pump sizing 3

[optimomech]

I am an engineering protégé at one consulting company, my mentor gave a project to design a vertical turbine pump for a fire fighting system. I have desired requirements, capacity 1585 gpm and a pressure head 400 ft, according to VTP performance CURVES:
1. I chose pump performance curve that develops 1585 gpm at a head of 30 ft, number of stages =14, operating at 1760 RPM, efficiency=81% &BEP 82%.
2. I chose pump performance curve that develops 1585 gpm at a head of 100 ft, number of stages =4, operating at 1760 RPM, efficiency=79% &BEP 85.5%.
Which pump would be suitable for the system?
Thanking you
No knowledge is useless
John

 

[handleman]

If this is really for a fire suppression system, I would imagine there are a lot of codes/laws you need to follow in your particular country. If your mentor is truly a mentor (a word that implies responsibility training and instruction) he/she is the best person to talk to about this.

-handleman, CSWP (The new, easy test)

 

[Artisi]

John:
Beside the many other factors that must be considered for a fire pump, I would opt for the 4 stage unit. Also, when looking at the pumping efficiency you need to de-rate each stage from its published performance, the re-rate is usually shown on the curve.
You also need to know what code this pump must comply with and then carefully read the code until you have a full understanding of its intent / requirements.

If your mentor knows what "mentor" means then this should have already been discussed and clear direction given on how, when, where, why etc you should approach the problem - having to ask here in Eng-Tips seems to indicate you have been left high and dry to fend for yourself, but never fear, there are some good mentors in ET.


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.)

 

[optimomech]

He gave me some codes: Risk Class C -flow rate 1585 gpm, minimum running pressure at hydrants shall be 200 ft. After calculating pressure drop (head loss) i managed to have desired head of 378 ft at hydrants.
I had an idea, what about installing a single stage VTB with a head of 32ft to pump water from Atlantic Ocean to an elevated reservoir,then water flows by gravity to Industrial area in order to save costs?

 

[Artisi]

Shouldn't that be 378ft at the pump discharge?

And after the water gets to the industrial estate what happens next?

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.)

 

[optimomech]

No at pump pressure head is 400ft, i got 378ft after deductng head loss from head developed 400ft.
My mentor travels alot so he instructed me to conduct this project by researching, its quite challenging but very interesting.
Thank you very much Artisi,

 

[Artisi]

Pressure at the hydrants is supposed to be 200 ft as per your earlier post.
Think you need to sit down and write yourself an action plan of what is required and how you will solve each problem / situation.

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.)

 

[EnergyMix]

I think you might find that taking water from the ocean might be a bit challenging because of the salt in it. Also you would need to account for the tides. That might run your costs up a bit.

Want to know the do's and don'ts of Eng-Tips? Read FAQ731-376.
English not your native language? Looking for some help in getting your question across to others or understanding their answers? Go to forum1529.

 

[DRWeig]

Better screen for marine life (fishies) and seaweed too. I've had to spec valves for ocean water in some larger pipes, pinch valves were necessary.

Best to you,

Goober Dave

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[DRWeig]

I forgot to mention the reason for my post.

A screen fine enough to keep the junk out will have a large pressure drop. The screen will also clog up easily. I suppose there is a way to balance that, but I'm not the guy to ask.

Pumping seaweed up into a fire protection system could also stop up sprinkler heads, I would think.

I may be all wet here (pun intended). Someone will call me out if so.

Best to you,

Goober Dave

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[EnergyMix]

DRWeig, just being on a Great Lake, I can tell you that lakeweed can indeed clog up screens, enough to shutdown plants who take their water intakes from the lakes. And we won't talk about fish. I still have <not so fond> memories of a shad run that overcame the screens at a certain plant a long time ago. Overcame the backwash strainers as well. Did some damage to some heat exchangers (they pumped a LOT of ground up fish.)

I'm sure the oceans are gentler. Of course, they have hurricanes out there, that I don't have to worry about. Now that would be an interesting design twist. I'm sure our original poster is going to take that into account.

It's not that it can't be done. There's just additional equipment that needs to be added in that you don't have to consider if you just make a tie-in off the nearest city fire header.

By the way, since no one mentioned it: 200947761, you want to go see if you have the National Fire Protection Association (NFPA) codes available and start reading up on what's required.

Want to know the do's and don'ts of Eng-Tips? Read FAQ731-376.
English not your native language? Looking for some help in getting your question across to others or understanding their answers? Go to forum1529.

 

[handleman]

Umm, someone did mention codes. Not NFPA because, as the poster is obviously ESL, there's a high likelihood that a different code applies.

-handleman, CSWP (The new, easy test)