The percentage of inflammable gas in an u/g coal mine should not exceed
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Mining Engineering · all questionsMine Ventilation
Mine Ventilation
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A gas mixture contains CH4, C2H6 and H2 with respective concentration of 75%, 15% and 10% by volume. The lower explosibility limit of CH4, C2H6 and H2 are 5.0%, 3.3% and 4.2% respectively. The lower explosibility limit of the gas mixture, in percentage, is
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The voltage range of D6 methanometer . . . . . . . .
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Ascensionally ventilated coal mine inclines ideally should have a higher methane layering number when compared to descensionally ventilated inclines. The reason is
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An air sample produces 8% CH4 and 3% H2. If the lower flammability of CH4 is 5% and H2 is 4%, what is the lower flammability of the mixture?
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Which one of the following is used as an escape apparatus in u/g coal mine?
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The fan drift pressure readings and fan quantities are measured to be 500 Pa and 65 m3/s respectively at the time when NVP aids fan pressure. On reversal, the fan delivers a quantity of 50 m3/s while acting against NVP with fan drift pressure of 600 Pa. Assuming that the NVP remains constant in both cases the total resistance of the mine in Ns2/m8 will be
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Samples of air collected in the intake and return gate roads of an advancing long wall face show 0.25% and 0.75% CH4, respectively. The panel has a production of 400t in an 8 hour shift when an air quantity of 18 m3/s passes through it. Then the methane emission in m3/te of coal mined is
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The type of fire extinguisher that must NOT be used in case of fire in an electric substation located in an underground metal mine is
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The S.I. unit of barometric pressure is
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For the same roadway roughness, area, length and velocity condition the ratio of resistances of a square roadway to that of a rectangular roadway having width and height ratio. 2 : 1 is
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The mean velocity of air current through an airway of 9m2 cross-sectional area is found to be 1.5 m/s, If the mean methane content of air current is 0.6%, the layering index will be
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Air at dry bulb temperature of 27°C enters a 1200 m deep shaft. The specific heat of air-water vapour mixture is 1.03 KJ/kg °C. If the air goes through constant-moisture adiabatic auto compression, the air temperature at the bottom of the shaft in °C is
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The blade tip speed of a backward bladed centrifugal fan running at 300 rpm delivers 120 m3/s of air. If the tip speed of the blade is 47.12 m/s and width of the fan is 1.3 m then the radial velocity of air at the periphery of the impeller in m/s is
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An underground coal mine panel produces 520 tonnes per day deploying 220, 200 and 192 persons in three shifts. As per CMR 1957, the minimum quantity of air in m3/min to be delivered at the last ventilation connection of the panel is
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The formula for finding the velocity of air . . . . . . . .
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Match the following:
| Mine gas | Principal constituent |
| P. Stink damp | 1. CO |
| Q. White damp | 2. H2S |
| R. Black damp | 3. CH4 |
| S. Fire damp | 4. CO2 |
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The lower and upper limit of methane - air explosive mixture is
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The sp.gr of CO2
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In a mine between upcast shaft and downcast shaft, two airways are connected in parallel and their resistances are 100 and 120 Ns-2m-8 respectively. The resistance of upcast shaft, downcast shaft and the fan drifts are 10, 20, and 5 Ns-2m-8 respectively. The rate of airflow through the split airway having resistance of 100 Ns-2m-8 in m3/s is
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