30 MCQ Questions and Answers on Mine Ventilation | Mining Engineering | Indian Minerology

30 MCQ Questions and Answers on Mine Ventilation

Prepare for mining engineering exams with these carefully selected multiple-choice questions (MCQs) focused on mine ventilation concepts, calculations, and safety standards.

1. What is the minimum percentage of oxygen required in mine air as per Indian mining laws?

a) 25% b) 21% c) 19% d) 17%

Answer: b) 21%

2. Which instrument is used to measure air velocity in mine ventilation?

a) P. Haldane apparatus b) Godbert-Greenwald apparatus c) Hygrometer d) Anemometer

Answer: d) Anemometer

3. In mine ventilation, the motive column is affected primarily by:

a) Air density differences b) Temperature differences between upcast and downcast shafts c) Wind velocity outside the mine d) Length of the airway

Answer: b) Temperature differences between upcast and downcast shafts

4. The formula for the quantity of air flow through two or more openings due to wind effect is:

a) Q = K × A × V b) Q = K / (A × V) c) Q = (A × V) / K d) Q = K + A + V

Answer: a) Q = K × A × V (where K is coefficient, A = area, V = wind velocity)

5. What happens to pressure consumption if the cross-sectional area of an airway is increased but air quantity remains the same?

a) Pressure consumption increases b) Pressure consumption decreases c) Pressure remains unchanged d) Pressure varies unpredictably

Answer: b) Pressure consumption decreases

6. What is the primary cause of timber decay in mines?

a) Methane (CH₄) b) Oxygen absorption by fungus c) Nitrogen depletion d) Carbon dioxide (CO₂)

Answer: b) Oxygen absorption by fungus

7. If a fan running at 500 rpm delivers 70 m³/s of air, what will be the air quantity if the speed reduces to 200 rpm?

a) 175 m³/s b) 55 m³/s c) 28 m³/s d) 11 m³/s

Answer: c) 28 m³/s

8. The principle on which mechanical ventilation is based is:

a) Natural air currents b) Forced air movement using fans c) Temperature gradients only d) Air leaks in mine shafts

Answer: b) Forced air movement using fans

9. What is the resistance unit commonly used in mine ventilation calculations?

a) Ns²/m⁸ b) Pascal (Pa) c) Newton (N) d) Cubic meter per second (m³/s)

Answer: a) Ns²/m⁸

10. Flame safety lamps are extinguished when oxygen content falls below:

a) 21% b) 19% c) 17.5% d) 15%

Answer: c) 17.5%

11. What is the typical range of air velocity for mine ventilation ducts?

a) 2 to 10 m/s b) 10 to 20 m/s c) 20 to 30 m/s d) 30 to 40 m/s

Answer: a) 2 to 10 m/s

12. Airflow rate in a mine is expressed in:

a) Cubic meters per minute b) Liters per second c) Cubic feet per minute d) All of the above

Answer: d) All of the above

13. What is the primary purpose of an upcast shaft in mine ventilation?

a) To draw fresh air into the mine b) To exhaust stale air out of the mine c) To transport miners d) To pump water

Answer: b) To exhaust stale air out of the mine

14. In calculating mine air resistance, which factor has the greatest impact?

a) Cross-sectional area of airway b) Length of the airway c) Surface roughness d) All of the above

Answer: d) All of the above

15. What describes the 'Natural Ventilation' in mines?

a) Ventilation by fans b) Ventilation due to temperature and pressure differences c) Ventilation forced by pumps d) Manual air circulation

Answer: b) Ventilation due to temperature and pressure differences

16. What gas is known as "Black Damp" in mines?

a) Methane (CH₄) b) Carbon Monoxide (CO) c) Carbon Dioxide (CO₂) and Nitrogen (N₂) d) Oxygen (O₂)

Answer: c) Carbon Dioxide (CO₂) and Nitrogen (N₂)

17. Which fan type is commonly used in mine ventilation?

a) Axial fan b) Centrifugal fan c) Mixed flow fan d) Propeller fan

Answer: b) Centrifugal fan

18. What is the function of a booster fan in mine ventilation?

a) To increase the air flow in one branch of the mine airway b) To reduce air temperature c) To remove toxic gases d) To regulate air pressure

Answer: a) To increase the air flow in one branch of the mine airway

19. The ventilation rate in a coal mine must be directly proportional to:

a) Mining height b) Number of miners c) Production rate d) Methane emission

Answer: d) Methane emission

20. What is "NVP" in mine ventilation?

a) Net ventilating pressure b) Nominal ventilation power c) Natural ventilation potential d) Net ventilation pressure

Answer: d) Net ventilation pressure

21. What does the term "regulator" mean in mine ventilation?

a) A device controlling air quantity b) A device measuring methane concentration c) A safety lamp type d) A pump for water

Answer: a) A device controlling air quantity

22. The velocity pressure in a ventilation duct is calculated using which parameters?

a) Air velocity and air density b) Air pressure and volume c) Air temperature and humidity d) Fan speed and duct area

Answer: a) Air velocity and air density

23. Which gas is explosive and often found in coal mines, requiring careful ventilation control?

a) Carbon dioxide b) Methane c) Carbon monoxide d) Nitrogen

Answer: b) Methane

24. What is the effect of increasing the diameter of a ventilation shaft in a mine?

a) Increase air velocity b) Decrease air flow c) Decrease air velocity and reduce resistance d) Increase resistance

Answer: c) Decrease air velocity and reduce resistance

25. The 'stack effect' in mine ventilation refers to:

a) Airflow created due to heat and density differences b) Airflow due to mechanical fans c) Air leaks through cracks d) Air circulation by workers

Answer: a) Airflow created due to heat and density differences

26. A regulator is placed in a mine airway to:

a) Increase air temperature b) Control or reduce air flow c) Measure air velocity d) Remove dust particles

Answer: b) Control or reduce air flow

27. What is the main characteristic of 'natural ventilation' in mines?

a) Powered fans b) Air circulation caused by natural forces like wind and temperature difference c) Mechanical blowers d) Use of compressed air

Answer: b) Air circulation caused by natural forces like wind and temperature difference

28. The effect of methane layering in a coal mine can be reduced by:

a) Increasing air velocity b) Methane drainage techniques c) Increasing miner numbers d) Reducing ventilation quantity

Answer: b) Methane drainage techniques

29. What principle is used by the Godbert-Greenwald apparatus?

a) Measuring temperature b) Measuring methane concentration c) Measuring air velocity d) Measuring humidity

Answer: b) Measuring methane concentration

30. The term “Motive Column” in mine ventilation refers to:

a) Difference in air pressure created by fans b) Height difference producing density-driven air pressure c) Length of the ventilation system d) Volume of mine air currents

Answer: b) Height difference producing density-driven air pressure