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Centrifugal Pump Electrical Power Demand & Consumption

electrical power demand consumption centrifugal pumps

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#1 Sherif Morsi

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Posted 11 July 2019 - 01:22 PM



In the plant, we have a propane product pump continuously running. The following data applies to the pump:

delta P: 143.6

Hyd power: 72.6

E: 78.5% (as per the pump curve)

BHP: 92.48 hp


The pump is run by a 150 HP motor.


How much the power demand? would it be equivalent to the BHP + losses due to the shaft and electrical motor efficiency?


How can I estimate the losses in the shaft and the electrical motor?




#2 Bobby Strain

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Posted 11 July 2019 - 04:09 PM

This should provide what you need.



#3 Chemitofreak


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Posted 12 July 2019 - 12:46 AM

Hi Sherif,


I would suggest you to have a word with an Electrical Engineer in your company. We don't know the make of the motor, which can have an impact on actual power consumption.



#4 thorium90


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Posted 12 July 2019 - 01:31 AM

Actually, if the pump is already installed, why not read the power off the power meter? Or if there isnt a power meter, a clamp on power meter can also be used.

Why do theoretical estimates when the pump is already running there, continuously?

What is the reason for calculating this power estimate?

Edited by thorium90, 12 July 2019 - 01:32 AM.

#5 Sherif Morsi

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Posted 12 July 2019 - 09:06 AM

Thank you all.


@thorium, can you elaborate more on these clamp on meters? I checked them online but how do they work? Can you just install them without shutting power down? 

#6 PhilippM


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Posted 12 July 2019 - 01:08 PM

There is an entire Wikipedia article about these clamps that should give you all the information needed to understand them:



#7 Art Montemayor

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Posted 12 July 2019 - 09:17 PM

I am quite surprised that any engineer - mechanical, chemical, or industrial - working in a processing plant does not have knowledge or experience in using what we old timers used over 60 years ago.  The instrument was (and still is) called an Amprobe.  Go to:


and get a first hand look at what they look like and get one of their catalogs.


You do not need an electrical engineer to use this instrument nor to calculate the motor's electrical load.  Read the article that Bobby Strain recommends.  You must understand how alternating electrical current works and how it is applied and measured - especially the existence and workings of a Power Factor.  I believe that is why Bobby has pointed out this fine article.   We old time Chemical Engineers had to take Electrical Engineering courses and labs where we learned this stuff.  I took two courses before senior year and used my first amprobe in my first job out of college.  I thought every ChE knew this stuff.  I certainly would expect them to.


As a plant production manager I always expected my project and production engineers to use this instrument and always have access to one.

#8 Sherif Morsi

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Posted 31 July 2019 - 08:40 AM

Thanks for your feedback Art.


I just started working in the plant 6 months ago and between walking out to familiarize myself with the operations/process and scoping/delivering projects as expected from superiors, I haven't had the chance yet to check into all the tools/skills that I would need in such environment. P.S: This is the first time I work in such an environment

#9 PhilippM


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Posted 31 July 2019 - 03:18 PM

No offense, but knowing about clamp meters isn't exactly special knowledge that's usually acquired by working in a process plant for quite some time.

That's general knowledge that is taught in Electrical Engineering 101.

You can buy those clamp meters in a hardware store for <50$

#10 Bobby Strain

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Posted 31 July 2019 - 06:43 PM


        You must learn to use the resources available to you. The most valuable of which is people. That's more valuable than trying to know everything about everything.


Good Luck.


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