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Monitoring practice questions

25 questions from the hazwoper 40-hour practice test.

Monitoring practice test

10 questions, graded as you go, with the reason for every answer. No sign-up.

What this covers

Sample questions

Below what oxygen concentration does OSHA consider an atmosphere oxygen deficient?

  1. 20.9%
  2. 18.0%
  3. 16.0%
  4. 19.5%
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D. 19.5%

An atmosphere with less than 19.5 percent oxygen by volume is oxygen deficient. Normal air is 20.9 percent, so that figure is the starting point, not the limit.

Reference: 29 CFR 1910.134(b); 29 CFR 1910.146(b)

A meter shows 24.5% oxygen inside a tank where an oxygen hose was left leaking. What is the main added danger?

  1. Workers will pass out from too much oxygen
  2. Materials ignite more easily and burn faster
  3. The gas meter's toxic sensors will stop working
  4. Flammable vapors become too rich to ignite
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B. Materials ignite more easily and burn faster

Above 23.5 percent the atmosphere is oxygen enriched, and clothing, oil and other combustibles catch fire more readily and burn violently. Extra oxygen does not make vapors too rich; it widens the fire hazard.

Reference: 29 CFR 1910.146(b), hazardous atmosphere

When testing an unknown atmosphere, such as a confined space, in what order should the hazards be checked?

  1. Toxic gases and vapors, then oxygen, then flammable gases and vapors
  2. Flammable gases and vapors, then toxic gases and vapors, then oxygen
  3. Oxygen, then flammable gases and vapors, then toxic gases and vapors
  4. Toxic gases and vapors, then flammable gases and vapors, then oxygen
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C. Oxygen, then flammable gases and vapors, then toxic gases and vapors

Oxygen is tested first, then combustible gases, then toxics. Starting with toxics seems natural because they feel most dangerous, but the combustible reading cannot be trusted until the oxygen level is known.

Reference: 29 CFR 1910.146(c)(5)(ii)(C) and Appendix B

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