Accident case analysis: one question per Monday (5). +3 wealth for participation, plus an additional 1-5 wealth for correct answers

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In the woodworking workshop of a furniture manufacturing company, there are processes such as sanding, polishing, and grinding of painted wooden items; the workshop also contains organic solvents and used paint buckets. The dust removal and purification system in the workshop uses a reverse-blow bag filter. The addition of new equipment and the expansion of production capacity have resulted in dust concentrations exceeding the allowed levels in the workshop. To control dust pollution in the workshop, the number of bag filters was increased from 4 to 8, and the concentration of wood dust in the workshop is now less than 10 mg/m3 after treatment. 　　At 9:20 on July 5, 2014, an explosion and fire occurred in dust collector No. 3 of the dust removal and purification system, which immediately triggered an explosion and fire in dust collector No. 4 as well, resulting in damage to some buildings and facilities within a 20-m radius of the site of the explosion. No injuries were reported as there was no one in the area where the explosion occurred. 　　Based on the above scenarios, answer the questions (multiple-choice).

1. According to the “Classification of Fires” (GB 4968–2008), classified by the combustion characteristics of substances, this accident falls under ( ).
A. Class A fire
B. Class B fire
C. Class C fire
D. Class D fire
E. Class E fire

2. To prevent such accidents from occurring again, the enterprise can adopt the following safety technical measures: ( )
A. Use anti-static filtering materials in the bag filter system.
B. Adopt an explosion-proof design for the dust removal chamber.
C. Conduct regular fire and explosion prevention drills.
D. Implement an approval system for hot work.
E. Increase the frequency of cleaning the filter bags.

3. According to the “Hygienic Standards for Industrial Enterprise Design” (GBZ 1–2010), which of the following statements regarding the design and installation requirements of the enterprise’s dust removal system are correct? ( )
A. Pipes for transporting dusty gases must be installed horizontally.
B. When horizontal pipes are used, it is not necessary to install cleaning holes.
C. Pipes for transporting dusty gases should be at an appropriate angle to the ground.
D. In dust removal systems dealing with explosive dusts and toxic gases, detection devices should be installed.
E. For testing purposes, testing holes should be provided at appropriate locations in the dust removal system.

4. According to the “Classification and Codes of Hazardous and Harmful Factors in Production Processes” (GB/T 13861–2009), the physical hazards and harmful factors present in this enterprise include: ( )
A. Wood dust
B. Noise generated during sanding, polishing, and grinding of painted wooden parts
C. Poor working conditions
D. High-temperature substances
E. Volatile organic gases from organic solvents used and paint in discarded paint cans

5. The direct causes of this accident may include: ( )
A. The dust concentration in the filter reached the explosive limit.
B. The temperature in the workshop was too high.
C. The flow rate of dusty gas in the dust removal pipes was too fast.
D. The dusty gas contained metal particles.
E. The humidity of the dusty gas in the filter was too high.

Answers:
1. A
2. A, B, E
3. C, D, E
4. A, B, C, D
5. A, C, D