A sulphur candle is used to test for which type of leaks?

A sulphur candle is specifically designed for detecting ammonia leaks. When the candle is burned, it produces a characteristic gas that will react with ammonia, leading to a noticeable color change or odor that indicates the presence of ammonia in the air. This property makes it an effective tool in environments where ammonia is used, such as in refrigeration systems that utilize ammonia as a refrigerant.

Understanding the specific application of the sulphur candle in leak detection highlights its role in identifying ammonia, which is crucial in many industrial settings that use refrigeration systems. The other options pertain to other types of gases or refrigerants, which the sulphur candle is not meant to detect, thus reinforcing its primary use for ammonia leaks.