Question 63 CEL01 - Chief Engineer - Limited

The Correct Answer is B. **Explanation for Option B (Correct):** CFC (chlorofluorocarbon) and HCFC (hydrochlorofluorocarbon) refrigerants are primarily haloalkanes, which are chemical compounds significantly denser and heavier than normal atmospheric air (which is mostly nitrogen and oxygen). When these refrigerants leak into a confined space (like a basement, walk-in freezer, or low-lying area), they tend to accumulate near the floor because they are heavier than the surrounding air. This accumulation displaces the oxygen necessary for breathing, creating an oxygen-deficient atmosphere. Suffocation occurs not because the refrigerant is inherently toxic (though many are), but because the concentration of breathable oxygen drops below the level required to sustain life. **Explanation of Incorrect Options:** * **A) Refrigerants obnoxious odor prevents breathing.** While some refrigerants may have a slight odor, the odor itself does not physically prevent breathing. More importantly, many common refrigerants, including R-134a and R-22, are nearly odorless, yet they still pose a suffocation risk due to oxygen displacement. * **C) Refrigerants lighter than air will rise.** This is chemically incorrect for CFC and HCFC refrigerants. As explained above, they are significantly heavier than air and sink, posing the greatest suffocation risk in low areas. (Note: Only certain refrigerants like ammonia or R-717 are lighter than air.) * **D) Refrigerants contain an acidic substance.** Pure, unused CFC/HCFC refrigerants are generally neutral. They can potentially break down into acidic substances (like hydrochloric or hydrofluoric acid) if heated (e.g., exposed to a flame), which causes chemical burns or lung irritation, but this is a toxicity/corrosion hazard, not the primary cause of suffocation upon leakage. Suffocation is caused by simple oxygen displacement.