截止阀和闸阀的区别（The difference between cut-off valve and gate valve）.doc

截止阀和闸阀的区别（The difference between cut-off valve and gate valve） The working principle is different. The stop valve is an upward stem type, and the handwheel rotates and rises with the stem. Valve is hand wheel rotation, stem upward movement. Flow is not the same, the gate valve requires full open, the cut-off valve is not the same. The gate valve has no inlet and outlet direction requirements, and the cut-off valve has the required inlet and outlet! Gate valve and stop valve are shut-off valve, is the most common two valves. From the exterior, the gate valve is shorter than the cut-off valve, especially the bar valve needs a higher height space. Valve sealing surface has a certain degree of self sealing capacity, its spool depends on the media pressure tight contact with the valve seat sealing surface, to achieve tight leakage. Wedge gate valve spool angle is generally 3~6 degrees, when forced to shut down excessive or temperature changes of the valve core is easy to die. Therefore, high temperature and high pressure wedge gate valve, in the structure have taken certain measures to prevent spool stuck. The valve in the opening and closing valve and valve seat sealing surface contact and mutual friction is always so easy to wear sealing surface, especially in close off the valve, the valve before and after the great pressure, sealing surface wear is more serious. Compared with the cut-off valve, the main advantage is that the flow resistance is small, the flow resistance coefficient of ordinary gate valve is about 0.08~0.12, while the ordinary cut-off valve resistance coefficient is about 3.5~4.5. Opening, closing force is small, the medium can flow in two directions. The disadvantage is that the structure is complex and the height is large. The sealing surface is easy to wear. The sealing surface of the valve must be forced to close the valve to achieve sealing, in the same caliber, work pressure and the same drive device, the drive valve torque is 2.5~3.5 times the