When performing a leak test, what medium is commonly used?

The most commonly used medium for leak testing is soapy water or nitrogen. Soapy water is effective because it creates bubbles at the location of any leak when it is applied to the connection points or joints being tested. The bubbles indicate the presence of gas escaping, making it a straightforward and visual method for detecting leaks.

Nitrogen is also frequently used in the process, particularly in systems that can tolerate pressurized testing. It is an inert gas, meaning it will not react with other substances, and is safe to use in a variety of applications.

Using pure oxygen is not a suitable option for leak testing, as it poses safety risks, especially in the presence of combustible materials. Air alone lacks the visual indicators that soapy water provides, making it less effective for identifying leaks. Helium, while it is a sensitive tracer gas for detecting very small leaks, is not as commonly used in routine leak tests compared to the practicality and effectiveness of soapy water or nitrogen.