21 Questions
What is the primary function of a centrifugal pump?
Convert mechanical energy into pressure energy
How does the flow occur in centrifugal pumps?
Radial outward direction
What type of flow principle does a centrifugal pump work on?
Forced vortex flow
What part of a centrifugal pump is responsible for rotating the liquid?
Impeller
How does the rise in pressure head in a centrifugal pump vary with the tangential velocity of the liquid?
It is proportional to the square of velocity
Which part of a centrifugal pump is connected to the shaft of an electric motor?
'Impeller'
What is the precaution against cavitation related to the pressure of the flowing liquid in the hydraulic system?
Maintaining the pressure above the vapour pressure of the liquid
What effects are observed due to cavitation on turbine blades?
Roughening of the surface due to pitting action
How is Net Positive Suction Head (NPSH) defined?
The pressure at the inlet of the pump minus the vapour pressure head plus velocity head
How is NPSH related to cavitation-free pump operation?
Available NPSH should be greater than the required NPSH
What distinguishes between the required and available NPSH for a pump installation?
Required NPSH is determined experimentally while available NPSH is given by the pump manufacturer
What materials are recommended as a precaution against cavitation?
Aluminium and steel
What is the main function of the casing surrounding the impeller in a centrifugal pump?
To convert kinetic energy into pressure energy
What is the purpose of a foot valve in the suction pipe of a centrifugal pump?
To prevent backflow of water from the pump
In a multistage centrifugal pump, impellers connected in series are used primarily to:
Produce high head
What is the main function of connecting impellers in parallel in a multistage centrifugal pump?
To increase pressure
Which phenomenon describes the formation of vapor bubbles in a flowing liquid due to pressure drop?
Cavitation
In a centrifugal pump, what occurs when the pressure of the flowing liquid falls below its vapor pressure?
Boiling
What action causes pitting on metallic surfaces due to cavitation in pumps?
Collapsing of vapor bubbles
What is the primary reason for connecting multiple impellers on the same shaft in a multistage pump?
To increase head.
What is the role of a strainer at the lower end of a suction pipe connected to a centrifugal pump?
Filter out debris.
Test your knowledge on hydraulic machines that convert mechanical energy into hydraulic energy, specifically focusing on centrifugal pumps which use centrifugal force to generate pressure energy. Learn about the reverse flow mechanism and characteristics of centrifugal pumps.
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