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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<br><img src="/images/question-image/mining-engineering/mine-ventilation/1682422639-M2-3-83-105.PNG" title="Mine Ventilation mcq question image" alt="Mine Ventilation mcq question image">
A
Area ABF + Area CDEF
B
Area ABRS + Area CDEF
C
Area ABRS + Area QDCR
D
Area ABF + Area QDCR
Correct Answer:
Area ABF + Area CDEF
A mine ventilation system consists of two splits A and B with resistances of 0.8 Ns
2
m
-8
and 3.2 Ns
2
m
-8
, respectively as shown in figure. Trunk airways have resistance of 0.2 Ns
2
m
-8
. The main mine fan is generating pressure of 500 Pa.
The flows in the two splits are equalized by placing a booster fan in split B. Assume that the fan pressure does not change after installation of the booster fan. The size of the booster fan in Pa is
A
749.05
B
850.08
C
950.02
D
1000.5
A mine ventilation system consists of two splits A and B with resistances of 0.8 Ns
2
m
-8
and 3.2 Ns
2
m
-8
, respectively as shown in figure. Trunk airways have resistance of 0.2 Ns
2
m
-8
. The main mine fan is generating pressure of 500 Pa.
The air quantities in m
3
/s circulated in the splits A and B respectively are
A
20 and 30
B
30 and 20
C
20 and 10
D
40 and 10
The main fan operating point of a ventilation system is shown in the figure below. If an NPV of 200 Pa assists the ventilation system, the resultant pressure (Pa) and quantity (m
3
) generated by the
A
500, 681
B
600, 63
C
640, 55
D
400, 63
E
640, 66
Two splits A and B are ventilated from an intake airway. Resistances of the splits are 0.5 Ns
2
m
-8
and 0.8 Ns
2
m
-8
respectively. A regulator is placed in split B to maintain a flow of 15 m
3
/s and 10 m
3
/s in splits A and B respectively as shown in the figure. The size of the regulator in m
2
is
A
2.1
B
1.3
C
1.2
D
1.13
While measuring average air velocity of air flowing through a circular duct using precise traversing with equal area method, the radii r
1
, r
2
and r
3
, in mm, as shown in the figure of the three circles should be
A
83, 167 and 240
B
36, 107 and 261
C
102, 177 and 228
D
108, 157 and 216
The resistances of each branches KL, LM, MN, NK is R and that of LN is 1.414 R. the equivalent resistance between K and M is
A
R
B
0.5 R
C
0.75 R
D
2 R
A pumping station in a mine has 4 pumps, P
1
, P
2
, P
3
and P
4
which are connected functionally in parallel configuration as shown in the figure. The individual reliability of the pumps P
1
, P
2
, P
3
and P
4
are 0.80, 0.90, 0.85 and 0.95 respectively. For an effective dewatering operation in the mine denoting system success, at least three pumps should be in operation. The reliability of the system is
A
0.19
B
0.93
C
0.99
D
0.58
A fan running at a speed of 280 rpm circulates 105 m
3
/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
A
768
B
549
C
392
D
332
The fan drift pressure readings and fan quantities are measured to be 500 Pa and 65 m
3
/s respectively at the time when NVP aids fan pressure. On reversal, the fan delivers a quantity of 50 m
3
/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 Ns
2
/m
8
will be
A
0.9487
B
0.2750
C
0.4105
D
0.1635
Pressure characteristic of a mine fan is given by. P = -0.06Q
2
+ 400. where P is the pressure in Pa and Q is the quantity in m
3
/s. The resistance of the mine is 0.19 Ns
2
/m
8
. An identical fan is installed in the mine to operate in series with the existing fan. The new mine quantity in m
3
/s is
A
75.6
B
56.7
C
50.8
D
30.2
