2 replies to this topic

[aika93]

Hello Dear Community Members!

 

I am fresh process engineer and confused with the name/title for pump power.

I have pump data sheet with different names for pump power, as absorbed, hydraulic, rated, installed.

Which one we calculate and which one is vendor to advice? Are this powers related with formulas?

 

 

Could you please explain and differentiate this for me?

 

Many Thanks and Regards,

Aika

[Chemitofreak]

Hi,

 

Refer the following link for description and formula:

 

https://www.engineer...ower-d_505.html

[Art Montemayor]

Aika:

 

You are a new, young engineer with what I presume is minimum process/project experience in the field.  I gather this from what you write, and it is quite typical of new engineers because of their lack of exposure or experience with real-life projects out in the field.  Being taught by strictly theoretical and academic-oriented instructors in university is sometimes a liability because of the failure to teach you what EXACTLY is expected of you and how you are expected to communicate and exchange engineering information when out in an industrial project.  Allow me to share some of my experience accumulated over more than 50 years practicing what you are facing.

 

First:  Always communicate what type of pump you are dealing with.  Don’t just simply assume everyone knows what you are keeping to yourself.  This is just simply good old-fashion horse sense.  I have to assume that you are referring to a centrifugal pump and not to any of the other types.

 

A Data Sheet is a document that is designed to document and communicate the basic, design, and existing engineering data related to a piece of equipment that is normally specified to - and purchased from - a designer/manufacturer of that equipment.  In this case, it is a pump manufacturer who needs vital information from you if the desired pump purchased is to function exactly as you want/need it to operate when installed.  The pump manufacturer is THE expert in this case and you have to feed him/her the required information that will allow accurate identification of the correct pump size and model required by you.  You are NOT the expert and should not meddle in the design - unless you want to take responsibility for the results.  You can calculate all you want to your heart’s delight, but those calculations WILL NOT enter into the ultimate pump design - not unless you want to take all the legal responsibility and ramifications that can develop from a bad design.  No experienced process/project engineer will ever do that, but if that is what you want to do, you are free to do so.

 

As the end user of the purchased pump, you should be interested in certain vital engineering information that you need for its successful installation and future operation: its size, weight, power requirement, physical characteristics, maintenance requirements, operation instructions, capacity curves, etc., etc.  This information is what the supplier should supply you with - some of it in the formal proposal.  The power requirement (electric motor size, speed, and hp) is determined by the manufacturer - NOT YOU.  You can oversize the driver if you wish, but I would always discuss this with the supplier or any other operational details - such as speed variation, flow variation, stop and start conditions, discharge head variations, or fluid characteristics.

 

You say you have a data sheet.  Why don’t you submit it so our members can see what it is that you are dealing with?  And what is the purpose of your calculating any power requirement?  The only power requirement that should be of interest to you should be what is quoted and that denoted in the characteristic operating curve for the pump - as per the manufacturer.  I am submitting my set of process data sheets for your interest (if any) and note that I am very free and candid with my information.  You should be more so, since you are the one requesting help.  Pay attention to the details that I have in my pump data sheet.  Note that I specifically denote the information (in RED fonts) to be supplied by the manufacturer.

 

Last item of advice: pump power requirements can be interpreted in many ways - most of them are theoretical or ideal conditions.  The actual, real-life hp requirement is the shaft horsepower required of the selected driver - and that should include not only the hydraulic head the pump must overcome, but also pump, gland, bearing, and other mechanical loads the pump may have (which you know little about).

 

I hope this information is of help to you.

 Arts Process Spec Sheets.xlsx   685.4KB   58 downloads