Mathematicians, Engineers or Technical Bods, A Calculation? (1 Viewer)

[Langtoftlad]

I have just acquired a new compact hose & reel...

It's 11.5 metres in length & 15mm in diameter.

Simply, what volume of water do I need to flush through to ensure that the fresh water from the tap is coming out the other end?

Or, in other words... what is the volume of the hose pipe if filled from end to end?

Extra marks for showing your working .

 

[Derbyshire wanderer]

No need as connecting to the tap will leave an air bubble that will work its way to the outlet. Once it splutters you know you are back on fresh supply
Simples

 

[Linda and Steph]

Volume of a cylinder is pi x radius x radius x height

Pi= 3.14 .....
Radius=7.5 mm (d/2)
Height (length)=11.5m = 11.5 x 1000mm

Volume = 2,031,187 cubic mm which is just over 2 litres

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[Gellyneck]

Just over 4 x 2litres bottles worth of either still or fizzy water.

Oooops, just realised you wanted the workings shown. Forgot to take photos of wifey filling the bottles. Sorry.

Damn. Just discovered the hose has got a hole in it! And not the one at the end.

 

[Langtoftlad]

Volume of a cylinder is pi x radius x radius x height

Pi= 3.14 .....
Radius=7.5 mm (d/2)
Height (length)=11.5m = 11.5 x 1000mm

Volume = 2,031,187 cubic mm which is just over 2 litres

Excellent 10/10
And you get a

Thanks a million Linda or Steph .

No need as connecting to the tap will leave an air bubble that will work its way to the outlet. Once it splutters you know you are back on fresh supply
Simples

Also "real world" useful - ta

 

[SIFTA SAM]

Volume of a cylinder is pi x radius x radius x height

Pi= 3.14 .....
Radius=7.5 mm (d/2)
Height (length)=11.5m = 11.5 x 1000mm

Volume = 2,031,187 cubic mm which is just over 2 litres

To be a bit more accurate:-
What ambient air temperature are you assuming, and
are you using MSLP for Atmospheric Pressure?

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[Bailey58]

No need for complicated calculations. Water in the pipe is generally warmer than that from the supply so I wait until it feels cooler, works in the kitchen in the house too.

 

[RogerThat]

Or just run it for a minute or two before using

 

[TheTwoOfUs]

Is it 15mm ID or OD?

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[PhilandMena]

600 Gallons at 6 Deg C at sea level on 29 February 12.00 Grenwhich mean time. When the wind is from the West.

 

[Gellyneck]

Is it 15mm ID or OD?

And does the 11.5m include or exclude the tap fitting and nozzle?

 

[Lenny HB]

Volume of a cylinder is pi x radius x radius x height

Pi= 3.14 .....
Radius=7.5 mm (d/2)
Height (length)=11.5m = 11.5 x 1000mm

Volume = 2,031,187 cubic mm which is just over 2 litres

Nope, that is working it out with the outside diameter of the hose he needs to give us the internal diameter.

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[Linda and Steph]

Nope, that is working it out with the outside diameter of the hose he needs to give us the internal diameter.

Ok, a quick search shows the nominal internal diameter to be 12.7 mm:

 

[jockaneezer]

The flow of water will be slower next to the hose wall (boundary layer effect), to allow for complete flushing, you may have to consider Prandtl's concept too

 

[magicsurfbus]

Don't even get started on Einstein's Special Theory of Grey Water Disposal Dynamics - we'll be here all night.

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[pappajohn]

Don't worry about it...it won't kill you.

 

[Chris]

9

 

[Mikeco]

And if you stick your finger over the end of the pipe it will expand, new calculations required.

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[Arewethereyet]

Lost the will to live now

 

[funflair]

Ok, a quick search shows the nominal internal diameter to be 12.7 mm:
View attachment 148627

If 12.7 is the internal diameter the calculation should be pi x d2/4

sorry can't make it look nice.

Martin

 

[gus-lopez]

You need 8' of water , 6" in diameter but funelled.

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[PhilG]

Twenty past Seven

 

[hilldweller]

Excellent 10/10
Thanks a million Linda or Steph .

Also "real world" useful - ta

OK so you now know 2l, so what, are you going to fill it with a measured jug ?

 

[Lenny HB]

Sod the masth, fill the hose with water & empty it into a measuring jug.

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[philw111]

9

What do you mean - 9? Don't you know that the answer to life, the universe and everything is 42 - even more simples!!

 

[jdk62]

Who cares....!

 

[Emmit]

Just over 4 x 2litres bottles worth of either still or fizzy water.

Oooops, just realised you wanted the workings shown. Forgot to take photos of wifey filling the bottles. Sorry.

Damn. Just discovered the hose has got a hole in it! And not the one at the end.

Is it at the 'other end'

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[rangi]

Rubbish! absolute Boulderdash!

You forgot to factor in, the fact Mercury was in ascendance over Venus, Pluto is inline with Cyrius, and the Vauxell Astra down the road is on fire!

Huh bloody amateurs!

 

[philw111]

Who cares....!

About what?

 

[Langtoftlad]

OK so you now know 2l, so what, are you going to fill it with a measured jug ?

Sometimes the pursuit of knowledge for knowledge's sake is a worthwhile aim ... It's a bonus if that knowledge is actually useful .

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