Ignite Success: Ace the 2026 MCC-NH Gas Fitters Exam!

The preferred gas for maintaining safety during a leak test is nitrogen. Nitrogen is an inert gas that is commonly used in leak testing because it poses no risk of combustion or toxic exposure. It is non-flammable, which means that in the event of a leak, there is no danger of creating a fire or explosion, making the environment safe for testing.

Using nitrogen allows gas fitters to pressure-test systems without introducing hazardous gases. This safety measure is crucial in preventing any accidents that could arise from leaks involving combustible or toxic gases, which can create significant health and safety risks.

In contrast, other gases listed do not provide the same level of safety during leak tests. Carbon monoxide is hazardous and poses severe health risks due to its toxicity. Combustible gas, as the name suggests, can ignite and lead to dangerous situations if a leak occurs, while argon, while inert, is less commonly used specifically for leak testing as nitrogen is more readily available and cost-effective. Thus, the choice of nitrogen underscores a commitment to ensuring safe testing procedures in gas fitting practices.