MCC-NH Gas Fitters Practice Exam

Why should a test medium not include oxygen?

1. It is expensive to use

2. It can pose an explosion hazard

3. It diffuses too quickly

4. It is not readily available

The correct answer is: It can pose an explosion hazard

A test medium should not include oxygen primarily because it can pose an explosion hazard. In environments where flammable gases are present, the presence of oxygen can significantly increase the risk of combustion or explosion. Oxygen supports combustion, meaning that if a leak were to occur, the combination of oxygen and a flammable gas could lead to a dangerous situation. Therefore, when conducting tests on gas systems, using a medium devoid of oxygen helps to mitigate these risks and ensures safety. While other choices mention considerations like cost, availability, and diffusion rates, these factors are less critical compared to the safety risks associated with having oxygen in the test medium. The controlling of explosion hazards is a fundamental practice in gas fitting and related industries, reinforcing why this particular aspect is prioritized.