Pump Hydraulics an Introduction

Pump Hydraulics an Introduction

Let me tell you a story to begin with..

Once upon a Time, ABC Company has just won a bid for a lube oil pipeline transfer Tender.

Mike  the Manager and John his Junior are tasked to the design work.

They have the experience in handling the water pipeline transfer projects.

But due to the company’s restructuring, now they have been tasked to do this lube oil pipe design

John, being the junior is unsure whether his estimates are correct.

But Mike advises him not to worry and liquids will not play a major role in their calculations. I will let you know what happened to John and his calculations.

But let me ask you a question first:

Does a liquid property really influence the pump /pipe/system design?

Good Day Everyone

This is Karthik and Welcome to the Pump Hydraulics – An Introduction.

First Things First

A quick overview of what we are going to discuss today.

Firstly, What is pump hydraulics. What is this session all about

Secondly, the operating principle of Centrifugal Pumps

Then, the pump components responsible for pump operation

Liquid conditions that impacts the operation of the pumps

Finally, learn a bit about the Cavitation, it’s impact and why NPSH ( Net Positive Suction Head) is important.


Conclusion of John’s story

John learnt it the hard way that SG and Viscosity are key to his calculations as his design and actual requirement were poles apart.

Now the question to you :

What are the other liquid characteristics that you need to know prior to sizing up the pump ? ( Pause for few secs for answers)

Pop in your answers in the comments section

I see Temperature and other nature of liquids . That’s right. We are going to see how they impact in detail.

What is Pump Hydraulics ?

In a way , this exercise or the process of understanding the liquids, its chemical properties, physical properties and how it impacts the pump operation is what is called the pump hydraulics.

It is a science that deals with physical and chemical properties of liquids and its relationship with the pumping.

Two Types

Based on the response that the pump gives to the liquids , they are classified as Hydrostatic and hydrodynamic pumps.

Hydrostatic or the constant volume pumps maintains its volume in a fixed speed operation regardless of the change in pressure due to various factors .

The factors could be system issues, change of liquid properties etc.

E.g. Of this pump type could be an internal gear pump as shown in this screen right now.

Hydrodynamic or the variable volume pumps adjusts its volume in a fixed speed operation.




In the next session, we are going to discuss about the centrifugal pump operating principle,pump components and things to notice in a performance curve.

If you would like to listen to this segment, the above link is for you to understand the concept a bit better. 

Image Credits :
Getty Images - Vapour Pressure, Specific Gravity and Viscosity
Pump Operating Principle - Licensed under CC by NC 2.0

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