Cleaning and Grading Equipment Questions and Answers

Answer: A

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason is the justification. Fruit varies in shape and density, so two of the same diameter can differ appreciably in mass, and a diameter sizer will place them in the same class. Where the fruit is sold by weight or packed to a count per tray, weighing each one gives a far more consistent pack, which repays the extra cost of the machine.

Answer: B

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: effectiveness combines the recovery of undersize in the fines and of oversize in the coarse stream, and capacity trades against it. Statement 3 is the reverse of the truth - a deeper bed buries the undersize so that it never reaches the deck, which is exactly why effectiveness falls as feed rate rises.

Answer: C

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: the indented cylinder works on length and the gravity table on density. Statement 3 misassigns the spiral separator, which exploits shape and rolling behaviour - round seeds roll and are thrown outwards, flat ones slide. Terminal velocity is what an aspirator uses.

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 describe the machine correctly: it combines screens with an aspiration stream, and that stream must be set between the terminal velocities of the chaff and the grain. Statement 3 is beyond it - a stone of the same size and terminal velocity as the grain passes both the screens and the air, which is why a separate destoner is needed.

Answer: A

Correct answer: 1 and 2 only

Statements 1 and 2 give the two aperture shapes correctly: a round hole passes a particle only if its width will go through, and a slot passes it only if its thickness will. Statement 3 is wrong - no aperture can sort on length, since a long particle passes end-on as readily as a short one, which is why length separation needs an indented cylinder or a disc separator.

Answer: B

Correct answer: A-2, B-1, C-4, D-3

Four machines and four different physical properties. The indented cylinder works on length, lifting short particles out in its pockets. The aspirator works on terminal velocity. The gravity table works on density, stratifying a fluidised bed. And the spiral separator works on shape and rolling behaviour, throwing round seeds outward while flat ones slide.

Answer: C

Correct answer: A-2, B-1, C-4, D-3

Four machines removing four different things. A destoner takes out stones and other dense foreign matter. A magnet takes out ferrous tramp metal, which would otherwise damage rolls or start a spark. A scalping screen removes oversize trash from the grain stream. And a cyclone recovers dust and chaff from the aspiration air rather than from the grain.

Answer: D

Correct answer: A-2, B-1, C-4, D-3

Four terms that recur in screening. Blinding is the plugging of apertures. Effectiveness is the combined recovery of both output streams, and so measures how well the separation was made. Specific capacity is throughput per unit of screen area, which is how a deck is sized. And scalping is the removal of oversize trash at the head of the line.

Answer: A

Correct answer: A-2, B-1, C-4, D-3

Each device measures a different dimension of the particle. A round perforation passes it if its width will go through; a slot if its thickness will. An indent seats it if it is short enough, so indents sort on length. And an inclined belt sorts on rolling behaviour, round particles rolling down while flat and irregular ones are carried up.

Answer: B

Correct answer: Specific gravity table

A gravity table separates on density, not size: two particles of identical dimensions but different densities go to opposite ends of the deck. The other three are all size separations - a diverging belt on fruit diameter, a sizing screen on width or thickness, and an indented cylinder on length, which is a size dimension even though a screen cannot measure it.