Confined Space: Ventilation and purging

All 14 questions in this test

Every question and its answer choices. The correct answers and explanations appear when you take the test above.

1. Why is mechanical ventilation usually needed instead of relying on natural air currents?

   1. Mechanical fans always add oxygen-rich air from compressed tanks
   2. Fans make the space quieter so workers can talk better
   3. Natural air currents are usually unreliable and insufficient
   4. Natural air currents are banned by every province's law

2. Even with mechanical ventilation running, what can remain inside a confined space?

   1. Only harmless water vapour from the workers' breathing
   2. Pockets of toxic gas in areas the air does not reach
   3. Extra oxygen that is created by the fan's motor running
   4. Nothing at all; ventilation always removes every hazard

3. If mechanical ventilation is needed to keep the air safe, what else does Ontario require?

   1. A spare fan stored in the office down the hall
   2. A warning system and exit procedure for ventilation failure
   3. Nothing else, as long as the fan is fairly new
   4. A second attendant who stands inside the space with the workers

4. Where should air removed from a confined space be exhausted?

   1. Into the nearest office window
   2. Back into the same space again
   3. Away from workers outside the space
   4. Toward the attendant standing at the hatch

5. How should a ventilation-failure alarm ideally be triggered?

   1. By the attendant checking the fan's colour
   2. By a flow or pressure switch in the air stream
   3. By the fan motor's own power switch only
   4. By a kitchen timer that rings once every hour

6. In B.C., when must natural ventilation not be relied on?

   1. In a high hazard atmosphere
   2. In spaces painted white
   3. In any space that has a fixed ladder
   4. When the weather is sunny

7. What is the difference between purging and ventilating a confined space?

   1. Purging adds pure oxygen to the space; ventilating removes all of the oxygen
   2. Purging is done after the work ends; ventilating is only done before entry
   3. There is no difference; both words describe opening the hatch for a while
   4. Purging displaces contaminants; ventilating keeps fresh air flowing

8. Which gas must never be used to ventilate a confined space?

   1. Filtered fresh air
   2. Supplied breathing air
   3. Pure oxygen
   4. Clean outdoor air

9. In Ontario, when must a space with oxygen or toxic hazards be purged or ventilated?

   1. Only after the first worker inside reports feeling dizzy or ill
   2. Only at the end of the shift, before the space is closed
   3. Before entry, so acceptable levels last while workers are inside
   4. Only if a ministry inspector is present at the site

10. Why must ventilation continue while work is being done in the space?

    1. To dry the paint on the walls more quickly
    2. Work can create contaminants and conditions can change
    3. To keep the attendant cool while they wait outside the space
    4. Because fans must run to keep their warranty valid

11. Where should the fresh-air supply and the exhaust be placed?

    1. Both at the very bottom
    2. As far apart as possible
    3. Side by side at the hatch
    4. In the same small opening

12. Ventilation of a space is not practical for technical reasons. What must entrants use in Ontario?

    1. Only a paper dust mask, as long as they stay inside for under an hour
    2. Respiratory protection, rescue-locating equipment and other needed gear
    3. Only a radio, so that they can describe the smell to the attendant
    4. Nothing extra, since the space is exempt when fans cannot be used

13. Where should the use of mechanical ventilation be noted?

    1. On the entry permit
    2. On the fan's box
    3. In a personal diary
    4. Nowhere at all

14. In B.C., what does "clean respirable air" in a confined space contain?

    1. Any oxygen level, as long as it does not smell bad
    2. About 16 % oxygen and no carbon dioxide at all
    3. About 20.9 % oxygen and no measurable flammable gas
    4. About 25 % oxygen and a small amount of methane