Which statement about open-circuit SCBA is accurate?

Which statement about open-circuit SCBA is accurate?

• A. Open-circuit vents used air to the environment; air is not recycled.
• B. Open-circuit recycles exhaled air.
• C. Open-circuit uses only ambient air without a cylinder.
• D. Open-circuit has no regulator.

Answer: (A)

Open-circuit SCBA delivers breathing air from a compressed-air cylinder through a regulator to the facepiece, providing a safe, inhalable pressure. The key feature is that the air you exhale is expelled to the surrounding environment, not recirculated back into the system. So the supply comes from the cylinder, and the used air is vented away. This single-pass design contrasts with rebreathers, which scrub and recycle exhaled air. That’s why this statement is the best fit: it highlights that air is vented to the environment and not recycled. The other ideas don’t match how open-circuit SCBA actually works: it does rely on a cylinder (not ambient air alone), it uses a regulator to control pressure and flow, and it does not recycle exhaled air.

Open-circuit SCBA delivers breathing air from a compressed-air cylinder through a regulator to the facepiece, providing a safe, inhalable pressure. The key feature is that the air you exhale is expelled to the surrounding environment, not recirculated back into the system. So the supply comes from the cylinder, and the used air is vented away. This single-pass design contrasts with rebreathers, which scrub and recycle exhaled air.

That’s why this statement is the best fit: it highlights that air is vented to the environment and not recycled. The other ideas don’t match how open-circuit SCBA actually works: it does rely on a cylinder (not ambient air alone), it uses a regulator to control pressure and flow, and it does not recycle exhaled air.