Share some knowledge about gate valve principle!

Gate valve can only be fully open or fully closed, can not be used as zd section flow valve.Its working principle is that the gate with the stem plate up and down with straight movement, the stem has a trapezoidal thread, through the nut at the top of the valve and the guide groove on the body, to achieve the weight of the stem up and down movement, the stem drive the gate movement.The direction of gate movement is perpendicular to the direction of the pipe medium.

When the valve is open, the rising stem gate valve can be determined by observing the exposed stem position;For the dark stem gate valve, is unable to view, generally to open up as far as the complete open sign, but in consideration of the temperature may be locked, the general gate valve open end, that is, the open position, then about 1/2 turn, as the gate valve fully open position.
When the gate valve is closed, the sealing surface can be sealed only by the pressure of the medium, that is, the pressure of the sealing surface of the gate to the other side of the seat to ensure the sealing surface, this is self-sealing.Most gate valves are used for forced sealing, that is, when the valve is closed, to rely on external force to force the gate to the seat, in order to ensure the sealing surface of the seal.