The Work Principle of a Globe Valve

Author:     Published time:2017-09-11 14:00     Reading times:395    

Brief introduction of a globe valve:

 

Simply, the principle is that the stem force is used to impress the sealing surface to stop medium and adjust its speed. And make the sealing surface in disc joint contact tightly with another surface in seat under the stem pressure. The trim part of the globe valve is a cylindrical disc while sealing face is a flat or a cone. And the disc makes a straight movement along the central line in fluids. The globe valve has two types of movement, one is outside screw stem rising through hand-wheel type globe valve, another inside screw non-rising stem type globe valve. A globe valve is a forced seal valve, i.e. the valve must be applied to the pressure and make the disc not leak when the valve is closed.

 

The work principle of a global valve:


Let us suppose there is a pipe with a lid. When water flows from the bottom of pipe and flows out to nozzle, the lid is as a trim part of the globe valve. If you lift the lid up, water will flows away. When you cover it with your hand, the flow will stop. Thus, this is the principle of a globe valve.The stem’s rising and falling in a globe valve is made through rotary hand-wheel to make the disc displace, driving the valve disc to move along a line parallel to the flow of medium, with which the opening and closing are achieved.


A hand-wheel rotates in clockwise direction with medium under the disc, and the sealing force must be equal or greater than the the sum of the necessary specific pressure generated on the sealing surface and the upward acting force of the medium.

When a globe valve opens, it means the valve is opened fully if the open height of the disc is 25% - 30% of the nominal diameter. So the full open position should be determined by the disc’s stroke.

 

Attention:


1.A globe valve has direction when it is installed for its one-way flow.

2.The effect of a global valve is 0 or 1, i.e. blocked or passable. In other words, a global valve can only fully opens or closes. Adjustment and throttling is not to be recommended.


 Related recommendation:


ANSI WCB Globe Valve

API 6D Fire Safe Forged Ball Valve






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