A cone valve has a moveable internal part that is cone shaped and is opened when the rotating ______ is turned through an angle of 90 degrees so fluid can pass through a machined port

• A. plug
• B. stem
• C. rotator
• D. knob

Answer: (A)

In a cone valve, the moving internal piece that actually creates or unblocks the flow is the cone-shaped plug. When you rotate the valve through about 90 degrees, the plug turns so its bore aligns with the machined port, letting fluid pass. The stem, knob, or other terms describe the parts used to make that rotation happen, but they are not the cone-shaped moving piece itself. That cone-shaped component is the plug, making it the correct term here.