Question 32 QMED03 - Oiler

The Correct Answer is A **Explanation for Option A (R-12):** R-134a (1,1,1,2-tetrafluoroethane) was specifically developed as a non-ozone-depleting alternative to R-12 (dichlorodifluoromethane). R-12, a chlorofluorocarbon (CFC), was phased out globally under the Montreal Protocol because of its high ozone depletion potential (ODP). R-134a became the primary replacement in many applications, especially mobile air conditioning (MAC) and medium-temperature commercial refrigeration, often requiring minimal system changes compared to other alternatives. **Why the other options are incorrect:** * **B) R-22:** R-22 (chlorodifluoromethane) is a hydrochlorofluorocarbon (HCFC) and is being phased out primarily due to its significant global warming potential (GWP) and moderate ODP. While R-134a is used in some R-22 applications, the more common long-term replacements for R-22 in many air conditioning and heat pump systems are R-410A, R-32, or sometimes R-407C. R-134a is not generally considered the direct replacement across all typical R-22 equipment. * **C) R-11:** R-11 (trichlorofluoromethane) was primarily used in large centrifugal chillers (low-pressure systems). Its common replacement refrigerants were R-123 or R-500, not R-134a, which operates at much higher pressures suitable for different system designs. * **D) R-123:** R-123 (2,2-dichloro-1,1,1-trifluoroethane) is itself the common replacement for R-11 in low-pressure chiller systems. Therefore, R-134a would not typically be used as a replacement for R-123, as they serve different pressure and temperature applications.