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.

 

[shvet]

i have one doubt in it because it shows only 64.7% efficiency

why can't i get 90% efficiency?

i don't know how the term efficiency used

You mean, you are asking for efficiency and you don't know the term "efficiency" means? I am asking how to cook pancakes and I do not know what pancakes are. Will my guests like at the end what I cook?

term efficiency means the quality of a machine by its output with respect to time

"Output vs time" characteristic means "capacity", it is not able to mean "efficiency". "Efficiency" means ratio between input and output power, nothing less and nothing more.

Can you describe your role&background in this project?

 

[Asisraja D]

shvet sir
Can you describe your role&background in this project?

i am a mechanical project engineer. it is a greenfield project so i am responsible for verifying utility related pumps & equipment erection without any error with required specification of already designed data through another consultancy services. right now i am involving myself in getting quotes from vendor's and making comparative for them. i confused when i noticed the term efficiency is less compared to our previous purchase because i we purchased 180 m3/hr pump with 45 meter head before, that's why i confused with the term efficiency. please reivew the purchase order that we have already purchased last time.

"Strive for perfection in everything you do. Take the best that exists and make it better. When it does not exist, design it." - Sir Henry Royce

 

[LittleInch]

Like we're all saying, and that's a great graph by shvet, you're comparing apples with oranges here.

A 30m3/hr 25m head 3 kW pump is a different beast to a 180m3/hr 45 m head, 30kW pump.

Hence the different efficiency.

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

 

[Asisraja D]

LittleInch sir
Thank you. now i am clear in this but anyhow i will have to practice reading pump curves basics.

"Strive for perfection in everything you do. Take the best that exists and make it better. When it does not exist, design it." - Sir Henry Royce

 

[pierreick]

Hi,
To estimate the efficiency of a pump, instead of using a curve, you may want to use this correlation where:
Eff= Pump percentage efficiency,
F developed head, ft
G flow, GPM
valid for F 50-300 ft; G 100-1000 GPM

Eff=80-0.2855*F +3.78E-04*F*G -2.38 E-07*F*G^2 +5.39E-04*F^2 -6.39E-07*F^2*G+4*E-10*F^2*G^2

Correlation published in Rules of Thumb for Chemical Engineers -Carl Branan, based on data from manufacturers and GPSA curves.
With your figures I got 63.4% efficiency .
This should help you and clear your doubts.
Pierre

 

[Asisraja D]

pierreick sir
Thank you

"Strive for perfection in everything you do. Take the best that exists and make it better. When it does not exist, design it." - Sir Henry Royce

 

[Asisraja D]

pierreick sir
I used this correlation for a pump with flow rate : 22.01 GPM and Head : 82.02 Feet. it gave me 36.4% but i got this value in negative anyhow the efficiency meets the same as the vendor provided Eff 35.2%.

"Strive for perfection in everything you do. Take the best that exists and make it better. When it does not exist, design it." - Sir Henry Royce

 

[pierreick]

Hi,
Check the range of flow prior to use the correlation.
Note :35% is very low but.... very small pump.

Pierre

 

[LittleInch]

It's still only 1kW....

This is like a domestic heating pump....

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

 

[Asisraja D]

LittleInch sir
This is like a domestic heating pump.

we use this for just 2" header for hot water circulation purposes.

"Strive for perfection in everything you do. Take the best that exists and make it better. When it does not exist, design it." - Sir Henry Royce

 

[Asisraja D]

pierreick sir
I checked the flow rate. it is same as we required. thanks for your calculation

"Strive for perfection in everything you do. Take the best that exists and make it better. When it does not exist, design it." - Sir Henry Royce