1. ______ is defined as the ratio of void containing wetting fluid and voids of both fluid.
a) Residual saturation
b) Effective saturation
c) Special saturation
Answer: b [Reason:] For defining the two phase systems, it is effective saturation Se that is commonly used, S¬e is used defined as the ratio of void containing wetting fluid and voids of both fluid.
2. Calculate Se, if the wetting fluid void is 2.5 m3 and the void containing both fluids is 8.5 m3?
Answer: d [Reason:] As Se = 2.5/8.5 = 0.294.
3. In a super centrifuge, if the radius of the basket is reduced 50% then ____
a) RPM is halved
b) RPM is doubled
c) RPM is tripled
d) No change in RPM
Answer: b [Reason:] If the radius of the basket is decreased by 50% then the revolutions per minute are doubled, than the linear speed of basket.
4. What are the speeds of basket centrifuge?
a) 15,000 rpm
b) 10,000 rpm
c) 50,000 rpm
d) 1000 rpm
Answer: a [Reason:] Speeds up to 1000 Hz are used to give accelerations 50,000 times the gravitational acceleration, the basket rotates at 15,000 rpm.
5. The degree of separation depends upon the ___
a) Thickness of liquid layer
b) Thickness of solid layer
c) Thickness of cake layer
d) Thickness of strip layer
Answer: a [Reason:] For a given feed rate to the centrifuge, the degree of separation depends upon the thickness of liquid layer at the walls of the baskets.
6. Mixing involves ____
a) Solid Liquid
b) Solid gas
c) Gas Liquid
d) Solid Liquid gas
Answer: d [Reason:] Mixing involves the mixing of gases, liquid or solids in any possible combination of two or more constituents.
7. Mixing can be best accomplished by the ____
Answer: a [Reason:] Mixing is accomplished by the rotation action of the impeller in the continuous fluid, also it can be done by agitation but is not economical.
8. Impellors are divided into ______
a) Initial and Final
b) Tangential and Torsional
c) Centrifuge and Torque
d) Axial and Radial
Answer: d [Reason:] Impellors may be roughly be dived into two broad classes mainly axial and radial flow type of impellors, it depends upon angle they make.
9. Axial flow impellors have _____
a) > 900
b) < 900
c) > 1800
d) < 1800
Answer: b [Reason:] These include all the impellors in which the blade makes an angle of less than 900 with the plane of the rotation.
10. Radial impellors are ____
Answer: a [Reason:] These impellors have blades which are parallel to the axis of shaft, or have an angle equals to 180 degrees with the shaft.