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

[fuzzy]

thanks tara, good effort

i love the maths, when i get chance ill work through the sums and tell you how far 3bar can push

 

[TGor]

This is a sketch of the hydraulic gradient rig as I remember it! The difference in head seen at each vertical is caused by the friction loss due to flow in the pipe. This rig demonstrates it in a really practical way .. of course there are many formulae and methods to calculate theoretical friction losses in pipework systems but seeing is believing!!

 

[TGor]

Mrs Tara Plumbing .. friction is not irrelavent ot the question as if there were no friction there would be pressure loss and that is the key to this question.

pressure losses due to friction between th water flowing and the pipe wall are a function of the velocity (and a few other things like pipe roughness etc.) the higher the pressure the higher the velocity the higher the pressure loss .. therefore as the water runs through this imaginary endless pipe the pressure will gradually reduce proportionally to the loss due to friction and thus the velocity will reduce and so the loss will reduce and so on and so and until there will be such little velocity that there is hardly any loss and the pipe will not run full and it will trickle out but never stop fully as the flow and friction will reach equilibrium.

There is a true story about an engineer in Western Australia that ran a 30" water pipe from Perth to Kalgoorlie to the western goldfields a total length of 330 miles and the water took only 2 day to get there. The engineer commited suicide towards the end of the project because everyone was saying it wouldn't work!!

Interesting stuff this thanks all!

 

[dontknowitall]

Hmmm ...

View attachment 3465

 

[Kimou]

Gravity can't be dismissed. It's relative to pressure. It's like doing an experiment on the shadow of a 5p coin but removing the coin.

The moon affects the tides by proxy. It affects airs pressures which in turn compress and releases pressures on the oceans.

This pipe would have to be lined in exact ratio to the sea as no land mass will keep constant levels for the duration of such lengths.But by gradual reduction due to friction it will inevitably reduce to a trickle. This trick will eventually still manage to pass out the other end due to water's property of adhesion so cutting an inch off the terminal will not result in a sudden gush of pressure due to that pressure being exhausted miles ago.

 

[kay-jay]

working on the principle that every action has an equal and opposite re-action is it possible that at one end of this ridiculously long pipe if i insert my finger, it will appear out of the other end of the pipe and poke watertight in the eye for opening this can of worms?????

 

[PlumbBobBob]

A litre is 1cm3 of water.[/QUOTE

i think it is actually 10cm3 not 1cm3

 

[kay-jay]

yep thats right steve, well spotted.

1x1x1 does not equal 1000, 10x10x10 on the other hand...............

 

[Kimou]

A litre is 1cm3 of water.[/QUOTE

i think it is actually 10cm3 not 1cm3

I thought it was just a typo. But it's something every plumber should know about; relative density. Again, this is at atmospheric pressures. If you move the goal posts all sorts can happen. It's how the Triple State of Water exists at the same time. Solid-liquid-gaseous.

@Kay-jay. About Newton's Laws. Action/reaction etc... Did you know that know this has been turned on its head. It has something to do with the race for finding absolute zero-0 degrees Kelvin and reactions found in those experiments. And in turn it's creating havoc with all kinds of accepted philosphies from Decarte to Aristotle. It's fascinating stuff.

 

[quality]

They call them gas laws Boyles, Dalton , Charles etc. but just has be stated a substance can exist as a solid, liquid. vapour or all 3 even plasma.
The good thing about physics is it is they same every time unlike Mrs Smiths cetral heating problem that occured since you fitted thier outside tap

 

[GQuigley67]

now they reckon that nothing is in actual fact a solid, it is just made up of densely packed atoms which makes it seem like it is a solid but in actual fact things can pass through it like other atoms.

Most scientific "Facts" are not actual facts, they are theories, as we evolve we learn more and previous "facts" no longer become facts as they have been proven wrong. Most theories contradict each other aswell so they can not all be laws of physics.

 

[fuzzy]

View attachment 3464

This is a sketch of the hydraulic gradient rig as I remember it! The difference in head seen at each vertical is caused by the friction loss due to flow in the pipe. This rig demonstrates it in a really practical way .. of course there are many formulae and methods to calculate theoretical friction losses in pipework systems but seeing is believing!!

interesting stuff, so if the istern was 10m high ie 1bar pressure, regardless of the length of pipe water would come out, just that te pressure will be minmal once the friction losses have decreased with the reduction in velocity?

so at some point the final pipe would show same pressure

 

[Dan]

Don't mind me while I reply to a few of the threads. We need the new thread pages to be picked up correctly. If this thread isn't current, just visit the plumbing forum and post your own new thread or checkout the other existing threads.