Difficulty: Easy
Correct Answer: All of these
Explanation:
Introduction / Context:
Moisture is a critical contaminant in refrigeration and air-conditioning systems. Even tiny amounts can create blockages, degrade materials, and shorten compressor life.
Given Data / Assumptions:
Concept / Approach:
At the expansion device, temperatures can drop below 0°C. Any dissolved water can precipitate as ice, causing blockage. Moisture also participates in hydrolysis reactions forming acids (especially with halocarbon refrigerants), leading to corrosion and insulation breakdown in hermetic motors. Desiccant driers are therefore standard.
Step-by-Step Solution:
Identify freezing risk: water → ice at throttling → blockage.Recognize flow restriction: intermittent icing produces erratic pressures and poor cooling.Consider materials: acids from moisture cause corrosion and oil degradation.Conclusion: all listed reasons apply.
Verification / Alternative check:
Service practices mandate evacuation (vacuum) and filter-driers to control moisture levels to a few ppm.
Why Other Options Are Wrong:
(E) focuses only on the condenser and ignores major risks at the expansion device and compressor.
Common Pitfalls:
Assuming sight-glass “no bubbles” implies no moisture; proper indicators or laboratory tests are needed.
Final Answer:
All of these
Discussion & Comments