Stainless steel globe valves belong to forced sealing valves, so when the valve is closed, pressure must be applied to the valve disc to force the sealing surface to not leak. When the medium enters the valve from below the valve disc, the resistance that needs to be overcome by the operating force is the frictional force between the valve stem and packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open it, so the diameter of the valve stem should be larger, otherwise it will cause the valve stem to bend. In recent years, with the emergence of self sealing valves, the medium flow direction of globe valves has changed from above the valve disc to enter the valve chamber. At this time, under the pressure of the medium, the force to close the valve is small, while the force to open the valve is large, and the diameter of the valve stem can be correspondingly reduced. At the same time, under the action of the medium, this form of valve is also relatively tight. The "Three Modernizations" of valves in our country once stipulated that the flow direction of globe valves should be from top to bottom. When the globe valve is to be horizontally installed and the opening height of the valve disc is 25%~30% of the nominal diameter, the flow rate has reached *, indicating that the valve has reached the fully open position. So the fully open position of the shut-off valve should be determined by the stroke of the valve disc.
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