Exam Question
(a) Describe why priming is required for centrifugal Pumps, With diagrammatic sketch describe working of Primer for centrifugal pump. (10)
(b) Why balance holes are provided in the impeller? (6)
Class 4 (4th Engineer)
MEP
📅 Apr 2023
Reference Answer
### (a) Priming of Centrifugal Pumps and Working of a Primer (10 Marks)
#### **1. Reason for Requiring Priming**
Priming is the process of filling the pump casing and suction line with the liquid to be pumped before the pump is started. Centrifugal pumps are non-positive displacement machines and are not inherently self-priming. The requirement for priming is based on fundamental fluid dynamics principles:
* **Operating Principle:** A centrifugal pump operates by imparting kinetic energy to a fluid via a rotating impeller. This kinetic energy is then converted into pressure energy in the volute casing. The pressure head ($$H$$) generated is directly proportional to the density ($$\rho$$) of the fluid being pumped, as shown by the formula $$ \Delta P = \rho \times g \times H $$.
#### **1. Reason for Requiring Priming**
Priming is the process of filling the pump casing and suction line with the liquid to be pumped before the pump is started. Centrifugal pumps are non-positive displacement machines and are not inherently self-priming. The requirement for priming is based on fundamental fluid dynamics principles:
* **Operating Principle:** A centrifugal pump operates by imparting kinetic energy to a fluid via a rotating impeller. This kinetic energy is then converted into pressure energy in the volute casing. The pressure head ($$H$$) generated is directly proportional to the density ($$\rho$$) of the fluid being pumped, as shown by the formula $$ \Delta P = \rho \times g \times H $$.
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