a. b. C. 4. a. b. c. Multiple choices: 20 Points (circle the letter of the right answer) 1. Required in estimating air quantities and in the evaluation of air quality such as lower air quality in the workplace will be generally found for mining methods that require the ventilation in large stopes and mining methods using backfill generally result in lower air leakage and recirculation problems. a. Mining methods d. Mine layout b. Production rate e. Environmental requirements Mining methods and production rate f. Mining methods and mine layout 2. A consideration in mine ventilation design where the inlet air temperatures should be incorporated in predicting seasonal ambient mine air temperature: Airway resistance d. Gas emissions Mine fines e. Thermodynamics c Airborne dust 3. An approach to view the cause of natural ventilation between two columns of equal height, the heavier intake air column sinking and the lighter air column rising, to determine the natural ventilation results: a. Thermodynamic approach d. Temperature difference b. Density difference e. Fifth principal performance factor Pressure difference A fan must be selected for a range of application and its performance be variable within limits as a working mine continually changes its: Size d. Friction factor Resistance e. a, b and Airflow requirements d. a, b, c and a 5. Speed change of centrifugal or axial fans cause a variation in power: Square e. Linear b. Direct f. Exponential Constant 8. None of the above d. Cubic 6. Most fans are designed to operate safely, satisfactorily, and economically over an operating range: Safely d. Efficiently b. Satisfactorily e. a, b and Economically f. a, b, c and d 7. Costs incurred regardless of whether an airway is used. Variable costs d. Operating costs b. Fixed costs e. Maintenance costs annual maintenance cost f. Supplies and materials costs 8. A result of changes in the direction of or area of an airway: Velocity head loss d. Shock loss b. Head loss e. Friction head loss c. Static head loss 9. Represent a loss to the system at the discharge: a. Velocity head loss d. Shock loss b. Head loss e. Friction head loss c. Static head loss 10. The friction losses in airflow through mine openings constitute of the sum of the head losses in typical mine ventilation system.: 60 to 8096 d. 65 to 8596 b. 50 to 70% e. 55 to 7596 c. 70 to 90% a. a. c. a. c. a. a