Quiz on Carbon Dioxide Properties as a Fire-Extinguishing Agent
Carbon dioxide (CO₂) is an effective fire-extinguishing agent due to its various properties. It is non-combustible, does not react with most substances, and provides its own pressure for discharge. As a gas, CO₂ can easily penetrate fire areas and is capable of suppressing flames by displacing oxygen. It is safe to use on energized electrical equipment as it does not conduct electricity. Additionally, it leaves no residue, eliminating the need for cleanup. CO₂ has unique thermodynamic properties. At room temperature and pressure, it is a colorless and odorless gas. It can be easily liquefied by compressing and cooling, and further compression and cooling can turn it into a solid. Its pressure and temperature influence its state (gas, liquid, or solid), with transitions occurring at critical points, including the triple point.
Multiple-Choice Questions
1. Which of the following properties makes carbon dioxide an effective fire-extinguishing agent?
- a) It reacts with most substances.
- b) It can conduct electricity and is safe for electrical equipment.
- c) It leaves no residue after use.
- d) It requires an external source of pressure for discharge.
Answer: c) It leaves no residue after use.
2. What state does carbon dioxide exist in above the critical temperature of 87.8°F (31°C)?
- a) Solid
- b) Liquid
- c) Gas
- d) Gas and liquid
Answer: c) Gas
3. At what temperature does carbon dioxide exist in all three phases (gas, liquid, and solid) simultaneously?
- a) -69.9°F (-57°C)
- b) 0°F (-18°C)
- c) 87.8°F (31°C)
- d) 75 psia (517 kPa)
Answer: a) -69.9°F (-57°C)
4. What happens to liquid carbon dioxide when it is discharged into the atmosphere?
- a) It remains as a liquid and evaporates slowly.
- b) It instantly flashes to vapor and a portion becomes dry ice (snow).
- c) It freezes into solid dry ice immediately.
- d) It solidifies into a compact block.
Answer: b) It instantly flashes to vapor and a portion becomes dry ice (snow).
5. What is a critical safety measure when discharging carbon dioxide?
- a) The discharge nozzles should be insulated.
- b) The nozzles must be grounded to prevent static electricity buildup.
- c) The system should be pressurized with air.
- d) Discharge should be performed in an open area to avoid contamination.
Answer: b) The nozzles must be grounded to prevent static electricity buildup.
6. What happens to the density of carbon dioxide vapor when it is discharged at very low temperatures?
- a) It becomes lighter than air and rises.
- b) It maintains the same density as the surrounding air.
- c) It becomes much denser than air and sinks.
- d) It disperses evenly in the atmosphere.
Answer: c) It becomes much denser than air and sinks.
7. What is the standard storage temperature for low-pressure carbon dioxide containers?
- a) 87.8°F (31°C)
- b) 0°F (-18°C)
- c) -69.9°F (-57°C)
- d) 70°F (21°C)
Answer: b) 0°F (-18°C)
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