Home/Volume-2/Explosions in Mines Volume-2 Explosions in Mines Admin03/08/20240 26 Less than a minute Report a question What's wrong with this question? You cannot submit an empty report. Please add some details. 0% Explosions in Mines Explosions in Mines 1 / 33 1. The maximum explosive violence is produced when the explosive mixture contains firedamp? 5% 9% 15% 45% 2 / 33 2. The atmosphere becomes non-explosive irrespective of any % of firedamp if the minimum % of blackdamp is...? 35% 25% 20% 50% 3 / 33 3. Stone dust used for dusting should not contain.....free silica ? More than 30 % 5 to 30 % More than 5 % Less than 5 % 4 / 33 4. The water barrier must be sited at least .....m away from the stone dust barrier? 100 200 300 400 5 / 33 5. The time interval that elapses between application of a source of heat to firedamp air mixture and the actual moment of ignition of gas air mixture is? Incubation period Lag on ignition Ignition time Graham's ratio 6 / 33 6. The maximum air velocity preventing escape of moisture from the coal dust at working faces is? 8 m/s 6 m/s 4 m/s 2 m/s 7 / 33 7. In heavy stone dust barriers the amount of stone dust is loaded is? 60 kg/m 40 kg/m 30 kg/m 20 kg/m 8 / 33 8. Ignition temperature of methane is? 250 - 350 deg c 350 - 650 deg c 650 - 750 deg c 750 - 1000 deg c 9 / 33 9. In triggered barrier ...... is used ? Nitrogen Ammonia NaCl Brine 10 / 33 10. If the CH4 and air mixture is at 1000 deg C then the delay for ignition is? 20 sec 10 sec 5 sec 1 sec 11 / 33 11. The quantity of moisture that would ensure non propagation of flame by coal dust at least.....of the total mixture? 1/3 1/10 1/30 1/50 12 / 33 12. In longwall method the light type of stone dust barriers should be placed within the range of ...... m from the nearest point of the face? 50 - 120 150 - 200 200 - 350 350 - 400 13 / 33 13. For coal dust explosion the quantity of coal is.....g/cu.m ? 10 20 30 40 14 / 33 14. The lowest temperature at which a fine dry coal dust cloud can be ignited is ? 250 - 350 deg C 350 - 450 deg C 450 - 650 deg C 700 - 800 deg C 15 / 33 15. The maximum air velocity preventing escape of moisture from the coal dust at conveyor roads is? 8 m/s 6 m/s 4 m/s 2 m/s 16 / 33 16. The size of the coal dust particles dangerous to cause greater inflammability is ? 1/5 - 1/10 mm 1/10 - 1/15 mm 1/2 - 1/5 mm 1/1.5 - 1/2 mm 17 / 33 17. The water barriers must contain at least ...of water per sq.m of roadway cross section? 50 Liters 100 Liters 150 Liters 200 Liters 18 / 33 18. Lower limit of inflammability of coal dust is? 1 gm/cc 10 gm/cc 5 gm/cc 2000 gm/cu.m 19 / 33 19. Explosive limit of the CH4 is? 4.3 % to 45 % 4.3 % to 75 % 5 % to 15 % 4.3 % to 12 % 20 / 33 20. The atmosphere is non-explosive if the O2 percentage is? below 12 % 12 % to 20 % 20 % to 40 % 40 % to 50 % 21 / 33 21. The distance between water barriers must not exceed ....m in gate roads and .....m in main roads? 100 ; 200 200 ; 400 300 ; 500 500 ; 600 22 / 33 22. In light stone dust barriers the amount of stone dust is loaded is? 60 kg/m 40 kg/m 30 kg/m 20 kg/m 23 / 33 23. The coal is not likely to propagate flame for coal dust explosion if the coal containing of V.M ? Less than 13 % Less than 25 % More than 25 % More than 40 % 24 / 33 24. In longwall method the heavy type of stone dust barriers should be placed within the range of ...... m from the nearest point of the face? 50 - 120 150 - 200 200 - 350 350 - 400 25 / 33 25. The % of incombustible dust in the coal dust sample in a mine should be ....... for the stone to be effective in preventing propagation of flame? 10 - 20 % 20 - 40 % 40 - 50 % 50 - 60 % 26 / 33 26. In bord and pillar method of mining the stone dust barriers are placed .....m from the face? 50 - 100 100 - 150 150 - 400 400 - 500 27 / 33 27. For every 1 % firedamp the additional stone dust is required for efficient stone dusting is? 5 - 10 % 10 - 14 % 15 - 20 % 20 - 30 % 28 / 33 28. The amount of heat is required to burn the methane is ? 15 kcal/mole 19.5 kcal/mole 22.1 kcal/mole 25 kcal/mole 29 / 33 29. The stone dust barrier will fail if it located within minimum..... m from the face? 30 - 40 40 - 60 60 - 80 80 - 100 30 / 33 30. The higher limit of inflammability of coal dust is? 1 gm/cc 10 gm/cc 5 gm/cc 2000 gm/cu.m 31 / 33 31. The amount of stone dust which must be added to the coal dust to make it non explosive is ? Index of explosibility Index of inflammability Index idnitabolity Index of wettablity 32 / 33 32. The delay eliminates completely if the H2 % in methane is? 10 20 30 40 33 / 33 33. If the gas air mixture is compressed then the mixtures containing CH4 .....is inflammable? 1% 2 % to 75 % 75 % to 90 % above 90% Your score is The average score is 52% LinkedIn Facebook Twitter 0% Admin03/08/20240 26 Less than a minute
