31. The methane air mixture become explosive with the minimum percentage of oxygen.
32. 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%. the fan pressure in Pa is
33. Pressure characteristic of a mine fan is given by. P = -0.06Q2 + 400. where P is the pressure in Pa and Q is the quantity in m3/s. The resistance of the mine is 0.19 Ns2/m8. The mine quantity in m3/s is
34. Two splits A and B are ventilated from an intake airway. Resistances of the splits are 0.5 Ns2m-8 and 0.8 Ns2m-8 respectively. A regulator is placed in split B to maintain a flow of 15 m3/s and 10 m3/s in splits A and B respectively as shown in the figure. The size of the regulator in m2 is
35. Quantity of air to be circulated to u/g workings depends on
36. Determine the correctness or otherwise of the following Assertion [a] and the Reason [r].
Assertion: Both intake and return side stoppings must closed simultaneously in the event of sealing off a coal mine panel with explosion hazard following a fire.
Reason: By continuously ventilating the area till simultaneously closure of the stoppings, the possibility of an explosion hazard due to gas built is avoided.
Assertion: Both intake and return side stoppings must closed simultaneously in the event of sealing off a coal mine panel with explosion hazard following a fire.
Reason: By continuously ventilating the area till simultaneously closure of the stoppings, the possibility of an explosion hazard due to gas built is avoided.
37. Critical pressure of oxygen.
38. Moody diagram represents resistance coefficient in terms of
39. Given the following.
Rescue apparatus
Characteristic
P. Draeger BG-4
1. Open circuit chemical oxygen self-rescuer
Q. MSA IW-65
2. Filter type self-rescuer
R. Draeger Pulmotor
3. Self-contained breathing apparatus
S. Oxvoks
4. Resuscitation apparatus
The correct match is
| Rescue apparatus | Characteristic |
| P. Draeger BG-4 | 1. Open circuit chemical oxygen self-rescuer |
| Q. MSA IW-65 | 2. Filter type self-rescuer |
| R. Draeger Pulmotor | 3. Self-contained breathing apparatus |
| S. Oxvoks | 4. Resuscitation apparatus |
The correct match is
40. Which of the following instrument is used to measure the cooling power of the air?
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