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A pitot tube is inserted in a ventilation duct with the nose facing the air flow. A vertical U-tube manometer filled with alcohol (specific gravity 0.8) has been used for pressure measurements such that 10.2 mm is read as the total pressure and 8.8 mm as the static pressure. Given the density of air to be 1.2 kg/m<sup>3</sup>, the air velocity at the nose of the pitot tube in m/s is
A
4.27
B
6.53
C
3.29
D
5.67
Correct Answer:
4.27
A mercury (specific gravity = 13.6) manometer connected across an orificemeter fitted in a pipe shows a manometer reading of 2 cms. If the manometer liquid is changed to carbon tetrachloride (specific gravity = 1.6), then for the same flow rate of water the new manometer reading will be __________ cms.
A
17
B
42
C
84
D
1.8
Air at a density of 1.2 kg/m
3
flows in a straight duct such that the velocity at the centre is 12.5 m/s. the method factor for the velocity profile is known to be 0.80. The air flow encounters a symmetric expansion such that the cross- sectional are of the duct becomes double. The static pressure value at the inlet and outlet of the expansion are 60 Pa and 90 Pa respectively. Neglecting friction the shock pressure loss on account of expansion in Pa is
A
15
B
22
C
38
D
46
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
A continuous process is set up for treatment of wastewater. Each day, 103 kg cellulose and 105 kg bacteria enter in the feed stream, while 102 kg cellulose and 1.5 x 102 kg bacteria leave in the effluent. The rate of cellulose digestion by the bacteria is 8 x 102 kg d-1. The rate of bacterial growth is 4x 102 kg d-l; the rate of cell death by lysis is 6 x 102 kg d-1. Write balances for cellulose and bacteria in the system.
A
1× 103 kg, 9 × 103 kg
B
1× 102 kg, 9.965 × 104 kg
C
1× 103 kg, 9.964 × 104 kg
D
1× 102 kg, 9 × 103 kg
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
Use the following passage for the questions based on it. There are 6 flats on a floor in two rows. Out of these, three are north facing and the other three are south facing flats. The flats are to be allotted amongst Arun, Biswajyot, Chitra, Derek, Evan, and Fatima. Biswajyot gets a north facing flat and is not next to Derek. Derek and Fatima get diagonally opposite flats. Chitra is next to Fatima, and gets a south facing flat.Evan gets a north facing flat. Which of the following combination gets south facing flats?
A
Arun, Chitra and Fatima
B
Chitra, Biswajyot and Derek
C
Evan, Arun and Fatima
D
Derek, Arun and Biswajyot
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 total pressure and the static pressure measured at a point in a ventilation duct are 20 mm and 10 mm of water gauge respectively. If density of air is 1.2 kg/m
3
, the velocity of the air in m/s is
A
14.08
B
12.78
C
8.53
D
6.24
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
A
Area ABF + Area CDEF
B
Area ABRS + Area CDEF
C
Area ABRS + Area QDCR
D
Area ABF + Area QDCR
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