MCC-NH Gas Fitters Practice Exam

During a leak test, which gas is preferred for maintaining safety?

1. Nitrogen

2. Carbon monoxide

3. Combustible gas

4. Argon

The correct answer is: Combustible gas

The preferred gas for maintaining safety during a leak test is nitrogen. When performing leak tests, the goal is to detect leaks without presenting an ignition hazard. Nitrogen is an inert gas that is safe to use as it does not support combustion and does not pose any toxicity concerns. Using nitrogen allows gas fitters to safely pressurize the system and check for leaks without the risk of igniting any combustible mixtures. On the other hand, gases like carbon monoxide and combustible gases can create dangerous and potentially explosive environments, making them unsuitable for leak detection purposes. Argon, while also an inert gas, is not typically the first choice for leak testing due to its cost and lower availability compared to nitrogen. Therefore, selecting nitrogen for leak tests enhances safety by minimizing risks associated with flammable or toxic gases.