Question 50 QMED04 - Boiler Technician-Watertender

The Correct Answer is D **Explanation for Option D (Correct Answer):** Option D is correct because the primary safety advantage of using a **positive pressure** Self-Contained Breathing Apparatus (SCBA) in an Immediately Dangerous to Life or Health (IDLH) atmosphere is the mechanism of protection provided by the positive pressure itself. The regulator is designed to maintain a pressure inside the facepiece that is slightly higher than the ambient atmospheric pressure. If the seal of the facepiece is compromised (e.g., due to a minor shift, facial hair, or a faulty gasket), the positive internal pressure forces clean air *out* of the facepiece rather than allowing contaminated (IDLH) air to be drawn *in*. This safety margin is crucial for protecting the wearer in the most hazardous environments. **Explanation for Incorrect Options:** * **A) The equipment used is lightweight and easy to wear by reducing physical strain on the wearer.** While manufacturers strive to make SCBAs lighter, they are still relatively heavy (often 25-35 lbs or more) compared to non-respiratory PPE. Weight reduction is a desirable feature, but it is not the **particular advantage** relating to the fundamental protective function of the positive pressure design. * **B) The equipment is compact and the wearer can work in confined spaces without difficulty.** SCBAs, due to the bulk of the cylinder and harness, significantly increase the profile of the wearer, making them less compact than air-purifying respirators. Working in confined spaces is often difficult *because* of the size of the SCBA, making this statement inaccurate as a general advantage. * **C) The average operating time for most air cylinders is over an hour.** The vast majority of commonly used industrial and firefighting SCBAs (30-minute rated cylinders) typically offer an *actual* working time (under high exertion) closer to 15-25 minutes. Even larger cylinders (45-minute or 60-minute rated) rarely provide over an hour of working time due to safety margins and high consumption rates. Therefore, this statement about operating time is generally inaccurate.