BECC Test 5 – Centrifugal Pumps, Hydraulic
Systems & Fluid Mechanics (Complete Exam 200+
Questions with Answers and Detailed Rationales |
2025 Edition)
Prepare thoroughly for your Basic Engineering Concepts & Components (BECC) certification
with this comprehensive Test 5 exam set. Covering centrifugal pump operation, components,
hydraulics, valves, priming systems, pressure control, cavitation, efficiency, and
maintenance, this 2025 edition
1. A fixed volume of liquid is discharged by a centrifugal pump. (True/False)
Answer: False
Rationale: Centrifugal pumps are variable-displacement devices; flow rate depends on head
pressure and system resistance, not a fixed volume per revolution.
2. Which centrifugal pump component prevents reverse flow of liquid through the pump when
it stops running?
Answer: Check valve
Rationale: A check valve or non-return valve (NRV) allows fluid to flow in only one direction,
preventing backflow that could damage the pump.
3. What is used to move fluid from one location to another?
Answer: Pump
Rationale: Pumps convert mechanical energy into fluid energy, creating flow and pressure to
transport liquids.
4. The rotating element of a centrifugal pump that imparts velocity to the fluid is called the:
Answer: Impeller
Rationale: The impeller transfers kinetic energy to the liquid, converting it into velocity and
partial pressure energy.
5. The casing of a centrifugal pump serves to:
,Answer: Convert velocity energy into pressure energy
Rationale: The volute casing collects high-velocity fluid from the impeller and gradually reduces
velocity, increasing pressure.
6. The mechanical device that connects the impeller to the driving motor is called the:
Answer: Shaft
Rationale: The shaft transmits torque from the motor to the impeller for rotation.
7. The suction side of a pump should be as short and straight as possible to:
Answer: Reduce friction and prevent cavitation
Rationale: Short, direct suction lines minimize air pockets and pressure losses, reducing the risk
of vapor bubble formation.
8. Cavitation in a centrifugal pump is caused by:
Answer: Vaporization of liquid at low pressure areas within the pump
Rationale: Cavitation occurs when local pressure drops below the liquid’s vapor pressure,
forming bubbles that collapse and damage the impeller.
9. Which of the following is a positive displacement pump?
Answer: Gear pump
Rationale: Gear pumps deliver a fixed volume per cycle, independent of discharge pressure,
unlike centrifugal pumps.
10. What is the main purpose of a priming process in centrifugal pumps?
Answer: Remove air from the suction line and casing
Rationale: Priming ensures the pump casing is filled with liquid, preventing air-lock and
allowing proper suction pressure development.
11. The energy added to a liquid by a pump is known as:
Answer: Head
Rationale: Pump head is a measure of energy per unit weight of fluid (usually expressed in
meters of liquid column).
12. The part of a centrifugal pump that supports the rotating shaft is called the:
Answer: Bearing
,Rationale: Bearings support the shaft, reduce friction, and maintain alignment during
operation.
13. The performance of a centrifugal pump is graphically represented by:
Answer: Pump characteristic curve
Rationale: The pump curve shows relationships among head, flow rate, efficiency, and power,
assisting in system design and selection.
14. The efficiency of a pump is defined as the ratio of:
Answer: Output hydraulic power to input mechanical power
Rationale: Efficiency = (Water horsepower / Brake horsepower) × 100, indicating how
effectively input energy becomes fluid energy.
15. The point at which a pump operates most efficiently is called the:
Answer: Best Efficiency Point (BEP)
Rationale: BEP represents the combination of head and flow where energy losses are minimal,
and mechanical stress is lowest.
16. Which valve is installed at the pump discharge to control flow rate?
Answer: Throttle valve
Rationale: Throttle valves (such as gate or globe valves) regulate discharge flow and head
without reversing flow direction.
17. A pump that must be completely filled with liquid before starting is known as a:
Answer: Non-self-priming pump
Rationale: Non-self-priming pumps (like most centrifugal types) cannot evacuate air and must
be filled before operation.
18. Net Positive Suction Head (NPSH) is important to prevent:
Answer: Cavitation
Rationale: Adequate NPSH ensures suction pressure remains above vapor pressure, avoiding
bubble formation and pump damage.
19. What type of energy transformation occurs in a centrifugal pump?
Answer: Mechanical energy to hydraulic energy
Rationale: The rotating impeller converts mechanical input into fluid motion (kinetic and
pressure energy).
, 20. Which component in a centrifugal pump prevents leakage along the shaft?
Answer: Mechanical seal or gland packing
Rationale: These sealing devices prevent fluid leakage between the rotating shaft and
stationary casing.
21. The static head in a pumping system is the:
Answer: Vertical distance between the liquid source and discharge point
Rationale: Static head reflects the elevation difference that must be overcome regardless of
friction losses.
22. Increasing impeller speed in a centrifugal pump will generally:
Answer: Increase flow rate and head
Rationale: Flow rate varies directly with speed, and head varies approximately with the square
of speed (affinity laws).
23. When two pumps are connected in series, the total effect is to:
Answer: Increase discharge head
Rationale: In series operation, discharge from one pump feeds the next, adding their heads
together at constant flow.
24. When two pumps are connected in parallel, the total effect is to:
Answer: Increase flow rate
Rationale: In parallel, pumps share suction and discharge lines, combining their flow capacities
at the same head.
25. Which safety device automatically stops a pump if pressure exceeds safe limits?
Answer: Pressure relief valve
Rationale: Relief valves protect equipment by diverting excess fluid when pressure surpasses
design limits.
26. The total head developed by a centrifugal pump is the sum of which two components?
Answer: Static head and friction head
Rationale: Total head includes the energy required to overcome elevation difference and
frictional losses in piping.
27. The impeller eye refers to which part of the centrifugal pump?
Systems & Fluid Mechanics (Complete Exam 200+
Questions with Answers and Detailed Rationales |
2025 Edition)
Prepare thoroughly for your Basic Engineering Concepts & Components (BECC) certification
with this comprehensive Test 5 exam set. Covering centrifugal pump operation, components,
hydraulics, valves, priming systems, pressure control, cavitation, efficiency, and
maintenance, this 2025 edition
1. A fixed volume of liquid is discharged by a centrifugal pump. (True/False)
Answer: False
Rationale: Centrifugal pumps are variable-displacement devices; flow rate depends on head
pressure and system resistance, not a fixed volume per revolution.
2. Which centrifugal pump component prevents reverse flow of liquid through the pump when
it stops running?
Answer: Check valve
Rationale: A check valve or non-return valve (NRV) allows fluid to flow in only one direction,
preventing backflow that could damage the pump.
3. What is used to move fluid from one location to another?
Answer: Pump
Rationale: Pumps convert mechanical energy into fluid energy, creating flow and pressure to
transport liquids.
4. The rotating element of a centrifugal pump that imparts velocity to the fluid is called the:
Answer: Impeller
Rationale: The impeller transfers kinetic energy to the liquid, converting it into velocity and
partial pressure energy.
5. The casing of a centrifugal pump serves to:
,Answer: Convert velocity energy into pressure energy
Rationale: The volute casing collects high-velocity fluid from the impeller and gradually reduces
velocity, increasing pressure.
6. The mechanical device that connects the impeller to the driving motor is called the:
Answer: Shaft
Rationale: The shaft transmits torque from the motor to the impeller for rotation.
7. The suction side of a pump should be as short and straight as possible to:
Answer: Reduce friction and prevent cavitation
Rationale: Short, direct suction lines minimize air pockets and pressure losses, reducing the risk
of vapor bubble formation.
8. Cavitation in a centrifugal pump is caused by:
Answer: Vaporization of liquid at low pressure areas within the pump
Rationale: Cavitation occurs when local pressure drops below the liquid’s vapor pressure,
forming bubbles that collapse and damage the impeller.
9. Which of the following is a positive displacement pump?
Answer: Gear pump
Rationale: Gear pumps deliver a fixed volume per cycle, independent of discharge pressure,
unlike centrifugal pumps.
10. What is the main purpose of a priming process in centrifugal pumps?
Answer: Remove air from the suction line and casing
Rationale: Priming ensures the pump casing is filled with liquid, preventing air-lock and
allowing proper suction pressure development.
11. The energy added to a liquid by a pump is known as:
Answer: Head
Rationale: Pump head is a measure of energy per unit weight of fluid (usually expressed in
meters of liquid column).
12. The part of a centrifugal pump that supports the rotating shaft is called the:
Answer: Bearing
,Rationale: Bearings support the shaft, reduce friction, and maintain alignment during
operation.
13. The performance of a centrifugal pump is graphically represented by:
Answer: Pump characteristic curve
Rationale: The pump curve shows relationships among head, flow rate, efficiency, and power,
assisting in system design and selection.
14. The efficiency of a pump is defined as the ratio of:
Answer: Output hydraulic power to input mechanical power
Rationale: Efficiency = (Water horsepower / Brake horsepower) × 100, indicating how
effectively input energy becomes fluid energy.
15. The point at which a pump operates most efficiently is called the:
Answer: Best Efficiency Point (BEP)
Rationale: BEP represents the combination of head and flow where energy losses are minimal,
and mechanical stress is lowest.
16. Which valve is installed at the pump discharge to control flow rate?
Answer: Throttle valve
Rationale: Throttle valves (such as gate or globe valves) regulate discharge flow and head
without reversing flow direction.
17. A pump that must be completely filled with liquid before starting is known as a:
Answer: Non-self-priming pump
Rationale: Non-self-priming pumps (like most centrifugal types) cannot evacuate air and must
be filled before operation.
18. Net Positive Suction Head (NPSH) is important to prevent:
Answer: Cavitation
Rationale: Adequate NPSH ensures suction pressure remains above vapor pressure, avoiding
bubble formation and pump damage.
19. What type of energy transformation occurs in a centrifugal pump?
Answer: Mechanical energy to hydraulic energy
Rationale: The rotating impeller converts mechanical input into fluid motion (kinetic and
pressure energy).
, 20. Which component in a centrifugal pump prevents leakage along the shaft?
Answer: Mechanical seal or gland packing
Rationale: These sealing devices prevent fluid leakage between the rotating shaft and
stationary casing.
21. The static head in a pumping system is the:
Answer: Vertical distance between the liquid source and discharge point
Rationale: Static head reflects the elevation difference that must be overcome regardless of
friction losses.
22. Increasing impeller speed in a centrifugal pump will generally:
Answer: Increase flow rate and head
Rationale: Flow rate varies directly with speed, and head varies approximately with the square
of speed (affinity laws).
23. When two pumps are connected in series, the total effect is to:
Answer: Increase discharge head
Rationale: In series operation, discharge from one pump feeds the next, adding their heads
together at constant flow.
24. When two pumps are connected in parallel, the total effect is to:
Answer: Increase flow rate
Rationale: In parallel, pumps share suction and discharge lines, combining their flow capacities
at the same head.
25. Which safety device automatically stops a pump if pressure exceeds safe limits?
Answer: Pressure relief valve
Rationale: Relief valves protect equipment by diverting excess fluid when pressure surpasses
design limits.
26. The total head developed by a centrifugal pump is the sum of which two components?
Answer: Static head and friction head
Rationale: Total head includes the energy required to overcome elevation difference and
frictional losses in piping.
27. The impeller eye refers to which part of the centrifugal pump?
