# Separation Processes Questions and Answers – Centrifuge Devices for Solid Liquid Separations

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This set of Separation Processes Question Bank focuses on “Centrifuge Devices for Solid Liquid Separations”.

1. What are the two general types of centrifuge devices for solid-liquid separations?
a) Sedimentation centrifuges, filtering centrifuges
b) Sedimentation centrifuges, decantation centrifuges
c) Filtering centrifuges, sintering centrifuges
d) Sedimentation centrifuges, two way centrifuges

Explanation: The two general types of centrifuge devices for solid-liquid separations are Sedimentation centrifuges, filtering centrifuges.

2. What is the use of tubular-bowl centrifuge?
a) To separate soap from oil
b) To separate waste material
c) To separate cells and viruses from broth
d) To separate salts from mixtures

Explanation: The tubular-bowl centrifuge is used to separate cells and viruses from broth.

3. In which industry tubular-bowl centrifuge not used?
a) Food industry
b) Pharma industry
c) Biochemical industry
d) Metallurgical industry

Explanation: The tubular-bowl centrifuge is used to separate cells and viruses from broth and hence has no use in the metal industry.
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4. When is the basket-filtering centrifuge not used?
a) Solids are main product
b) Low cake moisture content
c) High solid recovery desired
d) High liquid recovery desired

Explanation: When high liquid recovery is desired, basket filtering centrifuge is not used.

5. Why are gravity separators not used in bioseparations?
a) Because density differences are very large
b) Because density differences are very small
c) Because gravity separators are too small
d) Because the cultures get damaged

Explanation: Gravity separators are not used in bioseparations because density differences are very small.

6. Calculate the sigma factor for the following operating conditions
Bowl length L=0.1m
Rotation rate n=2000/s
R0=0.02m, R1=0.01m
a) 50
b) 55
c) 111
d) 165

Explanation: Sigma factor= Lω2(R02-R12)/gln(R0/R1), hence sigma factor= 55m.

7. Calculate the sigma factor for the following operating conditions
Bowl length L=0.2m
Rotation rate n=2000/s
R0=0.02m, R1=0.01m
a) 50
b) 55
c) 111
d) 165

Explanation: Sigma factor= Lω2(R02-R12)/gln(R0/R1), hence sigma factor= 111m.

8. Calculate the sigma factor for the following operating conditions
Bowl length L=0.3m
Rotation rate n=2000/s
R0=0.02m, R1=0.01m
a) 50
b) 55
c) 111
d) 165

Explanation: Sigma factor= Lω2(R02-R12)/gln(R0/R1), hence sigma factor= 111m.

9. Calculate the sigma factor for the following operating conditions
Bowl length L=0.05m
Rotation rate n=2000/s
R0=0.02m, R1=0.01m
a) 27
b) 55
c) 111
d) 165

Explanation: Sigma factor= Lω2(R02-R12)/gln(R0/R1), hence sigma factor= 27m.

10. Calculate the sigma factor for the following operating conditions
Bowl length L=0.1m
Rotation rate n=4000/s
R0=0.02m, R1=0.01m
a) 323
b) 212
c) 234
d) 222

Explanation: Sigma factor= Lω2(R02-R12)/gln(R0/R1), hence sigma factor= 222m.

Sanfoundry Global Education & Learning Series – Separation Processes.

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