Plumbers physics?

[ChrisR]

Still took 23 mins to look it up though

Beeky chugger. I've got all these letters after my name says I can do this stuff!
But why Mr Brown wanted decreasing pipe diameter I can't understand!

 

[Stevey]

WOW!! The ball cock in those reservoir cisterns must have been huge, wouldn't last two minutes in this day and age, scrap prices being as high as they are and all...

 

[doitall]

Still took 23 mins to look it up though

Beeky chugger. I've got all these letters after my name says I can do this stuff!
But why Mr Brown wanted decreasing pipe diameter I can't understand!

 

[Gasguru]

This place was just up the road from me until it burnt down.

Note one of the two water towers in the background (designed by Brunel but removed in WW2). These stood 85m high holding about 1,400,000 litres.

They fed the 12000 jets of the fountains (2 reached heights of 70m) at a rate of 550,000 litres a minute. ie the fountains didn't run for very long until the water was depleted.

The water was collected in holding reservoirs to be pumped back up the towers.

 

[Agile]

But why Mr Brown wanted decreasing pipe diameter I can't understand!

He probably thought that it reduced the frictional losses but where the pressure was higher near the bottom it was less important!

Tony

 

[Terrywookfit]

Probably a lot cheaper and easier than 24" to feed 1/2" jets!!

Maybe same reason why we dont take 35mm to a 600mm rad!!

And it worked!! Without pumps ,250years ago

Proper plumbing that is !!!

 

[oilman]

Still took 23 mins to look it up though

Beeky chugger. I've got all these letters after my name says I can do this stuff!
But why Mr Brown wanted decreasing pipe diameter I can't understand!

I'm sure you can. He was dealing with a dynamic situation and converting kinetic energy into height of fountain. The OPs question and subsequent answers relate to a static situation.

 

[chrishutt]

...where the pressure was higher near the bottom it was less important!

Does it really make any difference, Tony?

The object of such an exercise is to reduce frictional losses on the run to maximise dynamic pressure at the fountain nozzle, so producing more forceful spouts of water.

If there is increased frictional loss from a section of smaller pipework it makes no difference where it is in the run, whether high up near the feed tank or low down near the fountain nozzle. The pressure loss equation remains the same.

 

[ChrisR]

ONly reason I can think of, and I'm not sure it would make any difference or not, is a gradual reduction might have a lower aggregate resistance than a quicker one.
Certainly the pipes would reduce in size as they get to each of several nozzles, I was thinking of only one fountain.

 

[Agile]

...where the pressure was higher near the bottom it was less important!

Does it really make any difference, Tony?

The answer is that I dont know!

We need Sanji Vara to tell us it does not which would usually mean that it does!

In a horizontal pipe I agree that it does not, Chris H. However, in a vertical pipe with a downward flow then gravity is working on the water?

I have a feeling that quite possibly where the pressure is higher a smaller diameter pipe will suffice. You use 15 mm for mains water and 28 mm for cistern water. So why not???

Some of these people were quite clever a long time ago.

Tony

 

[kirkgas]

i must be in the chaff group