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

[WaterTight]

Is pressure less, by some infinitesimally small amount, at the end of a pipe run, say at a tap, than at the beginning, say at the internal stopcock? Because the pressure available to push water out of the stop-cock is less than the pressure available to push the water out of the tap, because it was finite to begin with so the further away you get from the source of pressure and the greater the amount of water said pressure is trying to shift the less the effect of the pressure and so the less of the residual pressure that is left....?

And if it is - if you ran a pipe, from the stopcock, in a straight line, level for a, for argument's sake, potentially inexhaustible distance in miles - if there was sufficient water to fill this pipe all the way up until the point of exit but the pressure as the stopcock was just normal mains pressure, would you reach a point where nothing would come out the other end? Because the pressure wasn't great enough to move the water through the pipe? And is there a calculation to work out what this would be? It's much easier to think about water being pumped upwards when gravity is fighting you and the limitations there.. Just wondering if it's was in a straight line..

If this effect does exist and doesn't actually require very long distances before it can cause problems I guess it would be part of the calculations used for commercial plumbing. I only thought because there's another thread about running a pipe for an outside tap for 25metres. Made me think how long you'd have to run a pipe on mains before it was too long to work.

 

[Howsie]

In short, yes. The frictional resistance of the pipe wall and that of the water itself increase over distance. I'm sure if you had the time and inclination it could be worked out.

 

[fuzzy]

standing pressure remains the same

there is a friction loss that will reduce pressure and flow rate

 

[Plumbstar Tom]

I'm pretty sure water can be compressed so it would take the mass of water into consideration in the undefined length of pipe

 

[WaterTight]

That's what I was thinking, the mass of the water surely has an effect on the pressure and so enough water = no workable pressure?

 

[Howsie]

Water is not very compress able at all. Even at the bottom of the deepest ocean(4 kilometres) its volume reduces by approx 1.7%.

 

[leelister6]

Would it be cheaper to use copper or plastic pipe for this experiment?!

 

[fuzzy]

didnt think you could compress a liquid?

 

[diamondgas]

Water is a hydralic fluid and can't be compressed, the pressure will be the same it's full length and will flow at a constant pressure. Factors that'll effect it will be gravity! If you're going vertical then the pressure requires to move the water becomes more of a factor as weight then has to be taken into account! The pressure then will be noticibly different allong it's vertical height! They are my first thoughts anyhoo's .. I'm sure someone will google it! A fluid acts in a totally different way to a gas regards pressure..

 

[diamondgas]

So I googled it and found this Pressure Drop Along Pipe Length - Fluid Flow Hydraulic and Pneumatic, Engineers Edge ....... Now you can calculate the length I think? Good luck! LOL

 

[fuzzy]

well thats cleared it up lol

 

[WaterTight]

See I might be imagining it wrong but it doesn't need to be compressable to still have the effect I'm thinking of. I almost imagine it like a queue of molecules. The force at the start - and the fact it can't be compressed - pushes everything out. But it still has mass and it still has to be pushed by that force which is finite. So in my head it still seems like the mass of water, if substantial enough over a long enough run could theoretically counter the force at the beginning and create a stand-still?

So I googled it and found this Pressure Drop Along Pipe Length - Fluid Flow Hydraulic and Pneumatic, Engineers Edge ....... Now you can calculate the length I think? Good luck! LOL

No. No I can't. I'm nowhere near clever enough. I notice it doesn't list the weight of the water as a factor that can fight the pressure though. So maybe I'm wrong. In my hypothetical experiement it would be best to suppose that the pipe causes no friction.

 

[LegionellaSlave]

Plumbing really is rocket science!
We should all pat ourselves on the back :yesnod:

 

[unguided1]

Stuff the water what about if you use Dyhdrogen Monoxide that stuff can be leathal if compressed to much !!!!!!!!!!!!

 

[WaterTight]

just google that....daaaangerous stuff indeed