Material Handling in Agro Industries Questions and Answers

Answer: C

Correct answer: Redesigning to need only one elevator

The two elevators contribute 0.5 per cent each, a full two thirds of the 1.5 per cent total, so removing one is worth more than any adjustment to the other stages. The general principle follows: lift once as high as needed and distribute by gravity thereafter, rather than lifting, lowering and lifting again.

Answer: D

By twelve metres the liquid model predicts more than twice the true floor pressure, because it ignores the weight the walls are carrying. Designing on the liquid assumption would oversize the floor and undersize the walls.

Answer: A

Damage in pneumatic conveying comes chiefly from impact at bends, and impact energy rises with the square of velocity. Dense phase moves the material slowly as a plug and is far gentler, at the cost of higher pressure equipment.

Answer: B

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

Both are true and the reason gives the limitation. Grain on a plain belt begins to roll back at around twenty degrees, so a vertical lift of any height would need an impossible length of belt. A bucket elevator carries the material in enclosed buckets, so the inclination is irrelevant and the lift can be vertical.

Answer: C

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

Both are true and the reason gives the mechanism. A screw does not carry the material; it pushes it along a stationary trough, so every particle is dragged against steel for the whole length of the run. Both the friction power and the attrition therefore grow with length, which is why screws suit short transfers and belts suit long ones.

Answer: D

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

Both are true and the reason gives the mechanism, which is Janssen’s analysis. Grain transmits part of its vertical load sideways to the wall, where friction supports it, so an increasing share of the weight is carried by the walls as depth increases. The lateral pressure is therefore substantial, and the vertical pressure on the floor approaches a limit rather than growing without bound.

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. Mass flow moves all the material whenever any is withdrawn, so nothing sits in the bin indefinitely and the discharge is first-in first-out. Funnel flow leaves stagnant regions where material can cake, spoil or become infested, which is why mass flow is specified for anything with a shelf life.

Answer: B

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

Both are true and the reason gives the principle. An explosion needs fuel, oxygen, an ignition source, dispersion and confinement all at once, so removing any one prevents it. Dust extraction attacks the fuel directly, at the transfer points where dust is generated, which is why it comes first; relief panels are what remain if that defence fails.

Answer: C

Correct answer: A is false but R is true

The reason is true and it is exactly why the assertion is false. Dilute phase conveying works by keeping particles suspended at high velocity, and impact damage at bends grows with the square of that velocity, so it is one of the harshest methods rather than the gentlest. Dense phase, which moves material slowly in plugs, is the gentle pneumatic option.

Answer: D

Correct answer: A is false but R is true

The reason is true and it condemns the assertion. Since outlet size governs every arching criterion, the reliable cure is to enlarge the outlet beyond the critical dimension, after which no arch can support itself. A vibrator treats the symptom, and often makes matters worse by compacting the material further into the arch.