To check a leak in an Ammonia piping system, what is typically used?

In an ammonia piping system, a sulfur stick or pH paper is commonly used to check for leaks. When ammonia is present, it can react with the chemicals in the sulfur stick, producing a distinct reaction that indicates the presence of ammonia. This reaction is due to ammonia's alkaline nature, which can affect the pH of substances. The use of pH paper can also indicate the presence of ammonia based on shifts in pH levels, allowing operators to detect leaks effectively.

The other methods listed are either less suitable or not specifically designed for ammonia detection. A halide torch is primarily used for detecting refrigerants rather than ammonia specifically. A black light is typically used for detecting fluorescent dyes and may not be effective for identifying ammonia leaks. Hence, the sulfur stick or pH paper is the preferred and most effective choice for this particular application in ammonia systems.