Certified Pulmonary Function Technologist (CPFT) Practice Exam

For what gas is a thermal conductive gas analyzer used?

1. Oxygen

2. Nitrogen

3. Helium

4. Argon

The correct answer is: Helium

A thermal conductive gas analyzer is specifically designed to measure gases based on their thermal conductivity properties. Each gas has a unique ability to conduct heat, which allows for differentiation when they are mixed in a sample. Helium has significantly higher thermal conductivity compared to other common gases like oxygen, nitrogen, and argon. This enhanced thermal conductivity makes helium easily detectable by thermal conductive gas analyzers, which rely on the degree of heat transfer to determine concentration levels. In contrast, while oxygen and nitrogen do have measurable thermal conductivity, they do not offer the distinct contrast that helium does in these applications. Argon similarly does not have the high thermal conductivity necessary to make it suitable for detection with this type of analyzer. Therefore, the choice of helium as the gas for which a thermal conductive gas analyzer is used is valid because it optimally aligns with the principles behind the mechanism of this type of instrumentation.