The liquid employed in aneroid barometer.
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Mining Engineering · all questionsMine Ventilation
Mine Ventilation
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The mechanical mixture of gases existing in a mine given off after explosion called
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A Drager Gas Mask does not filter
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The resistances of two splits A and Bare 0.35 Ns2m-8 and 0.05 Ns2m-8 respectively. The combined resistance of the shafts and trunk airways is 0.4 Ns2m-8. A booster fan is planned to be installed in split A to increase the quantity flowing through it. Assuming that the surface fan continues to operate at a constant pressure of 1000 Pa, the critical pressure of the booster fan in Pa is
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A mine airway having cross-section of 2.2 m × 2.2 m and length 500 m contains a bend. Given that the airway friction factor is 0.01 Ns2m-4, shock loss factor for the bend is 0.07 and density of air is 1.2 kg/m3, the equivalent length of the airway in m is
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Methane detector works on the principle of diffusion combustion contraction is
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A mine fan delivers 50 m3/s of air at a fan drift of 10 mm of w.g. It is proposed to increase the quantity to 60 m3/s of air. the required w.g. shall be
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When two identical and parallel intake roadways are changed to three identical and parallel intake roadways of same size and length, the ratio of new equivalent resistance to old equivalent resistance will be
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The oxygen concentration in u/g working should not be less than
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Which can be found by blotting paper soaked in lead acetate changes its colour black.
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In a coal mine district, air flows at a rate of 30 m3/s at a pressure of 1200 Pa. The density of air is 1.2 kg/m3. The mine management decided to reduce the flow rate of air to 20 m3/s using a regulator without changing the ventilation pressure. The area of regulator expressed in m2 will be
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After blasting which gas come out.
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A Roadheader district produces 20 mg/m3 of airborne dust with the following size distribution:
The concentration of respirable fraction of dust in mg/m3 is
| Size up to | Cumulative wt% |
| 1 μm | 1 |
| 5 μm | 5 |
| 10 μm | 10 |
| 20μm | 20 |
| 50μm | 50 |
| >50μm | 100 |
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The wet bulb temperature of air at a particular place in a mine is 31°C, then the velocity of air in that place should be
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Intake air containing 0.2% methane enters a section of an underground mine where emission of methane is 0.05m3/s. Assuming that the threshold limit value of methane is 1.25%, the minimum quantity of fresh air required in m3/s is
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The figure shows PV (pressure-volume) diagram of a mine ventilated by both natural means and an exhaust fan. The total ventilation energy is represented by
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The black damp accumulates . . . . . . . . to the floor
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The inflammable gas should be below . . . . . . . . % in the general body of the retunr air way of any ventilating district and below . . . . . . . . % at any place in the mine.
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A centrifugal fan rotating at 500 rpm. delivers 70 m3/s of air. If the speed is reduced to 200 rpm. the quantity of air delivered in m3/s will be
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A fan running at a speed of 280 rpm circulates 105 m3/s of air in a mine. If the power input to the motor for driving the fan is recorded to be 75 kW, with the combined efficiency of fan and motor at 70%. If the fan pressure is to be increased by 200 Pa by changing the fan speed. the fan speed in rpm will become
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