Free practice quiz · 10 questions

Air Monitoring and Gas Detection Quiz

Answer every question, then press Check my answers to see your score and an explanation for each one. Study first with the guide: HAZWOPER Air Monitoring: Oxygen, LEL, Toxics and Direct-Reading Instruments.

1. Above what oxygen level is an atmosphere considered oxygen enriched?

Answer: 23.5%. Above 23.5% oxygen is enriched and increases fire risk.

2. What should you test first on initial entry?

Answer: Oxygen. Test oxygen first: low oxygen kills quickly and also affects combustible gas readings.

3. What does LEL stand for?

Answer: Lower explosive limit. The lower explosive limit is the lowest concentration of a gas in air that will ignite.

4. Which instrument does NOT respond well to methane?

Answer: PID. Methane's ionization potential is higher than standard PID lamp energies, so PIDs miss it. FIDs detect it.

5. A typical 4-gas meter measures:

Answer: O2, LEL, H2S and CO. Standard 4-gas meters measure oxygen, combustibles (LEL), hydrogen sulfide and carbon monoxide.

6. What is a bump test?

Answer: Exposing the meter to a known gas to check the sensors and alarms respond. A bump test is a functional check, usually done before each day's use.

7. Gases with a vapor density greater than 1 tend to:

Answer: Sink and collect in low areas. Heavier-than-air gases sink into trenches, pits and basements, so monitor low points.

8. Which gives a reading for one specific chemical?

Answer: Colorimetric detector tube. Colorimetric tubes are chemical-specific; PIDs and FIDs respond to many compounds.

9. A STEL is averaged over:

Answer: 15 minutes. A short-term exposure limit is a 15-minute time-weighted average.

10. Combustible gas readings are accurate only when:

Answer: Oxygen levels are normal. Catalytic LEL sensors need oxygen; in oxygen-deficient air they can read low.

More free HAZWOPER quizzes