A valve that requires five 360° turns of the hand wheel to change from fully open to fully closed is classified as what type of valve?

A valve that requires five complete turns of the hand wheel to transition from fully open to fully closed is classified as a slow opening valve. This classification arises from the operational characteristics and design of the valve.

In contrast to quick opening valves, which can fully open or close with minimal turns of the hand wheel—ideally allowing for rapid changes in flow—a slow opening valve prevents abrupt changes in pressure and flow rate. This aspect is crucial in applications where gradual adjustments are necessary to avoid system shocks or fluctuations, which could lead to equipment stress or failures.

In the case of an on/off valve, it is typically designed for quick operation, requiring fewer turns to switch between its two positions. A butterfly valve, known for its simple disc design, generally allows for quicker adjustments as well, resembling the functionality of an on/off valve.

Thus, given the valve's requirement of multiple turns to operate effectively, it rightly falls under the slow opening valve classification, signifying its design for gradual flow control rather than immediate changes.