Cast Steel Gate Valve 4

When the gate valve closes, the sealing surface can be sealed only by the medium pressure, that is to say, only by the medium pressure to press the sealing surface of the gate to the seat on the other side to ensure the sealing surface, which is self-sealing. Most gate valves are forced to seal, that is, when the valve closes, the gate must be forced to the seat by external force to ensure the sealing surface.

Motion mode: The gate of the gate valve moves in a straight line with the stem, also known as the open bar gate valve. Usually there are trapezoidal threads on the lifting rod. Through the nut at the top of the valve and the guide groove on the valve body, the rotary motion is changed into linear motion, that is to say, the operating torque is changed into the operating thrust. When opening the valve, when the gate lifting height is equal to 1:1 times the valve diameter, the flow passage is completely open, but in operation, this position can not be monitored. In practical use, the vertex of the valve stem is used as the sign, that is, the position of the valve stem that is not moving is used as its full open position. In order to consider the locking phenomenon of temperature change, it is usual to turn back 1/2-1 circle at the top position as the position of the fully open valve. Therefore, the full open position of the valve is determined by the position of the gate (i.e. stroke). Some gate valve stem nuts are set on the gate plate. Handwheel rotation drives the stem to rotate, which lifts the gate plate. This kind of valve is called rotary stem gate valve or dark stem gate valve.