Previous in Forum: Electric Motor for Rotating Cylinder   Next in Forum: AISI 410 Vs 420
Close
Close
Close
14 comments
Rate Comments: Nested
Member

Join Date: Feb 2014
Posts: 7

Calculation of Pressure Versus High Water Column

02/26/2014 9:40 PM

Dear all, I wants to know any formula / thumb rule to calculate / confirm the pump head. One pump is running with presure of suction and discharge 1.2 / 3.4kg/cm². how to find the suction pressure of pump with system standing pressure (water column) is 2.0kg/cm² and pump head 25mtr. what is basic formula for calculate the pressure of vertical water column and pressure versus vertical water column.

Register to Reply
Pathfinder Tags: water column versus pressure
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#1

Re: calcultion of pressure versus high water column

02/26/2014 10:22 PM
Register to Reply
Guru

Join Date: Mar 2012
Location: Out of your mind! Not in sight!
Posts: 4424
Good Answers: 108
#2

Re: calculation of pressure versus high water column

02/26/2014 11:04 PM

It just adds up doesn't it?

__________________
Common Sense Dictates
Register to Reply
Associate

Join Date: Apr 2012
Location: Lollipop Land
Posts: 34
Good Answers: 2
#3

Re: calcultion of pressure versus high water column

02/26/2014 11:08 PM

> it just adds up, doesn't it?

sum times

__________________
Toto, I've a feeling we're not in Kansas anymore
Register to Reply
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 21017
Good Answers: 795
#4

Re: calcultion of pressure versus high water column

02/26/2014 11:47 PM

1 psi ≡ 2.31 feet

__________________
In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32175
Good Answers: 839
#5

Re: calcultion of pressure versus high water column

02/27/2014 5:49 AM

That stuff is O-level Physics - variaton of pressure with depth, that sort of thing.

__________________
"Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply
Guru
United Kingdom - Member - New Member

Join Date: Aug 2010
Location: Resting under the Major Oak
Posts: 4347
Good Answers: 181
#14
In reply to #5

Re: calcultion of pressure versus high water column

03/01/2014 5:45 AM

It's raining here at the moment. Who can I blame it on?

__________________
The reports of my death are greatly exaggerated.
Register to Reply Off Topic (Score 5)
Guru

Join Date: Jul 2005
Location: Stoke-on-Trent, UK
Posts: 4496
Good Answers: 137
#6

Re: calcultion of pressure versus high water column

02/27/2014 7:34 AM

Not clear what you're asking. As #5, calculating (static) pressure from water column is elementary physics, but that doesn't give you actual pressures at pump suction and discharge, you need to allow for pipe friction.

Is there just one set-up here, with system standing pressure (water column) 2.0kg/cm² and pressure of suction 1.2kg/cm² (the difference being friction loss) or are you trying to work out change in performance if suction pressure changes?

What do you mean by pump head, is this generated head?

__________________
Give masochists a fair crack of the whip
Register to Reply
Member

Join Date: Feb 2014
Posts: 7
#7
In reply to #6

Re: calcultion of pressure versus high water column

02/27/2014 11:08 AM
  • I wants to know any formula / thumb rule to calculate the pump head. what will the head of pump, if it is running with 1.2 kg/cm² suction and 3.4 kg/cm² discharge pressure.
  • what will the pressure at bottom of 10 mtr high water column.
  • how to find / guess / the suction pressure of pump before start. If any pump of 25 mtr head is equiped in inclosed circuit and circuit is having 2.0kg/cm² standing pressure.
Register to Reply
Guru

Join Date: Jul 2005
Location: Stoke-on-Trent, UK
Posts: 4496
Good Answers: 137
#8
In reply to #7

Re: calcultion of pressure versus high water column

02/27/2014 12:07 PM
  • I wants to know any formula / thumb rule to calculate the pump head. what will the head of pump, if it is running with 1.2 kg/cm² suction and 3.4 kg/cm² discharge pressure.

That's just a repeat of your original post. Need answers to my questions to try to help

  • what will the pressure at bottom of 10 mtr high water column.

Elementary physics, but if you can't do that, it's 1 barg near enough, if everything's static and open to the atmosphere

  • how to find / guess / the suction pressure of pump before start. If any pump of 25 mtr head is equiped in inclosed circuit and circuit is having 2.0kg/cm² standing pressure.

First time you've mentioned closed circuit, is it a heating system? For a closed circuit you need either a header tank or an expansion vessel, to cater for water expansion (even if it's not a heating system). The connection to the header tank or an expansion vessel should be close to the pump suction, so that is the point of minimum pressure. The header tank should be high enough to provide pump NPSHR plus a margin (or expansion vessel pre-charge to provide it). The pump does not see any static differential head, only friction. Other than that you need to give more detail.

__________________
Give masochists a fair crack of the whip
Register to Reply
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#9
In reply to #7

Re: calcultion of pressure versus high water column

02/27/2014 5:49 PM

LynDoor™Industries Guess-O-Matic head calculator can solve those pesky head calculation problems.

It's management approved for budgeting and proposal calculations.

For an additional fee, it can be calibrated and certified.

And various multipliers can be assigned to each ring for added flexibility, depending on customer astuteness level. They are BS, MS and PhD.

Register to Reply
Participant

Join Date: Nov 2009
Posts: 2
#10
In reply to #9

Re: calcultion of pressure versus high water column

02/27/2014 11:20 PM

Hi,

25 m head = 2.5 bar approximately.

Register to Reply Score 1 for Good Answer
Power-User

Join Date: Jul 2008
Location: Adelaide, Australia
Posts: 403
Good Answers: 14
#11

Re: Calculation of Pressure Versus High Water Column

02/28/2014 2:05 AM

Hi dspataw

http://joshmadison.com/convert-for-windows/

This is a free program, but I note under "Pressure" it doesn't have a direct conversion from water head in feet to PSI or m to Kpa. You can program this in yourself. 1m head = 10.19Kpa. Tony

__________________
The nice thing about Standards is there are so many to choose from.
Register to Reply
Guru

Join Date: Jul 2005
Location: Stoke-on-Trent, UK
Posts: 4496
Good Answers: 137
#12
In reply to #11

Re: Calculation of Pressure Versus High Water Column

02/28/2014 7:06 AM

It doesn't have a direct conversion from water head in feet to PSI or m to kPa because they don't have the same units. Pressure = h*ρ*g (in consistent units, extra factor otherwise) so density ρ is needed, and the calculator doesn't have the facility. Also g, but that's usually taken as constant.

But I'm not sure the OP is only asking for head to pressure conversion, he seems to want somebody to analyse his system.

__________________
Give masochists a fair crack of the whip
Register to Reply
Power-User

Join Date: Jul 2008
Location: Adelaide, Australia
Posts: 403
Good Answers: 14
#13
In reply to #12

Re: Calculation of Pressure Versus High Water Column

02/28/2014 8:57 AM

Yes you are correct, I've spent too much time with water to realise there are are densities. Anyhow the the calulators good isn't it and I hope g continues to stay constant (stupid bloody newtons). Tony

__________________
The nice thing about Standards is there are so many to choose from.
Register to Reply
Register to Reply 14 comments

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

Codemaster (3); dspatawat (1); IdeaSmith (1); lyn (2); MagicWand (1); PWSlack (1); Tonymech (2); TonyS (1); Tornado (1); ur_n73b (1)

Previous in Forum: Electric Motor for Rotating Cylinder   Next in Forum: AISI 410 Vs 420

Advertisement