The gate valve refers to the gate with the vertical motion trail along the central path of the gate closure. Generally consisted by the valve body, the seat, the stem, the wedge, the bonnet and the seal ring, it can be transformed by configuration of transmission devices into a variety of electric and pneumatic gate valves. Since it can only be fully switched on-and-off in the pipeline, never can it be a regulator or a throttle.
Together with the stem, the gate wedge is in the state of linear motion. The rotary movement, achieved by the top nut and the guide groove rotating alongside the lift rod trapezoidal screw, turns into a linear motion, thereby turning the operating torque into the operating thrust.
The sealing surface can rely on the media pressure to seal itself, that is, the media pressure push the sealing surface to the the other side of the gate to achieve the sealing. It is also called the self-sealing. Most of the gate valves are forced sealing ones, that is, the external pressure push its wedge to the seat to ensure the sealing.
When the gate is raised to a height equal to 1:1 of the valve diameter, the fluid channel is fully open. However, it is impossible to monitor during operation. In actual use, the apex of the stem serves as a symbol of a full open, that is, the fixed position signifies its full open. To take the temperature-caused lock into account, turning to the apex with an afterward 1 / 2-1 round back as a full-open position. Therefore, whether it is a full open is determined by the position of the gate wedge (i.e. stroke).