Aux 1 Unit 4 Q5

Correct Answer: C) Mechanical to kinetic and then to pressure energy

Explanation: In a centrifugal pump, mechanical energy from the motor is first converted into kinetic energy by the rotating impeller. As the fluid passes through the pump casing or diffuser, this kinetic energy is further converted into pressure energy.

Correct Answer: B) The pump must be pre-filled with liquid (primed)

Explanation: Before a centrifugal pump can start operating effectively, it must be primed by filling the pump casing with liquid. This ensures that the pump can generate the necessary suction to move the liquid through the system.

Correct Answer: B) The impeller

Explanation: The impeller is the key component of a centrifugal pump that rotates to impart kinetic energy to the fluid, converting mechanical energy into fluid velocity and pressure.

Correct Answer: B) They cannot create enough suction to draw in air and water from an unprimed state

Explanation: Centrifugal pumps are not self-priming because they cannot create enough suction to draw in air and water from an unprimed state. They require the pump casing to be filled with liquid before they can start operating effectively.

Correct Answer: B) To direct the fluid flow and convert kinetic energy into pressure

Explanation: The pump casing directs the fluid flow and helps convert the kinetic energy imparted by the impeller into pressure energy, which is necessary for the fluid to be transported through the system.

Correct Answer: B) To direct fluid from the impeller to the discharge while maintaining pressure

Explanation: The volute is a spiral-shaped casing that collects the fluid discharged from the impeller and directs it to the pump's discharge outlet, helping to maintain pressure as the fluid leaves the pump.

Correct Answer: B) It reduces the fluid’s velocity and further increases pressure

Explanation: The diffuser, which is sometimes used in centrifugal pumps, helps to slow down the fluid exiting the impeller, converting the remaining kinetic energy into additional pressure energy.

Correct Answer: B) The pump will overheat due to lack of fluid flow

Explanation: If a centrifugal pump is started without being primed, it will not be able to move fluid, leading to overheating due to friction within the pump. This can cause damage to the pump and reduce its lifespan.

Correct Answer: B) It controls the conversion of mechanical energy into fluid pressure

Explanation: The impeller's design is critical because it directly affects how efficiently the pump can convert mechanical energy from the motor into the pressure energy of the fluid, which determines the pump's overall performance.

Correct Answer: A) The fluid velocity decreases and pressure increases

Explanation: As the fluid moves from the eye of the impeller (the center) to the outer edges, its velocity decreases due to the expanding flow area, and its pressure increases due to the conversion of kinetic energy into pressure energy.