Globe, Rotary, and Butterfly Control Valves

Globe, Roary, and Butterfly Control Valves

Control valves are crucial components in industrial processes, used to regulate the flow of fluids. Different types of control valves offer specific advantages and are suitable for particular applications. Here's a comparison of globe style control valves, rotary control valves, and butterfly control valves:

Globe Style Control Valves

Design and Operation:
These have a linear motion and use a movable disk-type element and a stationary ring seat in a spherical body. The disk can be moved away from the seat (to open) or towards the seat (to close) to regulate the flow.

  • Precise control: They are well known for their accurate throttling capabilities.
  • Good shut-off capability.
  • Wide rangeability (the range of flow rates over which the valve can effectively control).
  • Higher pressure drop compared to other types of valves.
  • Bulky design and requires more space.
  • Suitable for most processes where precise control is needed.
  • Often used in extreme temperature and pressure applications.

Rotary Control Valves

Design and Operation:
These valves rotate a disk or ball, with or without a shaft, within the flow stream to control flow. Common examples include ball valves, v-notch ball valves, and eccentric disk valves.

  • Compact design.
  • Lower pressure drops compared to globe valves.
  • Quick response and faster actuation compared to globe valves.
  • Good rangeability.
  • Less precise control compared to globe valves in some applications.
  • Might not provide as tight shut-off as globe valves.
  • Suitable for applications where quick actuation or less pressure drop is crucial.
  • Often used for on/off services or in applications where the media might cause obstruction in other types of valves.

Butterfly Control Valves

Design and Operation:
Consists of a circular disc or plate built onto a rod. When the rod is turned, the disc turns at a right angle to the flow, acting like a dam to stop or start the flow.

  • Extremely compact design.
  • Economical, especially for larger sizes.
  • Low pressure drop.
  • Suitable for slurry applications or services with suspended particles.
  • Not as precise as globe valves for control.
  • Might not offer a tight shut-off in certain designs.
  • Rangeability is often less than globe or some rotary valves.
  • Used in cooling water systems, air/gas compressors, and industrial HVAC systems.
  • Suitable for applications where tight shut-off isn't critical and where space or cost is a concern.

In choosing the right control valve for a specific application, various factors need to be considered, including the nature of the media, the required flow rate, the allowable pressure drop, the need for tight shut-off, and the degree of control precision. Each type of valve has its own niche in industrial applications, and the selection often depends on trade-offs among these factors.

Classic Controls
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