Home/Volume-2/Underground Environment and Mine Ventilation Volume-2 Underground Environment and Mine Ventilation Admin03/08/20240 164 Less than a minute Report a question What's wrong with this question? You cannot submit an empty report. Please add some details. 0% Underground Environment and Mine Ventilation Underground Environment and Mine Ventilation 1 / 36 1. Upto what depth from the surface the temperature is constant? 20m 25m 10m 15m 2 / 36 2. The difference between the atmospheric pressure and the total pressure on the fan drift is called? Velocity pressure of surface fan Static pressure Total pressure of surface fan none 3 / 36 3. The minimum quantity of air per person in deg III mine is? 6 cu.m/min 8 cu.m/min 10 cu.m/min 12 cu.m/min 4 / 36 4. In the centrifugal fan reentry of the discharged air is prevented by? spiral casing blades evasee eye 5 / 36 5. The inclined water gauge can read upto? 2 mm 1.5 mm 1 mm 0.2 mm 6 / 36 6. The mostly used blade type in centrifugal fan is? backward radial forward none 7 / 36 7. Static pressure is measured by? Barometer Pitot tube Venturi meter U-tube 8 / 36 8. By varying the pitch of the blades the pressure generated by axial flow fan is? remains same decreases increases increases 8 times 9 / 36 9. The maximum permissible speed of the axial flow fan is? 8000 m/min 6000 m/min 5200 m/min 4200 m/min 10 / 36 10. For comfortable working conditions the reasonable velocity of air at the working face is? 0.5 to 2 m/s 3 to 4 m/s 5 m/s 6 m/s 11 / 36 11. The water gauge of an axial flow fan can be increased by? increasing speed of rotation changing the pitch of blades installing 2 or more stages enlarging the evasee of the fan 12 / 36 12. With an axial fan, the direction of travel of air current to the mine is changed by? changing direction flow of air into fan by means of doors changing the blades on the rotor changing the direction of rotation of the motor not possible with this type of fan 13 / 36 13. Velocity pressure is measured by? Barometer Inclined manometer U-tube Pitot tube 14 / 36 14. The presence of Nitrous fumes are detected by? The rotten eggs smell sweet smell metallic taste on tongue headache 15 / 36 15. The manometric efficiency of axial flow fan is? 10 to 20 % 70 to 85 % 20 to 30 % 40 to 50 % 16 / 36 16. The pitch of the blades of axial flow fans is? 1 to 5 deg 5 to 10 deg 10 to 15 deg 15 to 20 deg 17 / 36 17. With a centrifugal fan for a given quantity of air increase of efficiency and reduction in cost of power can be obtained with? well designed blades of the fan well designed spiral casing well designed evasee well designed eye of the impeller 18 / 36 18. The speed of the centrifugal fan is? 1 to 100 rpm 100 to 300 rpm 300 to 1000 rpm above 1000 rpm 19 / 36 19. Geothermic gradient in Indian coal seam is....? 1 deg c per 15 m 1 deg c per 38m 1 deg c per 50 m none 20 / 36 20. Ordinary U-tube manometers are not useful for measurement of gas velocities? below 12 m/s 13 to 20 m/s 20 to 30 m/s above 30 m/s 21 / 36 21. If the wet bulb temperature exceeds 30.5 deg c at any place air current should be faster than? 1 m/s 2 m/s 3 m/s 0.5 m/s 22 / 36 22. Cooling power is a combination of temperature of air; relative humidity and ...? Moisture content of air density of air velocity of air Pressure 23 / 36 23. The wet bulb temperature in development faces should not exceed? 30 deg c 33.5 deg c 35 deg c 38 deg c 24 / 36 24. The velocity of air flowing in a drift where the velocity pressure is 36 mm is? 36 m/s 24 m/s 42 m/s 48 m/s 25 / 36 25. The value of the kata factor is? 250 300 380 480 26 / 36 26. For light manual workers the wet kata is? 18 25 30 8 27 / 36 27. The noxious and inflammable gases of old workings of a coal mine expand when there is? sudden rise of temperature sudden heavy roof fall sudden rise in barometric pressure sudden drop in barometric pressure 28 / 36 28. Whirling hygrometer is rotated with a speed of? 100 rpm 200 rpm 300 rpm 400 rpm 29 / 36 29. The overall efficiency of axial flow fan is? 10 to 20 % 70 to 85 % 20 to 30 % 40 to 50 % 30 / 36 30. In the centrifugal fan smooth flow air and conversion of velocity energy into pressure energy takes place? In spiral casing In the blades At the tip of the blades In the evasee 31 / 36 31. The water gauge developed and quantity circulated with an axial flow fan depend on? Size of the fan Shape of the blades Design of the evasee Speed of the blade tips 32 / 36 32. The maximum water gauge developed in axial flow fan is? 10 cm 12.5 cm 13.5 cm 15 cm 33 / 36 33. Cooling power by conduction convection and radiation is given by using the? dry bulb temperature wet bulb temperature Average time of wet and dry bulbs wet and dry bulb time and velocity of air 34 / 36 34. The instrument that is used to measure the relative humidity is? pitot tube aneroid barometer hygrometer anemometer 35 / 36 35. Inclined water gauge is used for the measurement of water gauge for? smaller than 200 mm greater than 200 mm smaller than 50 mm greater than 50 mm 36 / 36 36. The unit for the kata factor is? millicalories/sq.cm/sec kcal/sec/sq.cm millicalories/sq.cm millicalories/sec/sq.cm Your score is The average score is 58% LinkedIn Facebook Twitter 0% Admin03/08/20240 164 Less than a minute
