Material Handling in Agro Industries 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 gives the cause. Because the load rides on the belt rather than being dragged over a stationary surface, the only friction to overcome is in the idlers and the belt itself. Power per tonne-metre is therefore very low and rises only gently with length, which is what makes belts the economical choice over long distances.

Answer: B

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: capacity comes from the load cross-section and the speed, and power grows with length. Statement 3 is far out - grain begins to roll back on a plain belt at about twenty degrees, and 45 degrees would need cleats or an entirely different machine.

Answer: C

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: mass flow leaves nothing stagnant, and enlarging the outlet is the reliable cure for bridging. Statement 3 misassigns ratholing, which is a funnel flow phenomenon - a rathole requires stagnant material around the flowing channel, and mass flow has none by definition.

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 describe dilute phase correctly. Statement 3 is the reverse of the truth: pneumatic conveying is much the most power-hungry method per tonne, because the air must be accelerated and moved as well as the material. Its advantages are flexible routing, complete enclosure and the ease of picking up from several points.

Answer: A

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: all five elements of the explosion pentagon must coincide, and relief panels limit the consequences rather than preventing the event. Statement 3 has the moisture effect backwards - damp material generates less airborne dust and is harder to ignite, so high moisture reduces the risk.

Answer: B

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

Four conveyors for four duties. A belt carries material over long horizontal runs at very low power per tonne. A bucket elevator lifts vertically at high capacity. A screw makes short enclosed transfers in a compact space, where its power and attrition penalties are small. And a pneumatic line offers flexible routing, ending at a cyclone that separates the material from the air.

Answer: C

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

Two flow patterns and two flow problems. Bridging is a self-supporting arch across the outlet; ratholing is a stable channel emptying through material that stays put. Mass flow moves everything whenever anything is withdrawn; funnel flow moves only a central core, which is the condition in which ratholes form.

Answer: D

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

Each property governs a different decision. Bulk density converts a volumetric flow into tonnes per hour, so it sets capacity. Angle of repose sets the surcharge profile on the belt and the slope a chute must have. Fragility decides whether a gentle or a harsh conveyor may be used. And abrasiveness sets the wear allowance on bends and troughs.

Answer: A

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

Four hazards with four distinct measures. Dust extraction at the transfer points attacks the explosion at its source by removing the fuel. Relief panels limit the structural damage if one occurs anyway. Fully enclosed conveyors keep the product clean. And fewer transfers with lower drop heights is the answer to breakage, which is a design decision rather than a fitting.

Answer: B

Correct answer: Pneumatic conveyor

A pneumatic conveyor moves material in a stream of air, with no mechanical member in contact with the product along the line - the energy comes from the blower and the transport medium is the air itself. The other three all use a moving mechanical element: buckets on a belt or chain, a rotating screw, and flights dragged through a trough.