Engineering Questions with Answers - Multiple Choice Questions

Mechanical Operations MCQ’s – Screening Equipments

1 - Question

 What does the below equation represent?

a) Theoretical diameter
b) Theoretical speed
c) Minimum force
d) Minimum feed

View Answer

Answer: a
Explanation: The theoretical minimum diameter particle to be separated in a cyclone is given by the relation as mentioned above, where W is the width of cone and N is no. of turns.




2 - Question

For a good design, entrance velocities should be between ____
a) 500 to 1500 ft. /min
b) 1000 to 4000 ft. /min
c) 10 to 200 ft. /min
d) 500 to 800 ft. /min

View Answer

Answer: b
Explanation: Entrance velocities ranges from 1000 to 4000 ft. /min, 3000 ft. /min is good average although velocities up to 6000 ft. /min are used in special cases.




3 - Question

The larger the diameter, the _____ is pressure drop.
a) Large
b) Less
c) Same as
d) Constant

View Answer

Answer: b
Explanation: Small diameter has higher collection efficiency for the same entrance condition and pressure drop.




4 - Question

The efficiency for cyclone increases as
a) Pressure drop decreases
b) Pressure drop increases
c) Pressure drop is constant
d) No relation

View Answer

Answer: b
Explanation: The efficiency increases as the pressure drop increases that is a smaller separator might have higher efficiency due to higher gas velocity.




5 - Question

 What is the pressure drop range of a cyclone?
a) 0.5 to 8.0 inches
b) 1.0 to 5.0 inches
c) 5.0 to 6.0 inches
d) 5.0 to 8.0 inches

View Answer

Answer: a
Explanation: The pressure drop in a cyclone usually is between 0.5 to 8.0 inches of water, it can be large but rarely exceeds 10 inches of water.




6 - Question

What does the following represents?
hui = 0.003ρ Vc2

a) Inlet area
b) Inlet Velocity
c) Inlet head
d) Inlet pressure drop

View Answer

Answer: c
Explanation: Inlet velocity head on inlet area is given by the above relation, where p is the density of water and V is the velocity.




7 - Question

What does the below equation represent?

a) Pressure drop
b) Friction loss
c) Head loss
d) Depth loss

View Answer

Answer: a
Explanation: This equation represents the pressure drop, where De ¬and Dc is the cyclone gas exit and cyclone diameter in feet’s, K is a constant at 3.2.




8 - Question

 Calculate inlet head, if density of fluid is 12.3 kg/m3 and critical velocity is 58 m/s?
a) 123.13
b) 2.145
c) 15.22
d) 58

View Answer

Answer: a
Explanation: As we know that inlet head is 0.003*12.3*582 = 123.13 m.




9 - Question

Calculate pressure drop for a cyclone with De to Dc ratio of 3/4?
a) 2.333
b) 1.8
c) 9.6
d) 2.4

View Answer

Answer: b
Explanation: As we know that dP = K (De/ Dc)2 = 3.2 (3/4)2 = 1.8.




10 - Question

The overflow ratio is defined as ___
a) D/E
b) F/E
c) E/F
d) D/F

View Answer

Answer: d
Explanation: The overflow ratio is defined as the ratio of mass flow rate F and the mass flow rate of overflow i.e. D, so D/F.

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