What can be used to flush a refrigeration system after the refrigerant has been recovered?

• A. Water
• B. Compressed air
• C. Nitrogen
• D. Freon

Answer: (C)

Using nitrogen to flush a refrigeration system after the refrigerant has been recovered is an effective method because nitrogen is an inert gas that helps to purge the system of contaminants without introducing moisture or other harmful substances. When nitrogen gas is introduced into the system, it can effectively carry away oils, debris, and any residual refrigerant left in the lines. This is particularly important to maintain the efficiency and longevity of the system, as contamination can lead to operational issues.

In contrast, using water or compressed air can introduce moisture, which is detrimental to the system because moisture can lead to corrosion and the formation of acids. Water is not suitable for flushing because it does not mix well with refrigerants and can also cause rust in the components. Compressed air, while capable of clearing out some particulates, can still carry moisture along with it, potentially causing damage to the internal components of the refrigeration system. Using Freon again is not practical or effective, as it would simply reintroduce the same substance into the system without properly cleaning it.

Therefore, nitrogen is the best choice for flushing because it safely and efficiently cleans the system without the risks associated with moisture or oil contamination.