What component moves inside the removable cage of a single seated balance valve?

In a single seated balance valve, the component that moves within the removable cage is the valve plug. The primary function of the valve plug is to modulate or stop the flow of fluid through the valve. As the plug moves up and down, it changes the opening size between the valve seat and the plug, which directly affects the flow rate.

This mechanism ensures that the valve can effectively control flow while providing a degree of balance against pressure fluctuations. The design is intended to enhance performance and provide stable operation, particularly in applications where precise flow regulation is critical. The removable cage allows for easy access to the plug for maintenance or replacement without the need to dismantle the entire valve assembly.

The valve seat, flow control ring, and piston serve different functions within other types of valve configurations or systems but do not describe the moving component within the single seated balance valve's cage. This clarity helps understand the essential role the valve plug plays in the operation of the valve.