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Anonymous Poster #1

Selection Of Pump

12/08/2014 2:08 AM

I want to pump 2500000 Kg/hr water from an open tank which is under atmospheric pressure. Temperature of water inside tank is around 34.9 Degree Celsius. Differential head reqd. is 35 meter. Mech. efficiency of pump to be 70% and motor efficiency to be 90%. Density of water @ 34.9 degree is not avilable. I want to select pump before procurement. How to find pump shaft power and motor power.

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#1

Re: Selection of pump

12/08/2014 2:26 AM

Sounds like homework.

Procurement would not even bother looking at temperatures!

You might want to find the power that is needed to get the water where you need it and apply your efficiencies and voila there will be the power.

With a bit of effort you can do this!

Watch out, its a trick question. The density of water at the given temperature is the most important missing parameter!

Have fun!

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#2

Re: Selection of pump

12/08/2014 3:01 AM

"Temperature of water inside tank is around 34.9 Degree" - get real! How accurate do you think the efficiency figures are? ±5%? Maybe, if you're very lucky.

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#3

Re: Selection of pump

12/08/2014 7:20 AM

Read something about total dynamic head.

You may approximately use 1000kg/m3 density. if you want the exact find a steam tables on the net, find vf @ 34.9C Pressure at 14.7psi density is just the inverse of vf.

eff. =WHP/BHP

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#4

Re: Selection of pump

12/08/2014 7:55 AM

Speak to your chosen pump supplier(s) and ask them. Be prepared to also provide information on inlet and outlet pipe sizing, layout and tank connection as well as any other flow restrictions. Please note that 34.9 C is close enough to 35 C for any practical engineering calculations that you should be able to find or calculate the density from steam tables (they often have this sort of information for feedwater). Lastly, unless this is homework pumping on the order of 700 litres of water per second seems to be a fairly important undertaking, enough to warrant more than the opinion of posters on an anonymous forum.

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#17
In reply to #4

Re: Selection of pump

12/09/2014 8:01 AM

issues on anti-trust is critical

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#5

Re: Selection Of Pump

12/08/2014 8:39 AM

Homework alert!

Your first assignment is to convert 2500000 Kg/hr into volume.

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Anonymous Poster #1
#36
In reply to #5

Re: Selection Of Pump

12/12/2014 5:54 AM

Thanks lyn, you are correct.I have changed mass flow rate to volumetric flow.Then I used rho*g*h formula to find pressure in bar.I will update, if I complete this issue properly.

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Anonymous Poster #1
#37
In reply to #36

Re: Selection Of Pump

12/12/2014 6:05 AM

One more step forward

Pump shaft power req. = Theoritical power req. devided by pump efficiency

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Anonymous Poster #1
#38
In reply to #37

Re: Selection Of Pump

12/12/2014 6:12 AM

Oh I am tired after this complex calculation. Somebody calling me from weld shop.Shop fellows might have executed seam overhead weld again on 30mm thick ASS pipe.Give me a break.

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#6

Re: Selection Of Pump

12/08/2014 8:51 AM

Because I don't believe you have confidence in yourself to read a pump curve and since you have to buy your pump, contact a pump supplier to ensure correct sizing.

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#7

Re: Selection Of Pump

12/08/2014 8:51 AM

It could be either you or your instructor's fault.

Blame him for not teaching you the very best way that you would learn and/or yourself for not listening or not learning the basics ever since.

Change your mind, you could either be on track or off track on whatever you pursue.

The easiest way might not be beneficial for your future.

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Anonymous Poster #1
#13
In reply to #7

Re: Selection Of Pump

12/08/2014 8:25 PM

Can I borrow your brain for few days as I am seriously looking for a Nobel prize.

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#14
In reply to #13

Re: Selection Of Pump

12/08/2014 8:28 PM

Contact the Wizard for a brain.

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Anonymous Poster #1
#15
In reply to #14

Re: Selection Of Pump

12/08/2014 9:06 PM

Thanks for the trillion dollar advice current nobel laureate.

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#18
In reply to #13

Re: Selection Of Pump

12/09/2014 8:05 AM

Wow, i am not sure i have one its dilated suspended in space of nothingness.

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Anonymous Poster #1
#8

Re: Selection Of Pump

12/08/2014 9:11 AM

Thanks all for the replies. There are some serious errors found in the given values in my OQ. If time permits, I will let you know the correct values.

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#9
In reply to #8

Re: Selection Of Pump

12/08/2014 9:23 AM

Don't bust a gut.

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#10
In reply to #8

Re: Selection Of Pump

12/08/2014 12:26 PM

Contact a pump supplier, directly.

Coming here just wastes our time and yours.

Your pump supplier (if they are any good) will insist on having the needed information and doing the calculations themselves.

That way, you'll get the pump you need, not the one you THINK you need.

If this is homework, we don't do homework here!

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Anonymous Poster #2
#11

Re: Selection Of Pump

12/08/2014 12:50 PM
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Anonymous Poster #1
#16
In reply to #11

Re: Selection Of Pump

12/08/2014 9:11 PM

CR4 ADMIN: Deleted Post

Vulgar/Rude/Improper Behavior: This post was deleted because it did not adhere to the behavioral policies of the site. Please review Section 14 of the CR4 Site FAQ and the CR4 Rules of Conduct.

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Anonymous Poster #1
#19
In reply to #16

Re: Selection Of Pump

12/09/2014 9:13 AM

Anonymous#2 might have produced physically fit certificate to CR4 moderator!

Other possibilities,which need more analysis

1. He/She is an illiterate to understand the OQ.

2. He/she entered in this forum to purchase toys and vegetables.

3. He/she was under drug or liquor.

4. Activity of an illiterate kid

5. Coded message from a potential terrorisht?

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Anonymous Poster #2
#20
In reply to #19

Re: Selection Of Pump

12/09/2014 9:21 AM

When you don't know enough to make an informed choice, this venerable selection technique is just as good as another.

[Sheesh lighten up a little. It will do you some good.]

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Anonymous Poster #1
#21
In reply to #20

Re: Selection Of Pump

12/09/2014 9:32 AM

It is none of your business to comment on what I have to do by showing a nonsense link. You are permitted to comment based on my OQ. If it is suitable I will select it after my analysis.If it is not suitable I will throw it in the trash bin.If you have nothing relevant to share, better sit back and watch the game.

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Anonymous Poster #2
#22
In reply to #21

Re: Selection Of Pump

12/09/2014 11:58 AM

Excuse me. You have no authority here. Your poor etiquette here has already caused administration to act. If you insist on not even a polite joke in your presence then you have to pay people.

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Anonymous Poster #1
#25
In reply to #22

Re: Selection Of Pump

12/09/2014 12:39 PM

Oh really, I was not aware that this forum is only for jokes and jokers.Thanks for the enlightenment.administration? who are they?

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#26
In reply to #25

Re: Selection Of Pump

12/09/2014 2:17 PM

You provide an object lesson for potential posters.

1. Don't post stupid questions.

2. Don't insult the people you ask for help.

3. Rudeness never wins friends, but may influence your enemies.

4. Never argue with a fool. On lookers may not be able to tell the difference.

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#27
In reply to #26

Re: Selection Of Pump

12/10/2014 7:06 AM

Good Suggestions.

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Anonymous Poster #1
#28
In reply to #27

Re: Selection Of Pump

12/10/2014 9:50 AM

yES sIR

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Anonymous Poster #3
#31
In reply to #25

Re: Selection Of Pump

12/11/2014 4:25 AM

girl alert probably...i love girls..who else does here?

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Anonymous Poster #1
#32
In reply to #31

Re: Selection Of Pump

12/11/2014 4:55 AM

CR4 ADMIN: Deleted Post

Vulgar/Rude/Improper Behavior: This post was deleted because it did not adhere to the behavioral policies of the site. Please review Section 14 of the CR4 Site FAQ and the CR4 Rules of Conduct.

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Anonymous Poster #3
#33
In reply to #32

Re: Selection Of Pump

12/11/2014 5:23 AM

Nah, just kidding around. It's a humor seeing Anon#1 and 2 argue.

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Anonymous Poster #1
#34
In reply to #33

Re: Selection Of Pump

12/11/2014 6:07 AM

Oh, I thought that you are searching for girls in this forum.Everyday plenty of people are coming here for various requirements.So, it is very difficult to asses their actual requirement without proper communication.Actually,I was trying to help you.

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Anonymous Poster #3
#35
In reply to #34

Re: Selection Of Pump

12/11/2014 9:45 AM

nice one, makes me smile though, with a thought "would i give it a try?lol

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#23
In reply to #11

Re: Selection Of Pump

12/09/2014 12:09 PM

I suggest a dart board.

With child proof darts of course.

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#24
In reply to #23

Re: Selection Of Pump

12/09/2014 12:38 PM

If your having a tantrum they should bounce off of the dart board instead of sticking. This would be good choice for random selections.

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#12

Re: Selection Of Pump

12/08/2014 2:08 PM

The shaft power is the flow rate multiplied by the rise in pressure divided by the pump efficiency.

The motor power is the shaft power divided by the motor efficiency.

The only tools you need are your pocket calculator and a telephone to talk to potential vendors.

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#29

Re: Selection Of Pump

12/10/2014 12:59 PM

Assuming I did my algebra properly, you hope to move more water than the combined average water flow of the Dettifoss and the Jockfallet waterfalls with one pump and to pump this up by 35 meters. I want to know how big is this mythical open tank?

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#30
In reply to #29

Re: Selection Of Pump

12/10/2014 1:08 PM

Well, are you familiar with Lake Superior?

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#39

Re: Selection Of Pump

03/28/2020 4:06 AM

Dear Friend, The calculation is as follows and your

GIVEN DATA:

FLOW : 25,00,000 Kgs./Hr. = 694.44 Kgs,/Sec. Head : 35 Metres Efficiency : Pump -70% Motor - 90% Water Temp.: 34.9 Deg.C Hence from Tables Density = 994.0357 Kgs/M^3 (Or) 0.994039

CALCULATIONS:

Assumed Data – Suction Velocity – 1.0 M/sec. Delivery Velocity – 2.0 M/Sec.

Power Required is (W X H) / 75 x (Pump Eff.) x (Motor Eff.) Since 75 Kg. M is one H.P. absolute shaft power.

Hence

(694.444) x (35)/ (75) (0,7) x (0.9) = 661,37 H.P = 496.028 KW

Rounded to 500 KWe

3. PIPE Size

a) Suction Pipe

Flow in (M^3/Sec) =

(Weight in Kg./Sec.)/1000)) /(Density) = Area x Velocity

(694.44 Kg.Sec)/(0.994) = {0.698635} M ^3/Sec. = Area x 1,0 M/sec

Therefore Area = 0.6986 sq. m = (( 22/7)/4) x D^2

Therefore Suction Pipe Dia., = 0.6369 Metre = 636.9 MM Rounded to 650 MM

b) Delivery Pipe: Velocity = 2.0 Metres.

Dia. Of Delivery pipe calculated similarly as 478.8 MM rounded to 480 MM

DHAYANANDHAN.S

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