Need help in pump specification details 2

[Asisraja D]

Hi
i have asked to get the quotation for the below specification for vertical inline pump (Centrifugal pumps) and vendor shared me a quote but i have one doubt in it because it shows only 64.7% efficiency. i don't understand why it shows less efficiency, can anyone please explain me a bit about this ?
i shared the vendor quote here with specification.



Thanks for all for helping me.

 

[1503-44]

Probably because it is a cheap design.
High efficiency ALWAYS costs more money, but you can save that extra money in future power costs.
If you buy the low bidders offer, be prepared to buy the lowest efficiency pump and pay for future power consumption.
If you have a cheap power supply, maybe you can use that low cost pump.
If your power supply is expensive, high efficiency is the way to go.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[BEMPE16524]

what the vendor said?

R.Efendy

 

[Asisraja D]

The vendor says it is based on the software they use in their system for their products. It shows whatever the efficiency for the specified flow rates when they applied to them.

 

[BEMPE16524]

have you compared with different model/brand? then probably you can guess why.

R.Efendy

 

[Asisraja D]

BEMPE16524 not yet. waiting for another vendor quotation for comparing technical specifications.

 

[Asisraja D]

For more details i have attached the vendor quotation file here

 

[LittleInch]

"i don't understand why it shows less efficiency, "

Less efficiency than what?

These look like simple Cast /iron pumps and at that size 65 odd % efficiency is a bit on the low side, but not unusual.

Up to you whether to buy them depending on the other options and how often these pumps run.

#running >80% of the time then efficiency over 20 years operation adds up to a lot of kWh. Run <25% of the time then it doesn't.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Asisraja D]

LittleInch sir
i used the word less means why can't i get 90% efficiency? is this achievable through right selection ? or else any basic understanding in this ? please share your valuable knowledge

 

[LittleInch]

90% pump efficiency???

You clearly have never seen a set of pump curves before now, especially for such piddly little pumps ( 30m3/hr, 25m diff head, 3-6 kW cast iron pumps).
I would be very surprised to see this type of pump being more than 75% efficient and up to 70% is probably about as good as you're going to get.

Large, high volume, high pressure pumps can reach 80%+ efficiency as a Best Efficiency Point (BEP), but you're a loooooong way from that sort of pump here.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Asisraja D]

LittleInch sir
So there is no any common efficiency point for deciding a pump as best to suit for any application ? it varies based on capacity.

 

[LittleInch]

It varies by capacity, manufacturer, type of pump, fluid, design of the pump internals, type of bearings etc.

A "normal" range for this sort of pump I would expect is 60 to 75%. Anything lower is a bit low, anything higher would normally cost a lot.

For smaller pumps fixed losses or things which don't change much such as losses due to bearings, seals, stuffing boxes etc have a bigger impact compared to larger pumps so overall their efficiencies will be lower.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Asisraja D]

LittleInch sir
Thank you so much for your help. and i shared another vendor quoted for the same specification. As you told they gave efficiency for the margin from 60 to 65 % only.

 

[LittleInch]

Yup.

Does that answer your question / query?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[pierreick]

Hi,
Did you check with other vendors? At least 3 proposals are required to perform a comparative analysis including Technical/ CAPEX,OPEX.
What was written in your specification sheet about efficiency? I don't know what you are expecting!
Note: Your pumps are very small, not really relevant to me. Again, calculate and compare OPEX.
The vendors selected are reputable.
Good luck
Pierre

 

[Artisi]

Your question has been answered, for a standard mass produced pump of this size, the efficiency quoted is in the right ball park.
For higher efficiencies you need to be looking at much larger well engineered pumps built to exacting standards, and yes you can get to 90% plus but certainly not at the performances your discussing.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[BEMPE16524]

even if you have such high efficiency pumps, the real performance may not as what you expected because the ideal/lab test is totally different from the real operation.
So, you can only refer to your pump curve and decide at which point you want to operate and consider all factors into account when selecting the operating point.

R.Efendy

 

[shvet]

What is a problem? Why are you focused on efficiency? Why power consumption is important for this small low-power pump? You have no 2-3 kW power supply spare? Or is this a demonstration pilot plant intended to persuade investors to buy a venture during IPO so the every nut shall shine perfect?
Did you compare power cost to others like interest on investments, costs of maintenance, spare parts and many many others?
Note that such "inefficient" pump is able to be robust and require no inspection, maintenance, parts replacement and similar operating costs and therefore be attractive to an operating team as requires a little attention.
Note that an engineer usually has little understanding of money and how to spend/earn it efficiently.

For reference see:
- ANSI/HI 20.3 Efficiency Prediction
- HI Pump Life Cycle Costs Guide

 

[Doug Hunter]

The efficiency of centrifugal (dynamic) pumps will drop significantly with increasing pressure. If you want higher efficiency, you could look at displacement-style pumps.

Best regards,
Doug Hunter
Altarium Technical Consulting

 

[Asisraja D]

shvet Sir
i don't know how the term efficiency used here around pump terminologies especially for this centrifugal pump because the term efficiency means the quality of a machine by its output with respect to time generally. Yeah i don't want to generalize here the talking but i think i will have to gain some knowledge in this. thank you sir.