Which component of a positive pressure self-contained breathing apparatus controls air flow to the user?

• A. Mask
• B. Regulator
• C. Tank
• D. Valve

Answer: (B)

The component of a positive pressure self-contained breathing apparatus (SCBA) that controls air flow to the user is the regulator. The regulator is a critical part of the SCBA because it reduces the high-pressure air from the tank to a safe, breathable pressure and manages the flow of air based on the user's inhalation demand. When the user inhales, the regulator opens a valve to allow air to flow from the tank to the mask. This ensures that an adequate supply of air is provided as needed while maintaining a positive pressure within the mask, which helps to prevent contaminants from entering.

In contrast, the tank is primarily responsible for storing the compressed air; the mask is where the user receives the air and protects the face, while the valve generally refers to the mechanisms that open and close airflow but does not actively manage the pressure or flow rate in the same way the regulator does. Thus, the regulator is the key component that directly influences how much air the user receives.