The opening and closing component of the globe valve is a plug-shaped flap having a flat or conical surface, and the flap moves linearly along the centerline of the fluid. The movement of the valve stem is in the form of a lifting rod (the valve stem is lifted and lowered, the hand wheel does not move up and down), and the lifting rotary rod type (the hand wheel and the valve stem rotation) are lifted and lowered together, and the nut is fixed on the valve body). The globe valve is only suitable for full opening and full closing, not allowed to adjust and throttle.
The globe valve is a forced seal valve, so when the valve is closed, pressure must be applied to the valve flap to force the seal surface to leak. When the medium enters the valve from below the valve flap, the resistance overcome by the operating force is the friction of the flap and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve, so the diameter of the valve is large, otherwise the stem will bend.
In recent years, after the appearance of the self-sealing valve, the medium flow direction of the globe valve has changed from above the valve flap to the valve chamber. At this time, under the action of the medium pressure, the force for closing the valve is small, the force for opening the valve is large, and the diameter of the valve stem 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" limits the flow of the globevalve, all from top to bottom. When the globe valve is opened, the opening height of the flap is 25% to 30% of the nominal diameter, and the flow rate reaches the maximum value, indicating that the valve has reached the fully open position. Therefore, the fully open position of the globe valve should be determined by the stroke of the flap. The globe valve has the following advantages: simple structure, convenient manufacturing and maintenance. Short working hours and short opening and closing times. The sealing performance is good, the friction between the sealing surfaces is small, and the service life is long.