Which of the following is a major component of a typical open-circuit SCBA?

• A. Facepiece
• B. Regulator/Purge
• C. High-pressure cylinder
• D. All of the above

Answer: (D)

The main idea is that an open-circuit SCBA needs three essential parts to deliver breathable air: a stored air supply, a way to control and deliver that air, and the interface you breathe from. The high-pressure cylinder stores the compressed air you inhale. The regulator reduces that high cylinder pressure to a safe, workable level and controls the flow so air is available on demand; the purge function within that system helps flush the line and ensure clean air delivery when you don’t want stale or contaminated air in the line. The facepiece is the actual breathing interface you wear and seals to your face so you don’t draw in contaminated air from the surroundings. Remove any one of these, and the unit can’t supply breathable air properly. That’s why all of the above are considered major components.