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Advantages and Disadvantages of  Globe Valves

Globe Valve

Valve refers to a valve whose closure (disc) moves along the center line of the seat. According to the movement of the disc, the change of the seat opening is proportional to the disc travel. Because the stem opening or closing stroke of this kind of valve is relatively short, and has a very reliable cut-off function, and because the change of the seat opening is proportional to the disc travel, it is very suitable for flow regulation. Therefore, this type of valve is very flexible for cutting or regulating and throttling.

Bellow seal DIN Carbonsteel globe valve rising stem OY&S with lever DN80

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Flow direction of globe valve, down-to-up or up-to-down, Stem diameter?

Generally speaking, the flow of globe vales is from down to up. It means the medium will go through from disc downside then out by upside. Globe valves usually adopt compulsory sealed design, so close valve by offer pressure to disc against seat. So if you want to open valve, the globe valve disc must overcome resistance made by stem and packing friction, medium pressure will offer adverse pressure which help open valve. It means you can use less force than closing valve. So the stem diameter should be larger, to avoid stem bending fault.(depends on metal material physical performance of stem ). In recent years, there are more and more valve pressure seal, the medium through upper disc to down disc, so the close valve force is smaller than the open valve force, valve shaft diameter are allowed to be smaller.

Continue reading “Flow direction of globe valve, down-to-up or up-to-down, Stem diameter?”