For the same draught produced the power of induced draught fan as compared to forced draught fan is

Shikha went to the market to purchase five fans. The cost of the first fan is 25% more than the second fan and price of third fan is 20% less than fourth fan and price of fifth fan is 16% more than price of fourth fan. Price of the fourth fan is 3/4th of the second fan’s price. If the average cost of the first three fans was Rs.35 more than of the last three fans. What is the cost of the second costliest fan?

A

166

B

165.66

C

166.66

D

165

E

None of these

Power required in case of forced draught as compared to induced draught (for the same draught produced) is

A

Same

B

Less

C

More

D

Either more or less; depends on the flue gas density

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

A

768

B

549

C

392

D

332

In a furnace employing forced draught as compared to induced draught,

A

Air is sucked in, so air leaks are more and hence the furnace efficiency is reduced

B

The fan operates hot and hence blades are liable to corrosion and erosion

C

Positive pressure exists in the furnace

D

None of these

In a furnace employing forced draught compared to induced draught __________

A

the fan operates hot and hence blades are liable to corrosion and erosion

B

positive pressure exists in the furnace

C

air is sucked in, so air leaks are more and hence furnace efficiency is reduced

D

none of the mentioned

The fan drift pressure readings and fan quantities are measured to be 500 Pa and 65 m³/s respectively at the time when NVP aids fan pressure. On reversal, the fan delivers a quantity of 50 m³/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 Ns²/m⁸ will be

A

0.9487

B

0.2750

C

0.4105

D

0.1635

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.
Mine Ventilation mcq question image

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

The capacity of induced draft fan compared to forced draft fan in a boiler is

A

Same

B

More

C

Less

D

Less or more depending on size of boiler

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

A

50

B

350

C

500

D

650

Why is induced draught considered better than the forced draught?

A

Because power requirement is high for forced draught

B

Maintenance of induced draught fan is costlier

C

Forced draught is less efficient

D

Forced draught produces less amount of speed of air

For the same draught produced the power of induced draught fan as compared to forced draught fan is

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