New Mexico Pipe Fitter Journeyman (JPF) Practice Exam

Which valve type is best suited for quick shut-off applications?

1. Globe valve

2. Butterfly valve

3. Check valve

4. Ball valve

The correct answer is: Ball valve

The ball valve is best suited for quick shut-off applications due to its design and operational characteristics. This type of valve features a spherical disc, or ball, that rotates within the valve body. When the ball is turned a quarter turn, it aligns its opening with the flow path, allowing fluid to pass through. Conversely, when the ball is turned 90 degrees to the flow path, the opening is effectively sealed, stopping the flow almost instantly. This rapid operation is advantageous in applications where immediate control of the fluid flow is essential, such as in emergency shutdown situations. The sealing capability of ball valves also ensures a tight shut-off, minimizing the risk of leakage when the valve is in the closed position. In contrast, other valve types have slower or less efficient operation for shut-off purposes. For example, globe valves require multiple turns to fully open or close, which can delay shut-off. Butterfly valves, while suitable for quick operations, may not provide the same level of sealing as ball valves due to their disk design. Check valves allow flow in one direction and do not necessarily function as shut-off valves. Thus, for applications that require immediate and reliable closure, ball valves are the preferred choice.