When does the Audi-Larm ring on the SCBA?

The Audi-Larm ring on the Self-Contained Breathing Apparatus (SCBA) is designed as an audible alert for the wearer regarding the remaining air supply. It specifically activates when there is approximately 25% of the air left in the cylinder. This feature serves as a critical safety mechanism, allowing the user to be aware of their air supply status and to effectively plan for a safe exit from the hazardous environment.

This timing is crucial because it provides a buffer for the wearer to prioritize their exit before the air supply is completely depleted. The other options do not align with the standard operational protocols for SCBA devices, as they do not represent the correct safety measures or indicators for air consumption. The 25% alert system is widely recognized in fire service and emergency response training to ensure that personnel maintain situational awareness and manage their breathing apparatus effectively.