What is an indication of leaking refrigerant in the primary piping?

The correct indication of leaking refrigerant in the primary piping is the presence of ammonia in the brine. In systems using ammonia as a refrigerant, any escape of ammonia into the brine solution would lead to a detectable increase in ammonia concentration. This is significant because ammonia is a toxic and corrosive substance, and its presence in areas where it should not be indicates that there is a leak in the system.

In contrast, the presence of rust on external surfaces may suggest corrosion but does not directly confirm a refrigerant leak. Unusual noises during operation can point to mechanical issues or malfunctions within the system, which are not specifically related to refrigerant leakage. Low-pressure readings on gauges can indicate a variety of issues, including low refrigerant levels due to various reasons not necessarily specific to leaks, such as improper system charge or system failure.

Understanding the specific characteristics of ammonia and its detection is crucial for maintaining safety and efficiency in refrigeration systems, making the identification of ammonia in brine a vital sign of leakage.