You must have observed that Low inlet and high outlet are typically employed throughout the design and installation phase of globe valves, meaning that the globe valve flows from below the valve flap to above the valve flap. The question remains as to why this method is used so prominently.
In this article, we will be discussing bout the mechanism behind the working and installation of globe valves.
What is a globe valve?
Before knowing about the heavier workings of the valves, let us first understand the basic structure and function of globe valves.
The main purposes of a globe valve, a type of linear motion valve, are to stop, start, and regulate flow. A moveable disc and a fixed ring seat in a spherical body make up a globe valve. A globe valve’s seat lies in the middle of the pipe and runs parallel to it; the disc covers the opening in the seat. When the handwheel is turned manually or by an actuator the flow is entirely halted when the globe valve disc contacts the seat ring. However, as soon as the disc is raised, the flow starts because the upward motion of the disc makes room for the fluid.
Reasons for low inlet and high outlet
The major reason globe valves are constructed in such a way is that the low intake and high outlet of globe valves lower flow resistance and require less effort to open the valve. The padding between the valve casing and bonnet and the stuffing around the valve stem is also not stressed when the valve is closed, which means they won’t be adversely affected by medium pressure and temperature for a long time, extending their useful lives and lowering the likelihood of leaks. Additionally, when the valve is closed, the stuffing can be added or replaced, making maintenance easy.
Although this construction is not followed through all the globe valves, these are some exceptional cases.
Cases of high inlet and low outlet
Larger than 100mm diameter for high-pressure globe valves
Medium seal pressure helps to ensure proper sealing as the large diameter of the globe valve results in poor sealing performance.
Second globe valve in the series
The secondary valve installation direction must be “inlet high and outlet low” to prevent the padding of the second valve casing and bonnet and the stuffing around the valve stem from being adversely affected by medium and temperature to prevent the padding within the second valve casing and bonnet and the stuffing around the valve stem from being adversely affected by medium and temperature for an extended period of time.
Valves used for boiler start-up
Boiler exhaust and vent globe valves are only utilised during boiler starting and water supply, and despite their infrequent opening and shutting, the working medium loss is frequently brought on by shoddy sealing. Therefore, to increase tightness, some electric power plants build these globe valves in an inlet high and outlet low manner.
Conclusion
In conclusion, the construction and instalment technique of a globe valve depends on its application. If you wish to learn more about valves before applying them in your house, contact Obaid Masood, we are always happy to help you.