KALI CHARAN NIGAM INSTITUTE OF
TECHNOLOGY, BANDA
LECTURE
ON
CENTRIFUGAL PUMP
TOPIC – MINIMUM SPEED FOR STARTING A CENTRIFUGAL PUMP
FLUID MECHANICS AND FLUID MACHINE (KME302)
BY : DEEPAK KUMAR YADAV
ME DEPARTMENT

MINIMUM SPEED FOR STARTING A
CENTRIFUGAL PUMP
 If the pressure rise in the impeller is more than or
equal to manometric head (Hm), the centrifugal
pump will start delivering water.
Otherwise, the pump will not discharge any water,
though the impeller is rotating.
When impeller is rotating, the water in contact with
the impeller is also rotating, this is case of force
vortex.

MINIMUM SPEED FOR STARTING
A CENTRIFUGAL PUMP
 In case of forced vortex, the centrifugal head or
head due to pressure rise in the impeller
=
Head due to pressure rise in impeller =
 The flow of water will commence only if
Head due to pressure rise in impeller

MINIMUM SPEED FOR STARTING A
CENTRIFUGAL PUMP
For minimum speed, we must have ….(i)
Substituting this value in equation (i)

MINIMUM SPEED FOR STARTING
A CENTRIFUGAL PUMP
Substituting the value of and
Dividing by

NUMERICAL
PROBLEM 1: The diameter of an impeller of a
centrifugal pump at inlet and outlet are 30cm and
60cm respectively. Determine the minimum speed
starting speed of the pump if it works against a
head of 30m. [AKTU 2016-17]
SOLUTION: Diameter of impeller at inlet,
Diameter of impeller at outlet,
Head, Hm = 30m
Let the minimum starting speed = N

NUMERICAL
where

NUMERICAL
PROBLEM 2: The diameter of an impeller of a
centrifugal pump at inlet and outlet are 30cm and
60cm respectively. The velocity of flow at outlet is
2m/s and the vanes are set back an angle of 45o
the outlet. Determine the minimum speed of the
pump if the manometric efficiency if 70%.
SOLUTION :

NUMERICAL
 Let the minimum speed starting speed = N

NUMERICAL
• Put all given values on minimum speed equation,
we get

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