91. Which one of the following is used as a reviving apparatus in u/g coal mine?
92. When CO reacts with haemoglobin it changes in to . . . . . . . .
93. A mine ventilation system consists of two splits A and B with resistances of 0.8 Ns2m-8 and 3.2 Ns2m-8, respectively as shown in figure. Trunk airways have resistance of 0.2 Ns2m-8. The main mine fan is generating pressure of 500 Pa.
The air quantities in m3/s circulated in the splits A and B respectively are
The air quantities in m3/s circulated in the splits A and B respectively are
94. A sealed area known to have black damp has 18% O2, 2% CO2, and 78% N2. If fresh air has 21% O2, 0.03% CO2 and 78.97% N2, the percentage of black damp in the are is
95. Explosibility of H2 by volume is . . . . . . . .
96. Which one of the following composition of methane in air is most explosive in nature?
97. The wet kata for light manual workers is
98. Air samples collected from the intake and the return gates of a retreating longwall face show methane concentration values of 0.1% and 0.8% respectively. The production from the longwall face is 2000 tonne/day and the air quantity circulating the face is 15 m3/s. The rate of methane emission in m3 per tonne of coal produced is
99. In order to estimate the NVP in a mine, measurements are made at the main fan as shown below.
Fan speed (RPM)
Fan drift pressure (Pa)
Fan quantity (m3/s)
800
655
82.2
950
730
85.5
The NVP in Pa is
| Fan speed (RPM) | Fan drift pressure (Pa) | Fan quantity (m3/s) |
| 800 | 655 | 82.2 |
| 950 | 730 | 85.5 |
The NVP in Pa is
100. Match the following in the context of underground mine environment
Instrument
Measuring parameter
P. Haldane apparatus
I. Humidity
Q. Godbert-Greenwald apparatus
II. Air velocity
R. Hygrometer
III. Mine air composition
S. Anemometer
IV. Ignition point temperature
| Instrument | Measuring parameter |
| P. Haldane apparatus | I. Humidity |
| Q. Godbert-Greenwald apparatus | II. Air velocity |
| R. Hygrometer | III. Mine air composition |
| S. Anemometer | IV. Ignition point temperature |
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