Article Contents
Characteristic curve of pump is a important chapter for chemical or mechanical engineer or those who are working as project or process engineer.If you don’t have idea about pump like what is pump? What are the different types of pump? What are the different types of Centrifugal pump? How Centrifugal pump work? Types of positive displacement pump? You can read my old post on it. In today article we study only characteristic curve of pump.
characteristic curve of pump
Characteristic curves of a centrifugal pump are nothing but curves which give information about pump flow, head power requirements and NPHH requirement.
The main characteristic curve of pump are as follows.
- Flow vrs Head
- Flow vrs Power
- Flow vrs NPSH
- Flow vrs efficiency of pump
Befor to study about performance curves of centrifugal pump we need to have some basic information. What is pump shutt of pressure?
What is shut off pressure?
Shutt of pressure is nothing but maximum pressure developed by a centrifugal pump when pump outlet valve is closed.
In other words shut off pressure is maximum pressure of a pump at zero flow or no flow.
What is Pump efficiency
Pump efficiency is very important in economic point of view.Pump efficiency is nothing but ratio of pump input power to pump output power at our requirement condition.
Example :- If our required flow is 30 M3/hr and head is 40 M then we need to check what is pump efficiency at this flow and head by pump performance curve.
Power Required to Pump the liquid
we can calculate the power required to pump the liquid by pump characteristic curve or by calculations.
Power required in KW = (Head * flow * density*g/36 X 10^5 ) / efficiency
Pump performance curves
Flow verses Head /Pressure
Pump flow verses pump head is very important characteristic curve of a centrifugal pump. A pump can give high flow at low head or high pressure at low flow. As per process requirements we need to check the pump flow verses pump head curve.
Pump flow verses power requirement
What is BKW in Pump?
BKW in pump is nothing but pump brake power, it is actual power used or delivered to pump for pumping the liquid.
Pump flow verses power is another performance curve of pump. When we increase the flow we need more power to pump the liquid.Following figure is best example of pump flow verses pump power.
Flow verses NPHS
NPSH is nothing but net positive suction head required to avoid the capitation in pump. There are two types of NPSH one is NPSH Available and second is NPSH required.
For more details please study our article on NPSH of pump.
follwing pump performance curve of a centrifugal pump give us idea about for more flow we need high NPSH available. We can increase the flow or head by increasing NPSH available.
Flow verses efficiency
Flow verses efficiency is very important pump characteristic curve. In general pump with low flow gives low efficiency.
What is pump BKW? What is pump shutt off pressure? What is pump efficiency??.
Conclusion
This article explain how pump performance curve is important while selection of pump as per our process requirements. We need check our required head, flow, pressure as per pump characteristic curve. I Hope above information is sufficient for you to get idea about centrifugal pump characteristic curve. From above article you can able to calculate pump power requirement too. As long you can find the pump efficiency as per requirement.
Thank you for Reading…….
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