When the gate valve is closed, the sealing surface can only rely on the medium pressure to seal, that is to rely on the medium pressure to press the seal surface of the gate to the other side of the valve seat to ensure sealing surface, this is the self sealing. Most of the gate valves are forced seal, that is, when the valve is closed, it is necessary to force the gate to be pressed to the seat by external forces to ensure sealing of the seal surface.
Movement mode: Gate valve of the gate with the valve stem for a straight line movement, also known as the Ming rod gate valve. Usually, there is a trapezoidal thread on the lifter, through the nut on the top of the valve and the guide groove on the valve body, turning the rotation movement into a straight line motion, that is, turning the operation torque into operational thrust. When opening the valve, when the gate lifting height is equal to the valve diameter of 1:1 time times, the flow of the channel is fully unblocked, but at run time, this location is not monitored. In actual use, it is the vertex of the stem as a sign, that is, the position of the open, as its full opening position. In order to consider the phenomenon of temperature change deadlock, usually in the vertex position, and then pour back to the 1/2-1 circle, as the position of open valve. Therefore, the open position of the valve, according to the position of the gate (that is, stroke) to determine. Some gate valve stem nut is located on the brake board, the handwheel rotates to drive the stem to rotate, and make the gate ascend, this kind of valve is called the revolving rod gate valve or called the Dark Pole gate valve.