of the valve is determined according to the position of the gate (that is, stroke). In some gate valves, the stem nut is set on the gate, and the rotation of the handwheel drives the rotation of the valve stem to lift the gate. This kind of valve It is called a rotating rod gate valve or a dark rod gate valve.

The installation and maintenance of the gate valve should pay attention to the following matters: 1. Handwheels, handles and transmission mechanisms are not allowed to be used for lifting, and collisions are strictly prohibited. 2. The double gate valve should be installed vertically (that is, the valve stem is in the vertical position and the handwheel is on the top). 3. The gate valve with a bypass valve should be opened before opening (to balance the pressure difference between the inlet and outlet and reduce the opening force). 4. The gate valve with transmission mechanism should be installed according to the product manual. 5. If the valve is frequently opened and closed, lubricate at least once a month.

Features of elastic seat seal gate valves: The general gate valves used on the market for a long time generally have water leaks or rust. For defects such as rust, the elastic seat-sealed gate valve uses the compensation effect of the small elastic deformation of the elastic gate to achieve a good sealing effect. The valve has the obvious advantages of light switch, reliable sealing, good elastic memory and service life.