There are many types of valve are available in the industries and with they have the different capability of the working as per the required application.
It is important to choose valve as per application, valve CV, types of valve trim, etc.
Here, I will cover one of the most commonly used sliding stem globe control valves. Due to it has a shape like a globe it is known as a globe valve.
The globe valve restricts the flow of the fluid by changing the distance between valve pug and seat.
A seat can be of the welded or threaded type, totally based on the amount of the temperature and pressure.
Due to globe valve has throttling capability is used to throttle flowing fluid.
Above is cut view section of globe valve. This is a single port globe valve because it has only one plug is there to control the flow of the fluid.
Also, you can see that the plug valve plug is guided by a stem that's why this type of valve is known as a stem guided valve.
Below figure is of the port guided valve. The plug has totally different shape thus seat here guide the plug to keep the seat and plug always aligned.
In the below figure you can see double port type globe valve. Here to throttle ot to control the flow of the flowing fluid to plug is used.
Below is cage guided globe valve. As you can see that in the cage it has a gap and inside that there is plug which moves up and down thus allow fluid to guide through that cage reduce pressure drop which means reducing chances of cavitation.
Advantage :
1. In cage guided valve you can easily change characteristics of valve by simply replacing cage of different shape or gap.
2. Easier actuation
Disadvantage :
1. Nearly impossible of tightly shut off for both cage guided and double port type globe valve.
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