Introduction to the relevant knowledge of the national standard globe valve

The GB shut-off valve is a forced-sealed valve, so when the valve is closed, pressure must be applied to the valve flap to force the sealing surface to not leak. When the medium enters the valve six from below the valve flap, the resistance to be overcome by the operating force is the friction between the valve stem and the packing and the thrust generated by the pressure of the medium. The force of closing the valve is greater than the force of opening the valve, so the valve The diameter of the rod is large, otherwise the valve stem may be bent.
 

In recent years, after the appearance of the self-sealing valve, the flow direction of the flange stop valve is changed from the valve flap to the valve chamber. At this time, under the action of the medium pressure, the force to close the valve is small, and the force of opening the valve is large, the valve The diameter of the rod can be correspondingly reduced. At the same time, this type of valve is also tight under the action of the medium. China's valve "three-way to give" has stipulated that the flow of the stop valve, all from top to bottom.