A globe valve works by using a disk that moves perpendicularly to the valve seat to control the flow of fluid.
Here's a breakdown of the working principle:
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Flow Control: Globe valves are primarily designed to start, stop, and regulate fluid flow within a pipeline. They offer better throttling capability compared to other valve types like gate valves.
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Disk and Seat Arrangement: The valve contains a movable disk (sometimes referred to as a plug or ball) that is screwed onto the end of a stem. This disk is positioned directly in line with the valve seat. The seat is a stationary ring within the valve body.
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Opening and Closing:
- To Open: Turning the valve handle rotates the stem. This rotational motion is converted into linear motion, raising the disk away from the seat. This creates an opening for the fluid to flow through the valve. The further the disk is lifted, the greater the flow rate.
- To Close: Turning the handle in the opposite direction rotates the stem, lowering the disk onto the seat. When the disk is fully seated, it creates a tight seal, stopping the flow of fluid.
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Fluid Flow Path: The fluid enters the valve body, flows upwards through the opening around the disk and seat, and then exits the valve. This flow path creates a higher pressure drop compared to straight-through valves like gate valves. This pressure drop is a characteristic of globe valves and contributes to their throttling capability.
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Throttling Capability: The ability to gradually adjust the disk's position relative to the seat allows precise control over the flow rate. This is why globe valves are commonly used in applications where accurate flow regulation is required.
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Maintenance: Globe valves typically require more maintenance than gate valves because the seat can become worn or damaged due to the constant impingement of fluid on the disk and seat during throttling.
In summary, a globe valve controls flow by moving a disk perpendicularly to a valve seat. This vertical movement either opens a pathway for fluid to flow through, or seals the opening to stop the flow, enabling precise flow regulation.
