The low alarm of the self-contained breathing apparatus will sound when_____ of the cylinder's air supply is remaining.

• A. 15 percent of 150 liters
• B. 18 Percent or 200 liters
• C. 30 Percent or 750 liters
• D. 33 Percent or 792 Liters

Answer: (D)

The low-air alarm is designed to trigger when the firefighter has about one-third of the cylinder’s air remaining. This gives enough time to safely exit and complete a bailout or switch to another air source. In this scenario, a full cylinder contains about 2400 liters, so 33% of that is roughly 792 liters. That’s why the correct threshold is 33% or 792 liters—the alarm is meant to sound with enough remaining air to safely retreat. The other values do not match this standard threshold with the given cylinder capacity.