Finding correct pumps

[Zonked]

Hi!

I’m trying to find the right pumps for a heating medium and cooling medium system.
We have the required flow rates, temp variations and power needed for the pumps,
but we don't have the actual pump weights and a specific pump product from a supplier.

Centrifugal Pump 1
m³/h 1600
kW 430
Density: about 960-750kg/m^3
Temp: -14 up to about 300 degrees Celsius (Thermal oil)

Centrifugal Pump 2 to the expansion tank
m³/h 40
kw 5
Density: about 960-750kg/m^3
Temp: -14 up to about 300 degrees Celsius (Thermal oil)

Centrifugal Pump 3 (This one is pretty large and there is 3 of them paralleled, considering series)
m³/h 4300
kW 2000
Density: 1000kg/m^3 water

Centrifugal Pump 4
kW 50
m³/h 500
Density: 1000kg/m^3 water

Centrifugal Pump 5
kW 200
m³/h 950
Density: 1000kg/m^3 water

We are most importantly trying to predict the weight of the pumps by finding data on specific products that qualifies.
Does anyone have tips on where to find the actual product that fits with this data?
We managed to google lots of data on the electric motors for the pumps, but not as a centrifugal pump "set".
And asking suppliers as students can be kind of weird since we aren't actually going to buy a product.

Our project assignment is not that specific. Our group is responsible for the machinery (expansion tanks, filters, pumps and heat exchangers).
We have lots of P&ID's and have managed to size the expansion tanks which was actually pretty simple.
We have about 6 weeks to do this.

But maybe I'm going about this the wrong way. I think I should be able to calculate
the size and weight of the pump and shaft by not being lazy and using my brain for a second.

So we have three ways to do this:
1. Get the info from the company that gave us the project.
They actually said they would act as a supplier, but since they gave us most of the data
needed for a supplier to predict a product it takes away the challenge as I see it.
Then I couldn't possibly think of why we would deserve a good grade on this.
2. Ask an actual supplier; get "contacts" on our own.
3. Calculate the pumps dimensions from the ground up.

How would you guys think and go about when working on this as experienced engineers?

 

[Artisi]

Simple, you contact one of the bid pump companies and ask for the sales department. Explain your requirements and ask for a catalogue / or link to their website so you can make some pump selections, once you have completed the pump selections you then need to look at the pumps physical data for weights, configuration and dimensions.
For the larger units these may not be catalogued and could / would be special order - you will then need to get friendly with the sales guys / gals and ask for assistance.

With the proper pump data in front of you - probably about 10 minutes per unit for selection and compiling data.

No real challenge, just another job to be done along with the many other things an application engineer would face in a day.

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.)

 

[Artisi]

Read big not bid pump companies.

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.)

 

[Zonked]

Thanks Artisi, i have found many of your posts helpful.

I just did what you said(like a pro businessman), if this works I will buy a cigar!

 

[cvg]

designing a pump, given a target flow rate without having any knowledge of the piping system it will tie into is a bit problematic. for one thing, I do not see any pressures listed. I guess you could assume an efficiency and back calculate the pressure, but that would not be how it is generally done in practice. since you are specifying centrifugal pumps, I would expect a range of flows / pressures as it will be difficult at best to hit a very specific target flow rate.

 

[LittleInch]

Also remember it's differential head that the pump vendor wants to know. If some of these are high flow, low diff head pumps, you might need something other than a centrifugal and perhaps more like an axial or mixed flow pump, but differential head, flow and Sg are the really crucial things a vendor will look for.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Zonked]

Right. And assuming an efficiency for the thermal oil is probably even more difficult because of the unknown viscosity in the various temps? I will just have see what kind of answer I get.

 

[TenPenny]

If I understand your question, you're trying to get an approximate weight for pumps that will do this job.

For that level of detail, have a look at the attached brochure, there are curves in here for the various sizes; if you look up a pump that will hit the flowrate you're looking for, near the back you'll find a list which gives the dimensions and weights for the various sizes. Should be good enough for what you're doing.

 

[DubMac]

And another thing........

One of first things an Application Engineer will do when he gets your request is to separate your 5 services according to the pump type, or configuration. This is a judgement call on his/her part and depends MOSTLY on the GPM and the TDH. With your HVAC services listed, he'll mostly likely find a couple of radial split end suction pumps, a few axial split double suction pumps (splitcases), and maybe a vertical pump or two.

Once he has selected the pump configuration/model for each service; pretty much the computer selection program takes over and overall weights are easy to get. The point is, the initial selection of the pump configuration can change the overall WEIGHTS by several factors, one way or the other. So hopefully your professor has figured in a margin of error of 4 or 5 for your exercise. If not, send him to this forum and have him explain him/herself.

This is the way it happens in the real world, I assure you. The best lesson you can learn from this school exercise is that there is still a shred of human creativity required in the pump selection process. Unfortunately, keystrokes will eventually replace that creativity.

 

[Zonked]

Tenpenny:

Right now the weight is the highest priority,
so that the structure people can do their thing.
Still, finding an exact pump is certainly not wrong.
The document is great, but it doesn't seem to cover the larger ones?

It seems that when you reach the 500kw mark the
googling market of pump data doesn't seem that thick.
The way I understand it is that the larger 2000kw pumps is pretty specialized.
I have managed to "calculate" some very rough weight numbers and that will have to do for now.
You would laugh if you knew how I did it.

DubMac:

Well that is some great info. What I haven't realized is the research that needs to be done before one selects a pump.
I can be the application engineer to a certain extent. Draft the different types of pumps in my thesis (pros, cons)
and find out what kind of specifications I need for the ideal pump for my system(not going into dim and weight).
Then go to the project company and ask for the specific pump, and hope that the pump I had in mind
is the same kind as theirs. If it isn't, I will try to explain to my professor why I did it differently.
I'm going to do some research on the different types and configurations you mentioned. Try to be creative.

As I kind explained in my first post, my problem is not that specific, which felt like the biggest problem.
Really, thanks for all the support everyone! Made this a lot easier for me to approach.