Mechanical Operations problems
- 1. Pick out the wrong statement pertaining to the turbine agitator.
Options- A. Recommended peripheral speed for the turbine agitator is 200-250 metres/minute.
- B. Pitched blade turbine agitator gives only radial flow with complete absence of the axial flow.
- C. Generally, the diameter of the agitator is kept between l/3rd to l/6th of the tank diameter while the blade length is l/4th of agitator diameter (with central disc, it is l/8th of the agitator diameter).
- D. Turbine agitator should be located at a height not less than one agitator diameter length from the bottom. If the depth of liquid in the tank is more than twice the agitator diameter, two agitators should be used. Discuss
Correct Answer: Pitched blade turbine agitator gives only radial flow with complete absence of the axial flow.
- 2. Rittinger number which designates the new surface prduced per unit of mechanical energy absorbed by the material being crushed, depends on the
Options- A. state or manner of application of the crushing force.
- B. ultimate strength of the material.
- C. elastic constant of the material.
- D. all (a), (b) and (c). Discuss
Correct Answer: all (a), (b) and (c).
- 3. Half the angle of nip, (?), for a roll crusher is given by (where, dr, dp and df are diameters of crushing rolls, feed particles and rolls gap respectively).
Options- A.
- B.
- C.
- D.
Discuss
Correct Answer:
- 4. Which one is a filter aid?
Options- A. Convas fabric
- B. Diatomaceous earth
- C. Calcined lime
- D. None of these Discuss
Correct Answer: Diatomaceous earth
- 5. __________ conveyors are also called scrapers.
Options- A. Apron
- B. Screw
- C. Helical flight
- D. both (b) & (c) Discuss
Correct Answer: both (b) & (c)
- 6. Screen capacity is expressed in terms of
Options- A. tons/hr
- B. tons/ft2
- C. both (a) & (b)
- D. tons/hr-ft2 Discuss
Correct Answer: tons/hr-ft2
- 7. In a size reduction crushing operation, the feed size is 10 to 50 mm, while the product size is 2 to 10 mm. This is a case of __________ crushing.
Options- A. primary
- B. secondary
- C. fine
- D. ultrafine Discuss
Correct Answer: fine
- 8. With increase in the capacity of screens, the screen effectiveness
Options- A. remains unchanged
- B. increases
- C. decreases
- D. decreases exponentially Discuss
Correct Answer: decreases
- 9. To remove dirt from the flowing fluid, we use a
Options- A. coagulant
- B. gravity settler
- C. strains
- D. clarifier Discuss
Correct Answer: strains
- 10. Which of the following comes in the category of primary crusher for hard and tough stone?
Options- A. Jaw crusher
- B. Cone crusher
- C. Gyratory crusher
- D. None of these Discuss
Correct Answer: Jaw crusher
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