Which valve has a circular disk perpendicular to flow that can rotate at least 90 degrees and is commonly used in large diameter piping?

Which valve has a circular disk perpendicular to flow that can rotate at least 90 degrees and is commonly used in large diameter piping?

• A. Globe valve
• B. Needle valve
• C. Butterfly valve
• D. Check valve

Answer: (C)

This question hinges on how the valve’s disk is arranged and how it moves to open or close. A butterfly valve uses a circular disk mounted on a shaft that runs through the center of the valve. The disk sits in the flow and can rotate about that shaft a full quarter turn (90 degrees). When the disk is perpendicular to the flow, it blocks the passage; a 90-degree rotation brings the disk into alignment with the flow, allowing it to pass with minimal obstruction. This compact, lightweight design is especially advantageous for large-diameter piping, where a gate valve would be bulkier and heavier. In contrast, a globe valve achieves throttling with a plug that moves linearly against a seat, requiring more than a simple quarter-turn and often not suited for large diameters. A needle valve is designed for fine, precise control in small lines and uses a tapered needle, not a rotating disk. A check valve relies on flow to move a disk or flap to block backflow and isn’t operated by a 90-degree rotation to open. So the disk-on-a-shaft arrangement that rotates about 90 degrees and blocks flow when closed, while remaining compact for large pipes, points to the butterfly valve.

This question hinges on how the valve’s disk is arranged and how it moves to open or close. A butterfly valve uses a circular disk mounted on a shaft that runs through the center of the valve. The disk sits in the flow and can rotate about that shaft a full quarter turn (90 degrees). When the disk is perpendicular to the flow, it blocks the passage; a 90-degree rotation brings the disk into alignment with the flow, allowing it to pass with minimal obstruction. This compact, lightweight design is especially advantageous for large-diameter piping, where a gate valve would be bulkier and heavier.

In contrast, a globe valve achieves throttling with a plug that moves linearly against a seat, requiring more than a simple quarter-turn and often not suited for large diameters. A needle valve is designed for fine, precise control in small lines and uses a tapered needle, not a rotating disk. A check valve relies on flow to move a disk or flap to block backflow and isn’t operated by a 90-degree rotation to open.

So the disk-on-a-shaft arrangement that rotates about 90 degrees and blocks flow when closed, while remaining compact for large pipes, points to the butterfly valve.