NFPA 650 Combustible Dust in Process
Industries Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
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1. What is the primary hazard associated with combustible dust in
industrial facilities?
A. Electrical shock
B. Dust deflagration or explosion
C. Noise exposure
D. Radiation release
Answer: B
Rationale: Combustible dust can ignite and rapidly burn, causing
deflagrations or explosions when suspended in air within confined
spaces.
2. Which element is NOT part of the dust explosion pentagon?
A. Fuel
B. Oxygen
C. Confinement
, D. Refrigeration
Answer: D
Rationale: The explosion pentagon includes fuel, oxygen, ignition
source, dispersion, and confinement; refrigeration is unrelated.
3. A dust hazard analysis (DHA) is primarily used to:
A. Calculate payroll
B. Identify and evaluate combustible dust risks
C. Design office furniture
D. Track attendance
Answer: B
Rationale: NFPA 650 requires DHAs to assess processes and
identify potential combustible dust hazards and controls.
4. Which material is most likely to produce combustible dust?
A. Sand
B. Aluminum powder
C. Water vapor
D. Solid steel beams
Answer: B
Rationale: Fine metal powders such as aluminum can be highly
combustible under the right conditions.
,5. Minimum ignition energy refers to:
A. Energy needed to cool dust
B. Lowest energy capable of igniting dust
C. Energy needed to ventilate a room
D. Energy for static grounding
Answer: B
Rationale: Minimum ignition energy determines how easily a dust
cloud can ignite from sparks or static discharge.
6. Housekeeping is critical because it:
A. Improves decoration
B. Prevents accumulation of hazardous dust layers
C. Reduces electricity bills
D. Replaces engineering controls
Answer: B
Rationale: Proper cleaning reduces dust buildup that could
become airborne and ignite.
7. Which device is used to control explosion pressure?
A. Explosion vent
B. Water hose reel
C. Smoke detector
D. Thermostat
, Answer: A
Rationale: Explosion vents relieve pressure to minimize structural
damage during a deflagration.
8. What is a primary ignition source in dust environments?
A. Paperwork
B. Static electricity
C. Office lighting schedules
D. Nonconductive flooring alone
Answer: B
Rationale: Static discharge is a common ignition source if
grounding and bonding are inadequate.
9. Dust collectors should be located:
A. Inside confined offices
B. Outdoors or in protected areas when feasible
C. Next to break rooms
D. Under staircases
Answer: B
Rationale: External placement reduces the risk to personnel and
structures if an explosion occurs.
10. Which control reduces oxygen concentration?
A. Inerting
Industries Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. What is the primary hazard associated with combustible dust in
industrial facilities?
A. Electrical shock
B. Dust deflagration or explosion
C. Noise exposure
D. Radiation release
Answer: B
Rationale: Combustible dust can ignite and rapidly burn, causing
deflagrations or explosions when suspended in air within confined
spaces.
2. Which element is NOT part of the dust explosion pentagon?
A. Fuel
B. Oxygen
C. Confinement
, D. Refrigeration
Answer: D
Rationale: The explosion pentagon includes fuel, oxygen, ignition
source, dispersion, and confinement; refrigeration is unrelated.
3. A dust hazard analysis (DHA) is primarily used to:
A. Calculate payroll
B. Identify and evaluate combustible dust risks
C. Design office furniture
D. Track attendance
Answer: B
Rationale: NFPA 650 requires DHAs to assess processes and
identify potential combustible dust hazards and controls.
4. Which material is most likely to produce combustible dust?
A. Sand
B. Aluminum powder
C. Water vapor
D. Solid steel beams
Answer: B
Rationale: Fine metal powders such as aluminum can be highly
combustible under the right conditions.
,5. Minimum ignition energy refers to:
A. Energy needed to cool dust
B. Lowest energy capable of igniting dust
C. Energy needed to ventilate a room
D. Energy for static grounding
Answer: B
Rationale: Minimum ignition energy determines how easily a dust
cloud can ignite from sparks or static discharge.
6. Housekeeping is critical because it:
A. Improves decoration
B. Prevents accumulation of hazardous dust layers
C. Reduces electricity bills
D. Replaces engineering controls
Answer: B
Rationale: Proper cleaning reduces dust buildup that could
become airborne and ignite.
7. Which device is used to control explosion pressure?
A. Explosion vent
B. Water hose reel
C. Smoke detector
D. Thermostat
, Answer: A
Rationale: Explosion vents relieve pressure to minimize structural
damage during a deflagration.
8. What is a primary ignition source in dust environments?
A. Paperwork
B. Static electricity
C. Office lighting schedules
D. Nonconductive flooring alone
Answer: B
Rationale: Static discharge is a common ignition source if
grounding and bonding are inadequate.
9. Dust collectors should be located:
A. Inside confined offices
B. Outdoors or in protected areas when feasible
C. Next to break rooms
D. Under staircases
Answer: B
Rationale: External placement reduces the risk to personnel and
structures if an explosion occurs.
10. Which control reduces oxygen concentration?
A. Inerting
