Self-learning on Pump Application

Introduction

•Pumps are devices that help us to move liquids from a place to another.
•Pumps are dated back as old as Romans times.
•Pumps changes our way of transfering liquids.
•We can see pumps everywhere in our daily environment.

Basic Pump Theory

•Volume Flow Rate: V=AC
•Continuity of Flow: V1=V2
•Reynolds Number: Re= ρdC/μ
•Friction Factor: ƒ = 64/ Re
•Friction Loss: hƒ= fL/d . C²/2g
•Minor loss: hm=K.C²/2g

Series and Parallel Pumps:

•Therefore, pumps in series caused increase in pressure but no change in discharge. However, parallel caused increase in discharge but no change in pressure.

TYPES OF PUMP

Centrifugal Pump
•Covert mechanical energy into hydraulic energy
•Usually over-sized
•Different kind of designs

Applications
•Found in almost every industry and domestic services

Maintenance
•Wear internally
•Depend on material, speed of liquid, heat and contamination

Swash plate pumps
•Rotating cylinder containing piston
•Piston moving front and back
•Angle of swash plate varies
Applications
Use for wide range of application

Maintenance
•Ensure blade work properly
•Depend on speed, heat, and contamination.

Air lifts pump
•Air compressor
•Mixing with air
•Can rise 20 to 2000 gallons
•Rise up to 750 feets
Applications
•Use to pump out mixture out of mine

Maintenance
•Lubrication not much needed


NPSH

•Net Positive Suction Head
• Difference between the Suction Head and the Liquids Vapour
• Suction head in the fluid close to the impeller is the sum of the static and velocity head.
• hs = ps / γ + vs2 / 2 g
• Liquid Vapour Head
•hv = pv / γ
•Therefore NPSH formula:
• NPSH = ps / γ + vs2 / 2 g - pv / γ

NPSHA and NPSHR

•NPSHA or Net Positive Suction Head Available
•NPSHR or Net Positive Suction Head Required
•NPSHA determined during design and construction or can be also derived from the actual physical system.
•NPSHR required by the pump in order to prevent cavitation for safe and reliable operation of the pump
•NPSHR for a particular pump is in general determined experimentally by the pump manufacturer and a part of the documentation of the pump.

Cavitation

•The process of bubbles forming then collapsing violently
•Occur in two different forms
•Suction Cavitation
•Discharge Cavitation

Suction Cavitation
•It occurs when the pump suction is under a low pressure/high vacuum condition where the liquid turns to vapour at the eye of the pump impeller.
•The vapour is then carried over to the discharge side of the pump where it no longer sees vacuum and is compressed back into a liquid by the discharge pressure.
•This violently results in removing large chunks of material from the face of the impeller.
•This cause premature failure of the pump.
•It is identified by a sound like gravel or marbles in the pump casing.

Discharge Cavitation
•It occurs when the pump discharge pressure is extremely high.
•Occurring in a pump that is running at less than 10% of its best efficiency point.
•Majority of the fluid circulate inside the pump instead of being allowed to flow out the discharge when the pump discharge pressure is high.

Tribute:
This is research e learning is done by Alvin, Aziz, Kenny and Kenneth. All information is presented and for reference only.