Question 44 QMED03 - Oiler

The Correct Answer is A. **Explanation for why Option A is correct:** The term "hygroscopic" specifically means a substance readily attracts and holds water molecules from the surrounding environment (like the air). Lubricants used in refrigeration (especially those used with HFCs and POE oils) are often highly hygroscopic. This characteristic means they have a high affinity for moisture, which is extremely detrimental to the refrigeration system (as moisture can lead to corrosion, acid formation, and system freeze-ups). Therefore, a hygroscopic lubricant **must** be kept in a sealed, dry container to prevent moisture absorption prior to use. **Explanation for why the other options are incorrect:** * **B) decreasing in viscosity at low temperatures:** While the viscosity of any oil changes with temperature, "hygroscopic" refers only to moisture affinity, not its viscosity-temperature relationship. Furthermore, a significant decrease in viscosity at low temperatures would generally be considered a negative characteristic for a lubricant, not a definition of hygroscopic. * **C) losing its lubrication qualities at higher temperatures:** This describes thermal breakdown or poor thermal stability of the oil. While all oils have an upper temperature limit, "hygroscopic" refers only to moisture affinity, not its resistance to heat. * **D) being highly toxic:** Toxicity is a chemical safety property, completely unrelated to the physical property of being hygroscopic (water-attracting). Refrigeration lubricants are formulated to be low in toxicity, although they must still be handled safely.