What type of valve includes features that indicate if it is open or closed?

An indicating valve is specifically designed with features that visually or audibly show the status of the valve, indicating whether it is open or closed. These features can include mechanical indicators or visual markers that provide immediate feedback to operators or maintenance personnel. This characteristic is crucial in fire protection systems, as it allows for quick assessment of the system's readiness and helps ensure that the proper flow of water is maintained in emergencies.

In contrast, other types of valves, such as check valves and pressure relief valves, do not possess this straightforward indication feature. Check valves are designed primarily to prevent backflow in a system and typically do not have an indication system for their open or closed status. Pressure relief valves serve to mitigate overpressure conditions and are generally designed to automatically open or close based on system pressure without providing a clear indication of position. Control valves regulate fluid flow in a system but might not have a clear visual signal regarding their open or closed states.

Therefore, the defining characteristic of an indicating valve is its ability to convey the operational status clearly and effectively, making it the correct choice in this context.