Question 924 Deck Safety

The correct answer is A) About 4-5 minutes. When the alarm bell sounds on a positive-pressure, self-contained breathing apparatus (SCBA), it indicates that the user's reserve air supply is low, typically around 25% of the total capacity. Regulations require SCBA units to have a minimum reserve air supply of 4-5 minutes to allow the user to safely exit the hazardous environment. The other options are incorrect because they do not align with the standard reserve air supply requirements for SCBA units.