Summary of globe valves
Globe valves are subject to compulsory sealed valve, so when the valve is closed pressure must be impressed to disc, prevent seal leakage. When the medium from below disc into valve, the operation is to overcome the resistance, which is stem and packing friction force produced by the medium pressure, the close force of the valve is larger than open force, so stem diameter should be large, otherwise it will happen stem bending fault. In recent years, since the valve seal appeared, the flow direction of medium is from upper disc into the body cavity, then above in medium pressure, close the valve force is smaller than open force of valve, the valve stem diameter can be reduced accordingly. At the same time, in effect, the form of the valve is strict. As is regulated in "thichem given", cut-off valve, using the top-down flow. Globe valve opens, disc height of open is 25% ~ 30% of nominal diameter, flow has reached the maximum, indicates the valve already in full open position. So the globe valve in full open position, should by disc trip to decide.
