How can ammonia leaks in refrigeration systems be detected?

Ammonia leaks in refrigeration systems can be effectively detected by using a sulphur candle. This method is based on the chemical reaction that occurs when ammonia comes into contact with the combustion products of the sulphur candle. When ammonia is present, it can interact with the compounds released from the burning sulphur, producing a distinct color change or smell that indicates a leak.

While the other methods mentioned may have their own applications, they do not specifically target the detection of ammonia leaks as effectively as a sulphur candle. Using a pressure gauge is useful for monitoring the system's operation but does not provide direct evidence of leaks. Listening for hissing sounds may indicate a leak, but it is not a reliable detection method for small or hidden leaks. Applying soapy water can reveal leaks through the formation of bubbles, but this method is not as definitive or sensitive for identifying ammonia specifically compared to the reaction observed with a sulphur candle. Thus, the use of a sulphur candle stands out as a proven technique for detecting ammonia in refrigeration systems.