Industrial fire and explosion hazards MCQs With Answer

Industrial fire and explosion hazards MCQs With Answer

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Introduction: This quiz set on Industrial Fire and Explosion Hazards is tailored for M.Pharm students studying Hazards and Safety Management. It focuses on the causes, properties, prevention, detection, and control measures relevant to fire and explosion risks in pharmaceutical manufacturing—where solvents, dusts, and reactive chemicals coexist. These MCQs emphasize core concepts such as flash point, autoignition, explosive limits, dust explosions, BLEVE, ignition sources, inerting, detection technologies, and regulatory classification. Practicing these questions will strengthen your ability to assess hazards, recommend engineering and administrative controls, and prepare safe operating procedures for laboratory and production environments in the pharmaceutical industry.

Q1. Which component added to the classic fire triangle creates the fire tetrahedron?

  • Heat
  • Fuel
  • Oxygen
  • Chemical chain reaction

Correct Answer: Chemical chain reaction

Q2. What is the best practical definition of the flash point of a flammable liquid?

  • The temperature at which a liquid boils
  • The temperature at which a liquid forms vapour that can momentarily ignite with a flame
  • The temperature at which a liquid spontaneously ignites without an external ignition source
  • The temperature at which the liquid becomes non-flammable

Correct Answer: The temperature at which a liquid forms vapour that can momentarily ignite with a flame

Q3. The Lower Explosive Limit (LEL) of a vapour is defined as:

  • The highest concentration of vapour in air that will propagate flame
  • The lowest concentration of vapour in air below which propagation of flame will not occur
  • The concentration of vapour at which autoignition occurs
  • The concentration where vapour becomes visible

Correct Answer: The lowest concentration of vapour in air below which propagation of flame will not occur

Q4. Autoignition temperature refers to:

  • The temperature at which a material melts
  • The minimum temperature at which a substance will ignite without an external spark or flame
  • The temperature at which a substance emits its maximum vapour pressure
  • The temperature at which combustion stops

Correct Answer: The minimum temperature at which a substance will ignite without an external spark or flame

Q5. BLEVE in process safety terminology stands for:

  • Boiling Liquid Explosive Volatile Event
  • Boiling Liquid Expanding Vapour Explosion
  • Burning Liquid Elevated Vapor Emission
  • Bulk Liquid Evaporation and Volatilization Event

Correct Answer: Boiling Liquid Expanding Vapour Explosion

Q6. Which of the following is commonly a primary ignition source in pharmaceutical facilities?

  • Static electricity
  • Hot surfaces and friction
  • Open flames and welding
  • All of the above

Correct Answer: All of the above

Q7. Which condition is NOT necessary for a dust explosion to occur?

  • Combustible dust
  • Dispersion of dust particles in sufficient concentration
  • Confinement or enclosure
  • Presence of a catalyst

Correct Answer: Presence of a catalyst

Q8. Which temperature parameter is the most useful single indicator for assessing safe handling and storage of flammable liquids?

  • Boiling point
  • Flash point
  • Melting point
  • Pour point

Correct Answer: Flash point

Q9. If a vapour has a vapor density greater than 1 (air = 1), what is the practical safety implication?

  • Vapour is lighter than air and disperses rapidly upward
  • Vapour is heavier than air and may accumulate in low-lying areas
  • Vapour is non-flammable
  • Vapour will automatically ignite at ambient temperature

Correct Answer: Vapour is heavier than air and may accumulate in low-lying areas

Q10. The purpose of inerting a storage tank containing flammable solvent vapour is to:

  • Remove the fuel by purging with air
  • Reduce oxygen concentration below that required to support combustion
  • Raise temperature to above autoignition
  • Add a flame retardant chemical to the liquid

Correct Answer: Reduce oxygen concentration below that required to support combustion

Q11. Which firefighting medium is generally most suitable for a significant spilled hydrocarbon liquid fire (Class B) in a process area?

  • Water jet
  • CO2 fixed system
  • Foam (aqueous film‑forming foam, AFFF)
  • Wet sand

Correct Answer: Foam (aqueous film‑forming foam, AFFF)

Q12. A primary mechanical consequence of a tank BLEVE is:

  • Long-term toxic contamination of soil
  • Pressure blast and projectiles from vessel rupture
  • Slow, smouldering combustion only
  • Immediate neutralization of vapours

Correct Answer: Pressure blast and projectiles from vessel rupture

Q13. A hot work permit is typically required for which of the following activities in a pharmaceutical plant?

  • Routine visual inspection of electrical panels with power off
  • Welding, cutting, brazing or grinding that produces sparks
  • Normal cleaning using low-flammability detergents
  • Sitting in an office adjacent to the production area

Correct Answer: Welding, cutting, brazing or grinding that produces sparks

Q14. Which type of gas detector is commonly used for continuous monitoring of combustible hydrocarbons (catalytic gases) in general industry?

  • Catalytic bead (pellistor) sensor
  • Optical particle counter
  • Electrochemical cell for oxygen
  • Infrared thermometer

Correct Answer: Catalytic bead (pellistor) sensor

Q15. Which analytical approach is most often used to quantify potential frequencies and consequences of industrial fires and explosions for siting and risk management?

  • Qualitative checklist only
  • Quantitative Risk Assessment (QRA)
  • Random sampling
  • Inventory counting

Correct Answer: Quantitative Risk Assessment (QRA)

Q16. The primary purpose of explosion venting in a process enclosure is to:

  • Increase internal pressure to blow open the vessel
  • Relieve pressure rapidly to reduce structural damage and protect personnel
  • Contain the explosion and prevent any external release
  • Convert the explosion into a fire

Correct Answer: Relieve pressure rapidly to reduce structural damage and protect personnel

Q17. To prevent electrostatic discharge ignition during solvent transfer, the most effective administrative/engineering control is:

  • Heating the solvent to boiling
  • Grounding and bonding of containers and pipelines
  • Using plastic drums instead of metal
  • Adding surfactants to the solvent

Correct Answer: Grounding and bonding of containers and pipelines

Q18. According to NEC/IEC hazardous location classification, areas where combustible dust may be present in the air in sufficient quantities to produce an explosion are classified as:

  • Class I (gases/vapours)
  • Class II (combustible dusts)
  • Class III (fibers)
  • Division 4 (non-existent)

Correct Answer: Class II (combustible dusts)

Q19. Which of the following is NOT a recognized method of explosion protection for process equipment?

  • Inerting to below limiting oxygen concentration
  • Explosion suppression systems
  • Explosion isolation devices to stop flame propagation
  • Deliberate heat addition to promote faster combustion

Correct Answer: Deliberate heat addition to promote faster combustion

Q20. In an emergency response to a major fire or explosion at a pharmaceutical plant, the highest priority objective is to:

  • Protect the company’s equipment and product stock
  • Preserve process documentation
  • Save and protect human life
  • Prevent media exposure

Correct Answer: Save and protect human life

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