Which valve is NOT part of a drainage system?

The globe valve is primarily designed for throttling flow and is typically used in applications where precise flow control is necessary. Closely associated with regulation, its structure features a spherical body with an internal baffle that creates resistance to flow. While globe valves can be used in various hydraulic systems, they are not generally utilized for drainage purposes, where quick opening and closing are more critical.

In a drainage system, the other valve types—ball valves, check valves, and butterfly valves—play different roles. Ball valves are known for their quick shut-off capability, making them suitable for controlling the flow in drainage applications. Check valves prevent backflow and maintain the direction of the fluid flow, which is essential for drainage systems to function properly. Butterfly valves are also employed for controlling flow and can facilitate faster operation and movement in larger pipes, making them advantageous in drainage scenarios.

Therefore, the globe valve's function and design do not align well with the requirements of a drainage system, making it the one that does not belong.