Type of gate valve Gate valve type, according to the sealing surface can be divided into wedge gate valve and gate-type gate valve. Wedge gate valve can be divided into: single gate, double gate and elastic gate type; parallel gate valve can be divided into single gate and double gate type. According to the thread position of the stem division, can be divided into Ming rod valve and dark rod gate valve two. z41h flange wedge gate valve is closed, the sealing surface can only rely on medium pressure to seal, that is, only rely on media pressure to the sealing surface of the gate to the other side of the valve seat to ensure that the sealing surface of the seal, which is self-sealing . Most of the gate valve is forced seal, that is, when the valve is closed, it must rely on external force to force the gate to the valve seat to ensure the sealing surface of the seal. Gate valve gate along with the stem for linear motion, called Ming pole valve. Trapezoidal thread is usually on the lifting rod, through the valve at the top of the nut and the guide groove on the valve body, the rotary motion into a linear motion, that is, the operating torque into the thrust. When the valve is opened, the fluid path is completely clear when the ram height is equal to 1: 1 of the valve diameter, but this position can not be monitored during operation. The actual use is based on the top of the valve stem as a sign, that is, an open position, as its fully open position. To consider the temperature change lock phenomenon, usually in the open to the top position, and then back 1 / 2-1 lap, as a fully open valve position. Therefore, the valve fully open position, according to the gate position (ie stroke> to determine. Some gate valve, the stem nut is located in the gate, the hand wheel rotates the valve stem to rotate, leaving the ram to lift, this valve Known as rotary rod valve or dark rod gate valve.