Globe valves are a type of control valve used to stop, start and regulate the flow of media through a pipe. From the outside, they have a spherical body design; inside, a plug-like disc sits on the end of a threaded rotating stem, which raises and lowers to control media flow. Globe valves are part of the linear motion valve family, which means that the valve mechanism moves along a straight line.
Globe valves provide a tight seal with low chances of leakage, which is why they are a common choice in high-pressure, industrial piping systems.
Globe valves are designed so that the media flowing through them does not travel in a straight line. Rather than encountering a perpendicular blockage at the valve, the media must take a slight vertical detour up through the valve cavity, where it meets the plug disc. As the valve stem is turned via wheel and raises to allow media through, the disc moves parallel to the flow. The position of the stem tells operators whether the valve is open or closed.
This vertical movement is what enables the globe valve to regulate media flow, rather than simply stopping or starting it. The distance between the disc and the seat determines the flow rate: the farther apart the disc and seat are, the higher the volume of media passing through. Globe valves are ideal for throttling, or regulating the flow of media while in a partially open position, and make starting and stopping flow less abrupt which can help prevent water hammer.
Because their design forces media to change direction (horizontal to vertical), globe valves create a high-pressure drop. They are best used in applications that require only unidirectional flow, where massive changes in pressure are not an issue and where safety and leakage are primary concerns. Globe valves are often found in piping systems that transport corrosive, viscous, highly pressurized or extremely hot or cold media.
Most of the working parts of a globe valve lie inside the cavity, and access to the internal components is through the top; this is known as top-entry design.
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