What condition would cause a resonating horn to sound on a Type 4 system?

In a Type 4 system, a resonating horn typically indicates an emergency stop condition. This safety feature is designed to alert personnel to potential hazards or critical situations that require immediate attention. When the system detects a situation that could lead to unsafe operating conditions, the resonating horn activates, signaling operators to take swift action to mitigate risk and ensure safety.

This functionality is critical in environments where timely interventions can prevent accidents or equipment damage. Understanding this response helps operators recognize the importance of monitoring alarms and responding appropriately to maintain safe operation standards. In contrast, the other options pertain to specific mechanical or environmental issues that may not necessarily trigger the emergency alarm system in the same way.