Confined Space Training Certificate Confined Space Definition & Hazards 1 — Questions and Answers
Question 1: What is the legal definition of a confined space under the Confined Spaces Regulations 1997?
- Any place that is substantially enclosed and where there is a reasonably foreseeable specified risk (Correct answer)
- Any underground area that requires a ladder to enter
- Any room with only one exit
- Any area where two or more people cannot work simultaneously
Correct answer: Any place that is substantially enclosed and where there is a reasonably foreseeable specified risk
The Confined Spaces Regulations 1997 define a confined space as any place that is substantially enclosed and where there is a reasonably foreseeable specified risk of serious injury from hazardous substances or conditions.
Question 2: Which of the following is NOT listed as a specified risk under the Confined Spaces Regulations 1997?
- Slipping on a wet floor (Correct answer)
- Loss of consciousness due to oxygen deficiency
- Drowning in a free-flowing liquid
- Fire or explosion
Correct answer: Slipping on a wet floor
Slipping on a wet floor is a general workplace hazard, not a specified risk under the Confined Spaces Regulations 1997. Specified risks include oxygen deficiency, toxic atmosphere, drowning, fire/explosion, and loss of consciousness from heat.
Question 3: At what percentage of oxygen in the atmosphere is a confined space considered oxygen deficient?
- Below 19.5% (Correct answer)
- Below 21%
- Below 17%
- Below 15%
Correct answer: Below 19.5%
An atmosphere is considered oxygen deficient when it contains less than 19.5% oxygen. Normal atmospheric oxygen is approximately 20.9%. Below 19.5% can cause impaired judgement; below 16% can be fatal.
Question 4: Which gas is heavier than air and can accumulate at the bottom of a confined space?
- Carbon dioxide (Correct answer)
- Methane
- Hydrogen
- Ammonia
Correct answer: Carbon dioxide
Carbon dioxide (CO2) is heavier than air (density ratio approximately 1.52) and will sink and accumulate at the bottom of confined spaces such as pits, tanks, and cellars, displacing oxygen.
Question 5: What is engulfment in the context of confined space hazards?
- Being submerged or buried by a free-flowing solid or liquid material (Correct answer)
- Being overcome by toxic fumes
- Being trapped by a structural collapse
- Being unable to escape due to a locked exit
Correct answer: Being submerged or buried by a free-flowing solid or liquid material
Engulfment is the submersion or burial of a person by a free-flowing solid (such as grain or sand) or liquid, which can cause suffocation or crush injuries. It is a specified risk under the Confined Spaces Regulations 1997.
Question 6: A sewer is an example of a confined space because it is substantially enclosed and presents which specific hazard?
- Toxic atmosphere from hydrogen sulphide and methane (Correct answer)
- Extreme cold temperatures
- High voltage electricity
- Falling from height
Correct answer: Toxic atmosphere from hydrogen sulphide and methane
Sewers are classic confined spaces presenting toxic atmospheric hazards including hydrogen sulphide (H2S), which can be lethal at very low concentrations, and methane, which is both asphyxiating and flammable.
Confined Space Training Certificate Confined Space Definition & Hazards 1
What is the legal definition of a confined space under the Confined Spaces Regulations 1997?