Which of the following indicates cavitation in a fire pump?

Cavitation in a fire pump is characterized by a rattling noise similar to pumping gravel. This sound occurs when vapor bubbles form in the pump due to local pressure dropping below the vapor pressure of the liquid. As these bubbles move to areas of higher pressure within the pump, they collapse violently, causing noise and potentially damaging the pump components. This phenomenon can lead to a decrease in pump performance and damage if not addressed, making it a critical issue for operators to recognize and respond to quickly.

The other options, while they may present configurations concerning the pump’s operation, do not accurately indicate cavitation. Continuous flow without interruption suggests that the pump is operating normally, without any irregularities like those indicating cavitation. A decrease in engine temperature generally implies a lower load or a more efficient coolant system, not cavitation. High pressure readings on the gauge could suggest effective pumping but do not imply the cavitation condition, as cavitation is typically associated with low pressure in certain areas of the pump. Recognizing the rattling noise is crucial for identifying cavitation and maintaining effective pump operations.