法兰楔式闸阀
Flange wedge gate valve
闸阀关闭时 , 密封面可以只依靠介质压力来密封 , 即只依靠介质压力将闸板的密封面压向另一侧的阀座来保证密封面的密封，这就是自密封。大部分闸阀是采用强制密封的 , 即阀门关闭时，要依靠外力强行将闸板压向阀座 , 以保证密封面的密封性。  闸阀的闸板随阀杆一起作直线运动的，叫 ( 亦叫明杆闸阀)。通常在升降杆上 有梯形螺纹，通过阀门顶端的螺母以及阀体上的导槽，将旋转运动变为直线运动 , 也就是将操作转矩变为操作推力。  开启阀门时，当闸板提升高度等于阀门通径的1：1倍时，流体的通道完全畅通，但在运行时，此位置是无法监视的。实际使用时，是以阀杆的顶点作为标志，即开不动的位置，作为它的全开位置。为考虑温度变化出现锁死现象 , 通常在开到顶点位置上 , 再倒回 1/2－1圈 , 作为全开阀门的位置。因此 , 阀门的全开位置，按闸板的位置（即行程〉来确定。  有的闸阀 , 阀杆螺母设在闸板上，手轮转动带动阀杆转动 , 而使闸板提升 , 这种阀门叫做旋转杆闸阀或叫暗杆闸阀
When the gate valve is closed, the sealing surface can only rely on the medium pressure to seal, that is to say, only rely on the medium pressure to press the sealing surface of the gate valve to the valve seat on the other side to ensure the sealing of the sealing surface, which is self sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, the gate shall be forced against the valve seat by external force to ensure the sealing of the sealing surface. The gate of the gate valve moves in a straight line with the stem, which is also called rising stem gate valve. Generally, there is trapezoid thread on the lifting rod. Through the nut at the top of the valve and the guide groove on the valve body, the rotating motion is changed into linear motion, that is, the operating torque is changed into the operating thrust. When opening the valve, when the lifting height of the ram is equal to 1:1 times of the valve diameter, the flow passage is completely unblocked, but this position cannot be monitored during operation. In actual use, the vertex of the valve rod is taken as the mark, that is, the position that can not be opened is taken as its full open position. In order to consider the phenomenon of locking due to the change of temperature, the valve is usually opened to the vertex position, and then turned back 1 / 2-1 circle as the position of fully open valve. Therefore, the full open position of the valve is determined by the position of the RAM (i.e. stroke). Some gate valves, the stem nut is set on the gate, and the hand wheel rotates to drive the stem to rotate, so as to lift the gate. This kind of valve is called rotary stem gate valve or concealed stem gate valve