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Vertical mixed flow turbine pump selection

Vertical mixed flow turbine pump selection

(OP)
Hello Experts,

We are planning to buy and install VT pumps (seawater &15,0000 m3/hr capacity)through design and build contract. I would like to know the best practices in this field and the best brands and designs for the different parts of this pump.

I would like to know also the important stages in manufacturing these pumps and how to control quality.

This is the first time for me to buy this size of pumps and I will appreciate your assistance.I am hesistating to hire a consultant as I have some limitations.

Regards

RE: Vertical mixed flow turbine pump selection

Is the flowrate 15,000 or 150,000 M3h? And at what total head?

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.)

RE: Vertical mixed flow turbine pump selection

(OP)
It is 15,000 m3/hr and head is 35 m

RE: Vertical mixed flow turbine pump selection

15,000, 1 pump or shared by multiple pumps.

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.)

RE: Vertical mixed flow turbine pump selection

Seawater will need special materials - probably aluminium bronze on all wetted parts.

Anything else just pits or gets eaten in a very short time.

Unfortunately your comment "I am hesitating to hire a consultant as I have some limitations." usually means you or your boss is trying to do this on the cheap by using inexperienced junior engineers such as yourself. What are your "limitations"??

This is a serious and significant error and you will end up making some big mistakes which will cost far more than employing a consultant engineer with years of experience of such pumps and motors. You can't get what you need from the internet.

Look closely at the casting of the impellor and the QA associated with that. That's where the big issues happen.

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

RE: Vertical mixed flow turbine pump selection

LittleInch, you must have been reading my mind 😊.

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.)

RE: Vertical mixed flow turbine pump selection

(OP)
We already have exactly similar pumps and I have 8 years experience.

It is only one pump to be added to the manifold and I don't think need consultantndue to cost and scarcity of qualified consultants in my part of the world

RE: Vertical mixed flow turbine pump selection

So just buy another one of the same type. Makes life very easy.

You said "This is the first time for me to buy this size of pumps ", therefore we could only draw the conclusion that your experience in this area was limited.

Like I said - when cost stops you hiring experienced people to do work then expect more costs when it goes wrong.

I work on projects all over the globe as I'm sure many of the others on here do as well, so scarcity is not an excuse.

Do a search on this site for "vertical turbine pumps" and you'll find a lot of the information you are looking for. Go look at vendor websites and download their guides and brochures and do a comparison.

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

RE: Vertical mixed flow turbine pump selection

Experience seems lacking to me, you initially said pumps (plural) and first time to buy pumps of this size, you now say 1 pump and 8 years of experience. If you already have pumps running and with your experience, why suddenly do you need best practice, best brands and design and important stages of manufacture and quality control.

Contact the previous supplier / pump manufacturer or search the website of the major pump manufacturers - it's not rocket science.

Of course what you have highlighted is a complete lack of useful data with your original post for a pump unit that will be a minimum of something like 1700 KW drive.

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.)

RE: Vertical mixed flow turbine pump selection

Agreed; if you have an existing base of 8 pumps, and you're happy with them, contact that supplier with your new operating conditions. Reference existing serial numbers. Confirm if pump length desired on new pump is same as existing.

Then you're good to go. Why mess with what works?

RE: Vertical mixed flow turbine pump selection

No doubt, from performance, to maintenance familiarity, to spares issues, use the same pump! However, you asked for broad information and gave very limited information; hope you are more thorough when actually buying this pump.

If a duplicate is not available or the user is not satisfied with existing, that may build a case to get a new one.

Issues:
Materials: it depends on where in the world these pumps are as to material selection; different temps and salinities require different materials. Nickel aluminum braonze is probably the most used material for seawater but duplex stainless costs constantly fluctuate and can be a better option. Ask a metallurgist familiar with your area.

Construction: You are on the border of a mixed-flow design; usually up to 100-120 ft head. Check these out online.
Lineshaft and bearing configuration:
Is this deep-sea or near shore;i.e. is there much sand in the content? If so, you really need to look at bearing/lineshaft design. With any sand you should have enclosed lineshaft with a good "sand" or bottom bearing. You will also need to consider how to lubricate enclosed bearings, again especially the bottom bearing.
How long will the lineshaft/column section be? Sounds like shortset ( <10') If so make sure everything is SS, flanged and SS bolting.

As far as manufacturing, checking the impeller casting certs could be important, as well as for balance. Will you go with just bowl rings, or both bowl and impeller?

So many more things to go through before making a prudent selection. This is why it is not a good idea to try to design one of these on the internet. If you are not going to consider a consultant, talk to a reputable manufacturer and get their opinion. Most of them don't bite.

RE: Vertical mixed flow turbine pump selection

(OP)
I find most of the comments smell arrogance and don't include useful information. I never mentioned that we have 8 pumps!

We have three pumps already on the same manifold and after several years we wish to install additional one.Of course, I have all information of previously installed pumps and feedbak of the operator. I am just writing in this forum to get more advises and may be an update about latest designs or technologies. I didn't write here to get scolding.

Nevertheless, many thanks to whoever replied to my post.

I really appreciate DubMac who invested his time in writing good advise and recommendations. Thank you DubMac.

RE: Vertical mixed flow turbine pump selection

Omneng,

You may be right - we were being a little obtuse, but to avoid it the next time, I would recommend the following:

1) Make it clear in your OP what your situation is and why you are looking for information
2) Do some work beforehand to investigate or search for information. E.g. in your case you could have said, "Our current pumps are made by "X", I have also found similar pumps made by "S", "T" and "G". Are there others worth considering or any feed back on experience of those vendors would be very useful". There are a lot of posts here which are very broad and say things like, "please teach me all you know about pumps". Far far too broad a subject for an internet forum
3) Be as precise as you can and give as much information as you can - you were ok in terms of flow and head, but location makes a difference
4) remember all the posters do this for free and in their spare time, so cut them a little slack.

Hope you got a bit of useful information, but if you get something a bit more specific, come back and also let us know what you chose / did afterwards.

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

RE: Vertical mixed flow turbine pump selection

I wouldn't say we were being obtuse, we certainly aren't dull - seems more like trying to gleam meaningful data.

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.)

RE: Vertical mixed flow turbine pump selection

This is a high volume pump. To be fair to everybody who posted here they in their own way are providing you with good advice. You could be out of a job if you screw this up and you could wind up with an ulcer learning about pumps pretty fast after it has been destroyed. There is a lot of money involved if you screw up. Water can cause a lot of damage. Do not take this lightly. Hire a professional engineer who has done this type of stuff before. Don’t try to be a superman. Know your limitations. Learn from an experienced engineer by working with him. Shadow his thoughts and bounce your thoughts off him. This is good advice.

Copying an existing pump can also be a recipe for disaster if you have not checked the hydraulics on the system

I think what is irking everyone here is that it is perceived that you (and your superiors) have no engineering experience and you are asking experienced engineers on this forum for advice to minimize costs by doing it yourself. It is like you asking a bunch of doctors for tips on how to do a heart transplant by yourself because your neighbor had one done on him and it was successful. There is more to it than meets the eye and because of the ramifications nobody wants to get involved with you. You have to have some basic knowledge of pumps to gain from the benefits that this forum can provide. I could be wrong but it seems clear that you do not even have the basic beginner’s knowledge of where to even start. I truly hope I am wrong in what I said. Good luck

RE: Vertical mixed flow turbine pump selection

Responders missed the key word in the original post- first time to do this SIZE of this type of pump (Not first time to do this type of pump). A magnitude up or down can be significant I do 1000 barrel/hr and this new application need 10 barrels/hr. Careful reading would have saved a whole heap of hassles.

http://www.eng-tips.com/threadminder.cfm?pid=1529
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RE: Vertical mixed flow turbine pump selection

Think we did read it and just for clarification it was " first time for me to buy this size....". What would have saved a lot of hassles would have been clear information initially.

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.)

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