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 Posted: Jun 19, 2012 - 03:17 PM |
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Joined: Jan 25, 2002
Posts: 148
Location: Ruse , Bulgaria
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Hi ,
If someone knows a little bit about hydraulics - water pump... maybe you can help:
Suppose I buy a water pump with these specs:
Code:
- Brushless water pump consumption: 9V / 200mA
- Maximum water height: 70cm
- Maximum flow: 220L/H
- Maximum delivery lift: 150cm
Well, my question is:
If I will use a thinner tube (than original one), would I be able to get a delivery lift greater than 150cm ?
TIA. |
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Posted: Jun 19, 2012 - 03:20 PM |
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Joined: Nov 02, 2009
Posts: 3239
Location: Zelenograd, Russia
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| Yes. |
_________________
Warning: Grumpy Old Chuff. Reading this post may severely damage your mental health.
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Posted: Jun 19, 2012 - 03:26 PM |
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Joined: Jan 25, 2002
Posts: 148
Location: Ruse , Bulgaria
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| Thanks! |
Last edited by scuberula on Jun 24, 2012 - 06:42 PM; edited 1 time in total
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Posted: Jun 19, 2012 - 03:44 PM |
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Joined: Dec 11, 2007
Posts: 6982
Location: Cleveland, OH
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?
I thought the pressure, (back pressure on the pump in this case), is directly proprotional to the heigth of the water column, and not related to the diameter of the pipe.
JC |
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Posted: Jun 19, 2012 - 03:56 PM |
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Joined: Jan 25, 2002
Posts: 148
Location: Ruse , Bulgaria
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| So... it's not possible... I won't be able to get more than 150cm, right? |
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Posted: Jun 19, 2012 - 05:00 PM |
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Joined: Feb 19, 2001
Posts: 26115
Location: Wisconsin USA
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Posted: Jun 19, 2012 - 05:44 PM |
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Joined: Mar 27, 2002
Posts: 18757
Location: Lund, Sweden
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If a thinner tube would lift/press the water higher, then a thinner tube should be able to suck water from a deeper depth than a wider one. AFAIK the limit for sucking water is determined by the atmospheric pressure, so no matter the dimension of the tume you can not suck water from a depth of more than 10 meters (approximately). Since this can be seen as the atmospheric pressure at the level where the water is taken is the thing that presses the water up to the sucking pump then, and the dimension of the tube does not matter, then the dimension of the pipe should not matter for a pump that is pressing rather than sucking.
(Jeez, that was hard to formulate. Amazing how much easier it is to write about something, i.e. computers and stuff, that you deal with and read and write about daily, in a non-first language...) |
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Posted: Jun 19, 2012 - 06:45 PM |
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Joined: Nov 02, 2009
Posts: 3239
Location: Zelenograd, Russia
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| I meant it's possible to sprinkle the water higher when using a thinner tube. Of course not to deliver a water INSIDE the pipe. |
_________________
Warning: Grumpy Old Chuff. Reading this post may severely damage your mental health.
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Posted: Jun 19, 2012 - 09:44 PM |
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Joined: Sep 04, 2002
Posts: 21396
Location: Orlando Florida
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| How do they get water to the top of a building that's higher than 3 stories? Someone must have figured this out 100 years ago. |
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Imagecraft compiler user
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Posted: Jun 19, 2012 - 10:07 PM |
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Joined: Nov 11, 2003
Posts: 4040
Location: Chicago Illinois USA
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They pump it from below. You can't suck it that high, but you can push it.
Since his pump can only pump 150cm, that's the limit to its pressure and it doesn't matter what the tube looks like, it won't rise higher than 150cm. |
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Discursive design,
Torby
Some days, it's just not worth chewing through the restraints.
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Posted: Jun 19, 2012 - 11:20 PM |
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Joined: Mar 28, 2001
Posts: 20633
Location: Sydney, Australia (Gum trees, Koalas and Kangaroos, No Edelweiss)
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Quote:
higher than 3 stories? Someone must have figured this out 100 years ago.
...but that's another story...  |
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John Samperi
Ampertronics Pty. Ltd.
www.ampertronics.com.au
* Electronic Design * Custom Products * Contract Assembly
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Posted: Jun 20, 2012 - 01:04 AM |
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Joined: Jul 02, 2005
Posts: 6039
Location: Melbourne, Australia
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| John, are you taking over my (pedantic) job? |
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Ross McKenzie
ValuSoft
Melbourne Australia
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Posted: Jun 20, 2012 - 09:09 AM |
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Joined: Sep 20, 2003
Posts: 4115
Location: Surrey, England
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bobgardner wrote:
How do they get water to the top of a building that's higher than 3 stories? Someone must have figured this out 100 years ago.
You can also use mult-stage lift pumps - suck it up 10 metres into a tank, then suck it another 10 metres and so on. |
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Posted: Jun 21, 2012 - 05:08 AM |
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Joined: Dec 30, 2004
Posts: 9009
Location: Melbourne,Australia
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Posted: Jun 23, 2012 - 04:15 AM |
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Joined: Aug 05, 2005
Posts: 267
Location: Tacoma, WA
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Generally, all a smaller diameter pipe will give you is more energy losses in the pump discharge line. The pump injects a certain amount of energy into the the fluid discharged. The total energy in the line at any point is the sum of the velocity head plus the pressure head plus the gravity head. By making the line smaller you will increase the velocity, but the pressure will drop to offset that and the friction losses will be higher by a function of v^^2.
The energy equation is: E=v^^2/2g + P/fluid density + h (units are length).
E in = E out - E lost
In general, the answer to your question is no. Making the line smaller will not allow you to pump to a higher elevation, all other things being equal. However, it is a more complex question than it seems, and you really need to consult the pump curve to be sure.
Most pumps have a set of pump curves developed by the manuf that show the relationship between head, flow and power for a particular pump. These are usually available on the manuf web site.
Jim |
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Posted: Jun 23, 2012 - 10:42 AM |
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Joined: Mar 27, 2002
Posts: 18757
Location: Lund, Sweden
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Quote:
E in = E out - E lost
Is this a typo, or am I really lost?
If I solve that for E out I get
E out = E in + E lost
which looks like a self-pumping pipe to me, and would make for an Excellent perpetuum mobile. |
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Posted: Jun 23, 2012 - 03:51 PM |
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Joined: Aug 05, 2005
Posts: 267
Location: Tacoma, WA
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Ein - Elost = Eout.
The point here is that what you get out of the pump/discharge line system is always less than you put in because there are always losses in the system. Other things being equal, small lines increase losses.
No self pumping going on here. |
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Posted: Jun 23, 2012 - 05:25 PM |
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Joined: Mar 27, 2002
Posts: 18757
Location: Lund, Sweden
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Quote:
The point here is that what you get out of the pump/discharge line system is always less than you put in
Agreed, but the equation three posts above seems to say otherwise. I quote again:
Quote:
E in = E out - E lost
Can we agree that this is a typo, or is there actually something I am missing? |
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Posted: Jun 23, 2012 - 10:43 PM |
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Joined: Aug 05, 2005
Posts: 267
Location: Tacoma, WA
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| Its a typo. I should have been more careful when I wrote it down. My intent was to point out that engineers apply the law of energy conservation to analyze pump performance. |
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