Contractor Exam Questions And

CA D21 Machinery & Pumps Contractor Exam Questions And Correct Answers (Verified Answers) Plus Rationale2026 Q&A| Instant Download Pdf

• What is the primary purpose of a centrifugal pump?
• Increase pressure in a system
• Move fluids from one location to another
• Reduce fluid velocity
• Filter fluid

Rationale: Centrifugal pumps are designed to transport fluids by

converting rotational kinetic energy to hydrodynamic energy.

• Which type of pump is best suited for high-viscosity fluids?
• Centrifugal pump
• Positive displacement pump
• Axial flow pump
• Peristaltic pump

Rationale: Positive displacement pumps move a fixed volume per cycle,

making them ideal for high-viscosity fluids.

• What is the primary hazard when operating high-speed machinery?
• Noise
• Vibration 1 / 3

• Mechanical entanglement
• Dust

Rationale: High-speed rotating machinery poses a risk of entanglement

with clothing or body parts.

• Which component of a pump prevents backflow?
• Impeller
• Shaft seal
• Check valve
• Bearing

Rationale: Check valves allow fluid flow in one direction only, preventing

backflow.

• What is the main function of a mechanical seal in a pump?
• Increase efficiency
• Control flow
• Prevent leakage along the shaft
• Reduce vibration

Rationale: Mechanical seals prevent fluid from leaking out along the pump

shaft.

6. Cavitation in a pump occurs when:

• Fluid is too viscous
• Vapor bubbles form due to low pressure
• Pump speed is too low
• Fluid is too hot

Rationale: Cavitation occurs when local pressure drops below vapor

pressure, forming bubbles that collapse and damage the pump.

• Which type of pump is most efficient for large volumes at low head?
• Positive displacement pump
• Gear pump
• Centrifugal pump
• Diaphragm pump 2 / 3

Rationale: Centrifugal pumps are efficient for high-flow, low-pressure

applications.

• What is the standard unit for pump flow rate?
• Pascals
• Cubic meters per hour (m³/h)
• Watts
• Newton

Rationale: Pump flow rate is typically measured as the volume of fluid

moved per unit time.

• Which type of maintenance is performed based on a schedule rather

than observed wear?

• Corrective maintenance
• Predictive maintenance
• Preventive maintenance
• Reactive maintenance

Rationale: Preventive maintenance is performed regularly to prevent

failure, regardless of condition.

• What is the main purpose of a pump’s impeller?
• Support the shaft
• Transfer energy to the fluid
• Control leakage
• Filter debris

Rationale: The impeller imparts kinetic energy to the fluid, creating flow

and pressure.

• Which of the following is a common pump efficiency factor?
• Shaft diameter
• Volumetric efficiency
• Pump weight
• Material hardness

Rationale: Volumetric efficiency measures how effectively the pump moves

the intended volume of fluid.

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