Sciencey odd question just occured in my daily musings...

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100mm @ 4 bar straight run 25 miles = well enough for combi ( about 112 lpm) guestimated
 
dont worry they are electric, has anyone got a 25 mile extension lead?

in fact is the power the same, more or less on a long extension lead? what are the friction losses?
 
I get the jist
The power output (work done ) will be what it is determined by the power input (work Supplied)
 
I'm not still convinced by (mainly because I don't understand half of them) the arguments given so far. So I'll modify the question..

Ingoring pumps or the nature of the force that has created the pressure, ignoring friction or other factors. Imagine there is a hyperthetical pipe potentially as long as the universe itself if need be. At one end is say 1.5 bar pressure. At the other end a tap. This pipe has no friction, it has not fluctuations of temperature. It's dead-level.

The question to which I want a yes or no answer is.....Could this pipe be long enough so the weight of the water itself to be moved by the standing pressure be so great that the pressure couldn't shift it? Yes or no people, time to vote...

*countdown music*
 
NO there is no gravity in space therefore the water would be weightless
 
so if you opened the hypothetical tap you would just release the pressure and that would be it
 
If there is no friction then there are no friction losses so the pressure remains constant
 
tamz said:
If there is no friction then there are no friction losses so the pressure remains constant
Click to expand...

But he said no pump so how do you maintain said pressure in a level pipe how ever long?
 
Never noticed that bit:shame:

So, if i've got this right, we have a level pipe of infinite length with no applied pressure but as it is on earth, it is subjected to gravity.
Cut the end off the pipe and it will empty...............eventually.
 
if your talking about a pipe in outer space their wouldnt be any pressure and if you opened each end water wouldnt flow anywhere, it would stay still, untill someone moved it, using a force of pressure or gravity moved the water down..
 
Ah, but we are now back on earth (post 59) so subject to the usual forces :lol:
 
water run level for a long distance, say 1000 miles, i dont think would work, due to the moons pull on water, just look at the sea, it goes in and out, but i think it would work if the water was raised up from the ground, as that would increase its pressure..its pressure would never come down over the 1000miles, but its flow rate would due to friction so you'd have to fit the currect sized pipe to cater for its run

if size didnt matter, the water board would be using 15mm pipe under our roads to feed everyones home.. i dont know the math in sizing water mains though
 
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well if run totally level without any real pressure, bar its own pressure due to its own weight on the earths gravitational pull and say we had no moon, if you opened each end water would flow out slowly, but factoring it the moons pull on water, depending on where the moon was water would naturally want to follow the moons path, would it not ?

dont really understand the question, who'd want to fit a pipe without increasing its pressure
 
I suppose as long as the money was right , wgaf. Just keep laying pipe. No pressure as it is an infinate job!

I'm out:sleep1:
 
mickie said:
if your talking about a pipe in outer space their wouldnt be any pressure and if you opened each end water wouldnt flow anywhere, it would stay still, untill someone moved it, using a force of pressure or gravity moved the water down..
Click to expand...

there is gravity on the moon, its just reduced 1.6n/s/s instead of 9.8n/s/s. So i pipe on the moon 25 miles long would take 1/6 of the time to empty. However, if it were pumped and pumped upwaards the restriction due to gravity would be less, its all pros and cons lads
 
Well I'm still a bit confused but I think the answer is too many other factors would get in the way of the experiment.

I suppose what I want to imagine is say you are on this magical world for this experiment - you have this level stretch of 1000 miles of pipe, which is not effected by friction, is neither subject to the effects of gravity nor the effects of no gravity, where the only thing being tested, somehow - magically - is whether the mass of this water itself can hold back pressure when applied.

So this pipe would be full of water but not pressurised. Just at the pressure it normally would be at. At the far end is a tap which will be opened shortly. Then, 1000 miles back the other away is a valve which is closed. On the other side of the valve is more pipe, containing water which is pressurised to 1.5 bar. If you open the valve the pressurised water comes into contact with the non-pressurised water, sitting there for it's 1000 mile stretch - if you then open the tap 1000 miles away does water come out or not?
 
And if this has now been answered already and I'm just too thick to get it and everyone else does I apologise and will stop bothering everyone :43:
 
not answerd yet dont forget if a pipe is a 1000 miles long layin on a planet, the natural curvature of the planet will allow air in when you open the pipe allowing the water to pour out
 
WaterTight said:
Well I'm still a bit confused but I think the answer is too many other factors would get in the way of the experiment.

I suppose what I want to imagine is say you are on this magical world for this experiment - you have this level stretch of 1000 miles of pipe, which is not effected by friction, is neither subject to the effects of gravity nor the effects of no gravity, where the only thing being tested, somehow - magically - is whether the mass of this water itself can hold back pressure when applied.

So this pipe would be full of water but not pressurised. Just at the pressure it normally would be at. At the far end is a tap which will be opened shortly. Then, 1000 miles back the other away is a valve which is closed. On the other side of the valve is more pipe, containing water which is pressurised to 1.5 bar. If you open the valve the pressurised water comes into contact with the non-pressurised water, sitting there for it's 1000 mile stretch - if you then open the tap 1000 miles away does water come out or not?
Click to expand...

no, the weight of water would be too much for 1.5 bar to overcome it
 
unguided1 said:
not answerd yet dont forget if a pipe is a 1000 miles long layin on a planet, the natural curvature of the planet will allow air in when you open the pipe allowing the water to pour out
Click to expand...

arrrhhhhh

ok, lets also pretend the earth is flat
 
fuzzy said:
no, the weight of water would be too much for 1.5 bar to overcome it
Click to expand...


Soooo.....what we want to know is, how long would a piece of 15mm copper full of water need to be when subjected to 1.5 bar before water couldn't come out of the other end but ONLY because the weight of the water in said pipe would be too great for it to be pushed out by available pressure?

I've done the calculations and its 643.274653 miles. No need to check, 100% accurate, absolutely.
 
I'm sorry guys but water would boil in space, thats what happens to you in space the water inside yer body boils !

ohh and did you know that at the deepest part of the ocean the mariana trench(6.85miles) the pressure is over 8 tons per square inch ?? lol
 
Only just read this gem of a thread - physics, maths and astonomy - my all time favourite subjects, appart from a few not taught in my catholic school!

In deep space the temperature is just 3 degrees warmer than absolute 0 so approx -270 C
So the water will definitely freeze.
Not sure what happens to copper or plastic at these temperatures.

As said earlier if there were no forces such as gravity or friction then ANY body set in motion will continue to move in a staight line at a constant speed, as in a vacuum or deep space.
In side the theoretical frictionless pipe the water release at mains pressure will continue to move at the same speed BUT i think you question is that this water then meets an obstacle which is the still water sitting in the pipe.
So you need enough pressure to move the still water. Sorry if i am repeating what was said..

I'm not sure the moon will have any effect on the water in the miles of pipe. Because I think the moon - tide thing is to do with a big body of water like a giant swimming pool. Along this theoretical pipe there is always a small amount of water in any one place.
 
While you were writing I was checking my facts!
of course I forgot that water boilers at lower temperature when pressure drops.
I don't know what the pressure is in deep space?

But I was thinking of comets and rocks like pluto being largely frozen ice. But of course they have mass and pressumably higher pressure than deep space. Makes you think...
 
[DLMURL="http://scienceblogs.com/startswithabang/2009/06/water_in_space_what_happens.php"]Water in Space: What Happens? : Starts With A Bang[/DLMURL]

interesting page
 
Last edited by a moderator:
sorry correction, it boils faster than freezing so in effect it is freezing but turning into a gas at the same time lol mad
 
fuzzy said:
do you have 25 mile of copper on the van?

diamondgas wants to do it in speedfit, but i think thats cheating, in fact ive decided hes a big wuss now and i o longer consider him a real plumber, psss, dont tell him

how about doing it in iron? ive got some hand dies
Click to expand...

I have'n got a finger big enough for iron fuzzy and i am a wuss .... :) Part time plumber full time gas engineer :rofl: Haven't got a clue when in comes to anything waste related and have never fancied messing with toilets, baths and the like... leave that to the proffesionals lol ...
 
WaterTight said:
Soooo.....what we want to know is, how long would a piece of 15mm copper full of water need to be when subjected to 1.5 bar before water couldn't come out of the other end but ONLY because the weight of the water in said pipe would be too great for it to be pushed out by available pressure?

I've done the calculations and its 643.274653 miles. No need to check, 100% accurate, absolutely.
Click to expand...

so your saying we are good for the first 642 miles?
 
diamondgas said:
I have'n got a finger big enough for iron fuzzy and i am a wuss .... :) Part time plumber full time gas engineer :rofl: Haven't got a clue when in comes to anything waste related and have never fancied messing with toilets, baths and the like... leave that to the proffesionals lol ...
Click to expand...

its all very clear now, so how far would gas travel if subjected to a force of 1.5bar in a 15mm copper tube?
 
fuzzy said:
its all very clear now, so how far would gas travel if subjected to a force of 1.5bar in a 15mm copper tube?
Click to expand...

Up hill, down or on the level? I'd be gettn' the meter gov checked if I was getting that sort of presure ... imagine the cooker flame!!! lol
 
Lot's of smoke and mirrors on this one guys. I wonder when they stopped teaching the Hydraulic Gradient phenomenon to plumbers?? ; anyhow our plumbing teacher used to have a rig with 1/4" dia horizontal pipe about 2 metres long with a tap on one end. There were vertical branches (open ended) from the pipe at about 200mm intervals in glass pipe about 400mm high. and the end branch away from the tap end had a bit of a reservoir which was filled with coloured water, firstly with the tap closed so that the whole rig was filled and you could see coloured water at equal heights in each vertical branch. When the tap was opened and the water flowed the level in each branch dropped but not equally so that you could actually run a line through from the resevoir to the tap. This was to demonstrate the difference between Static Pressure and Hydraulic pressure .. that is when water flows through a pipe it loses pressure due to friction against the pipe wall.So in this way you would be able to easily find out if the original question is true by setting up a bigger scale rig (but still with 1/4") and experiment with the reservoir height and length of pipe till nothing comes out. Good luck
 
Last edited by a moderator:
that sounds interesting any chance of a skethc or link to it happening on you tube or something?
 
For me, personally, it turns out I had a big enough brain to think up the question but far too small a brain to understand half the answers. But since ignorance is evidently bliss I'm not complaining.
 
I couldn’t let the challenge of this question leave my head
I think the friction is irrelevant and I think the amount of water in the pipe needs to be big enough to be exerting and equal and opposite force to the mains pressure
I may have the answer found in a plumbing book as to when the 3 bar of mains pressure runs out, I could be very wrong.
Please check my maths I may have made massive mistakes.

Townsend Plumbing 1 second edition 1969

Pages 51-3 chapter about water.

If we assume water pressure of 3 bar = 30 m head
And 15mm pipework

Intensity of pressure = head x 9.8 kilo Newton kN/m2
= 294 kN/m2
Total pressure = intensity of pressure x area
Total pressure = 294 kN/m2 x (3.142 x 7.52) m2= 51,961 kN

1 tonne of force = 1000 kg f = 9800 newtons = 1m3 of water

Therefore:
51,961 / 9.8 = 5,302 tonnes = 53,020m3 or 53 million litres of water

I think this means that 3 bar mains water pressure is enough to move 5,302 tonnes of water through a 15mm pipe

A litre is 1cm3 of water and if this pipe hold 0.15 litres per metre then 150 litre per km

At this point I have lost interest and Big Bang has come on TV … come on I’m nearly there.

353,467 kilometres of pipe filled with water.
By the way, circumference of the earth is a little over 40,000. so to all practical terestrial purposes the water will never stop coming.
 
Mrs Tara Plumbi said:
I couldn’t let the challenge of this question leave my head
I think the friction is irrelevant and I think the amount of water in the pipe needs to be big enough to be exerting and equal and opposite force to the mains pressure
I may have the answer found in a plumbing book as to when the 3 bar of mains pressure runs out, I could be very wrong.
Please check my maths I may have made massive mistakes.

Townsend Plumbing 1 second edition 1969

Pages 51-3 chapter about water.

If we assume water pressure of 3 bar = 30 m head
And 15mm pipework

Intensity of pressure = head x 9.8 kilo Newton kN/m2
= 294 kN/m2
Total pressure = intensity of pressure x area
Total pressure = 294 kN/m2 x (3.142 x 7.52) m2= 51,961 kN

1 tonne of force = 1000 kg f = 9800 newtons = 1m3 of water

Therefore:
51,961 / 9.8 = 5,302 tonnes = 53,020m3 or 53 million litres of water

I think this means that 3 bar mains water pressure is enough to move 5,302 tonnes of water through a 15mm pipe

A litre is 1cm3 of water and if this pipe hold 0.15 litres per metre then 150 litre per km

At this point I have lost interest and Big Bang has come on TV … come on I’m nearly there.

353,467 kilometres of pipe filled with water.
By the way, circumference of the earth is a little over 40,000. so to all practical terestrial purposes the water will never stop coming.
Click to expand...

My brain just burst :willy_nilly:
 
Mrs Tara Plumbi said:
I couldn’t let the challenge of this question leave my head
I think the friction is irrelevant and I think the amount of water in the pipe needs to be big enough to be exerting and equal and opposite force to the mains pressure
I may have the answer found in a plumbing book as to when the 3 bar of mains pressure runs out, I could be very wrong.
Please check my maths I may have made massive mistakes.

Townsend Plumbing 1 second edition 1969

Pages 51-3 chapter about water.

If we assume water pressure of 3 bar = 30 m head
And 15mm pipework

Intensity of pressure = head x 9.8 kilo Newton kN/m2
= 294 kN/m2
Total pressure = intensity of pressure x area
Total pressure = 294 kN/m2 x (3.142 x 7.52) m2= 51,961 kN

1 tonne of force = 1000 kg f = 9800 newtons = 1m3 of water

Therefore:
51,961 / 9.8 = 5,302 tonnes = 53,020m3 or 53 million litres of water

I think this means that 3 bar mains water pressure is enough to move 5,302 tonnes of water through a 15mm pipe

A litre is 1cm3 of water and if this pipe hold 0.15 litres per metre then 150 litre per km

At this point I have lost interest and Big Bang has come on TV … come on I’m nearly there.

353,467 kilometres of pipe filled with water.
By the way, circumference of the earth is a little over 40,000. so to all practical terestrial purposes the water will never stop coming.
Click to expand...

Yeah wot evar but is it enough fer the loveslave ter fill the kettle?????
 
Mrs Tara Plumbi said:
I couldn’t let the challenge of this question leave my head
I think the friction is irrelevant and I think the amount of water in the pipe needs to be big enough to be exerting and equal and opposite force to the mains pressure
I may have the answer found in a plumbing book as to when the 3 bar of mains pressure runs out, I could be very wrong.
Please check my maths I may have made massive mistakes.

Townsend Plumbing 1 second edition 1969

Pages 51-3 chapter about water.

If we assume water pressure of 3 bar = 30 m head
And 15mm pipework

Intensity of pressure = head x 9.8 kilo Newton kN/m2
= 294 kN/m2
Total pressure = intensity of pressure x area
Total pressure = 294 kN/m2 x (3.142 x 7.52) m2= 51,961 kN

1 tonne of force = 1000 kg f = 9800 newtons = 1m3 of water

Therefore:
51,961 / 9.8 = 5,302 tonnes = 53,020m3 or 53 million litres of water

I think this means that 3 bar mains water pressure is enough to move 5,302 tonnes of water through a 15mm pipe

A litre is 1cm3 of water and if this pipe hold 0.15 litres per metre then 150 litre per km

At this point I have lost interest and Big Bang has come on TV … come on I’m nearly there.

353,467 kilometres of pipe filled with water.
By the way, circumference of the earth is a little over 40,000. so to all practical terestrial purposes the water will never stop coming.
Click to expand...

.....Guh?
 
see if i got this, if you have 353,467km of 15mm tube, 3 bar is sufficient?
 
fuzzy said:
see if i got this, if you have 353,467km of 15mm tube, 3 bar is sufficient?
Click to expand...
Fuzzy - exactly the opposit
3 bar will not move this amount of water!

As I said:
1. i may have made a mistake with the maths as this seems a really big number, the the principles were right but my sums wrong OR
2. these formulas might be completely the wrong way of working out the answer

And - as when the computer said the answer is 42 then they set off to fing out the question.
the question i think i have tried to answer is if pipe was laid completely flat, no bends, how much standing water would be in the pipe before you could turn on 3 bars of mains pressure but not move anything?

Me thinks this should be addressed to some maths forum or we should just stick with the experiment as discussed.
What are the chances of winning lottery funding to fund the experiement which will prove my answer correct or incorrect?
 
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