Gate Valve's headstock is the gate, the movement direction of the brake plate and the fluid direction perpendicular, gate valve can only be fully open and full, cannot regulate and throttle. The brake board has two sealing surfaces, the most commonly used mode gate valve two sealing surfaces form wedge-shaped, wedge-shaped angle varies with valve parameter, usually 5 °, medium temperature is not high when 2 ° 52'. Wedge Gate valve can be made into a whole, called the rigid Gate plate, can also be made to produce micro-deformation of the brake pad to improve its craft, to compensate for the sealing surface in the processing of the angle of the deviation, such a brake board is called the elastic Brake board. When the gate valve closes, the sealing surface can be sealed only by the media pressure, i.e. relying on the media pressure to press the seal surface of the brake plate to the other side of the valve seat to ensure the sealing surface, which is self sealed. Most of the gate valves are forced sealed, that is, when the valve closes, it is necessary to rely on external forces to force the brake pad to the valve seat to ensure sealing surface. The gate of the floodgate valve is moving in a straight line with the stem, called the lifting rod gate valve, also called the Ming pole Gate valve. Usually on the lifting rod with trapezoidal screw threads, through the valve top of the nut and the valve body on the guide Groove, rotating movement into a straight-line movement, that is, the operation of torque into operation Thrust. When opening the valve, when the gate lifting height equals the valve diameter 1:1 time times the fluid passage is completely unblocked, but at run time, this location is not monitored. In actual use, it is the vertex of the valve stem as a symbol, that is, the position of the open, as its full swing. In order to consider the temperature change of the deadlock phenomenon, usually in the vertex position, and then back to the 1/2-1 circle, as the open valve position. Therefore, the valve's fully open position, according to the position of the brake board to determine the stroke. Some gate valve, stem nut is located on the brake board, handwheel rotation drive stem rotation, and to enhance the brake board, this valve is called rotary rod gate valve, or the dark pole gate valve.