When will the low air alarm sound on a SCBA?

The low air alarm on a Self-Contained Breathing Apparatus (SCBA) is designed to activate when one-quarter of the air supply remains in the tank. This safety feature is crucial as it alerts the firefighter to the diminishing air supply, allowing them to make timely decisions about exiting an area or seeking a refill.

The choice of activating at one-quarter full ensures that there is adequate air supply for the firefighter to exit safely, considering that the situation may become more hazardous as time passes. Since the primary concern for firefighters is safety and maintaining the ability to breathe while performing their tasks, this early warning is a vital component of operational safety.

Other options do not provide sufficient early warning. For instance, if the alarm were to sound at three-quarters of the air remaining or half, firefighters may find themselves in a precarious situation where they have less time to respond to air supply needs. Furthermore, sounding the alarm when the tank is empty would offer no assistance, as it would be too late to take necessary actions to ensure safety.