Why must moisture be removed from refrigerants? Select all key reasons relevant to system reliability and performance.
-
ATo avoid ice formation at the expansion valve or capillary
-
BTo prevent restriction to refrigerant flow and erratic operation
-
CTo reduce corrosion of ferrous components and chemical degradation with oil
-
DAll of these
-
EOnly to improve condenser effectiveness
Answer
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:
- System includes an expansion device (TXV/capillary), compressor, condenser, and evaporator.
- Refrigerant oil may react with acids formed in the presence of moisture.
- Low-temperature throttling points risk freezing water into ice.
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