Vertical pumps Showing lower individual consumption when working in parallel than when working alone 5

[Romesff01]

System - Take water from a well both pumps connected to a collector and booster pump to take water to destination.
Initial intention by building a collector - to increase the caudal of water at the end location and increase pressure at booster pump.

Why do I have a difference of consumption when using 2 vertical pumps in parallel?
Does it has to do with a collector not being well dimension?

 

[Romesff01]

When I arrived in the company the system was already there, and that's the reason why is hard for me to give data on the same.
Because something seem weird that's why individually I decided to investigate.
End result I am hear hearing what all of you have to say about it, so I can pin point exactly what´s wrong in this picture.

Once appreciate all help and knowledge you guys have been giving on these case, I will see if I can get the tags on the pump-motor



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We need a sketch of your system showing where the pressures are measured.
The actual head in meters between the water level in the well and the point where the pressure readings are taken will also help.
If possible send us the following information:

 

[Romesff01]

Actually 3 pumps not 2.
However system is works only with 2 since with the 3 pump-motor there is no significant gain.
The 2 working pumps are identical the one not operational is different.
About degraded, we dealing with very old pump-motor, so a little degradation from both is expected.

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electricpete (Electrical) 8 May 19 21:53

Good analysis and questions by waross

op: another things I was wondering:
You have two pumps in parallel and they're drawing substantially different current.
Are these parallel pumps and motors supposed to be identical in design?
If so, then obviously the difference in current is not expected. Suggests most likely one of the pumps is degraded.

 

[Romesff01]

Agree.
However like you said VFD is expensive.
I was actually thinking on analyzing the system, there may be something it can be done in order to improve the situation.
I will see if I can get more information about:
1. System
2. Pumps
3. Motor



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waross (Electrical) 9 May 19 00:30

Romesff01;
A proposed solution.
First let me mention again my similar problem.
The head was approximately double after the change

 

[itsmoked]

Romesff01; You've never said what the HP or kW level of the motors are. (At least that I could find.)

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Romesff01]

Hi guys,
Sorry took so long like I said it was not easy finding information about these pumps
They are really old, documents are almost none existent and the few docs I found were images and I can´t barely read.

Vertical
Discharge pressure: 40 kg/cm2
Suction pressure: 8,8 kg/cm2
Diferential pressure: 31,2 kg/cm2
Total Head: 92,5 m
Capacidade: 200 m3/h
RPM: 3550
Recorded Drive Rating: 100
Pump Type: 6 OL 85

Horizontal
Discharge pressure: 40 kg/cm2
Suction pressure: 8,8 kg/cm2
Diferential pressure: 31,2 kg/cm2
Total Head: 312 m
Capacidade: 200 m3/h
RPM: 2960

I believe everything here is correct with the image I found, can´t be 100% sure.
Like I said assume both group pump-motor are the same
Still haven't found information on the third group

 

[waross]

Expletive deleted!!
Both the vertical and the horizontal pumps have the same rated capacity (200 m³/h) at the same differential pressure (31.2 kg/cm²).
BUT the vertical pumps are rated at 3550 RPM, a common 60 Hz speed.
The horizontal pumps are rated at 2960 RPM, a common 50 Hz speed.
This information should be on plates on the motors. Hopefully the plates are still there.
If the vertical pumps are operated on 50 Hz, the differential pressure will drop from 31.2 kg/cm² to 21.7 kg/cm².

If the horizontal pumps are operated on 60 Hz the power demand at rated conditions will increase to 173%.
What is your frequency?
With generator power, are you running both 50 Hz and 60 Hz?
Further to Keith's comment, can you find the rated HP, or rated Amperes.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Romesff01]

Hi
50 Hz
Cannot read the plate like I said before lack on information.
This data I got from a photo I found and I can barely read it.
I will keep looking for more information but we dealing with very old pumps