What do water gongs or water motor gongs indicate?

Water gongs or water motor gongs are devices that signal when water is flowing through a fire protection system, such as a sprinkler system. Their primary function is to serve as local alarms that alert personnel to the presence of water flow, which is often indicative of an activated sprinkler head or another issue requiring immediate attention. This auditory signal is crucial in fire scenarios, as it informs facility staff and firefighters about the operational status of the water-based fire suppression system, enabling appropriate responses to emerging situations.

The other options do not accurately describe the function of water gongs. For instance, while system status is important, it encompasses a broader range of indicators beyond just what a water gong provides. Temperature fluctuations relate more to heat detection systems, and gas leakage alerts would involve different types of detection equipment entirely. Thus, focusing specifically on the role of water gongs leads directly to their identification as local alarms driven by water flow.