ok clever peeps.
ive got a plastic tube,its got a 180 degree bend at the bottom (u shape) and its full of water ,i am trying to push it down a hole in the ground (6" dia) that is full of a fluid that is much denser than water therefore the tube rises to the surface when you let it go.
the tube isnt very rigid so pushing it down makes it bend and its got to go down 100 meters into said liquid.
ive been told it needs a 70 odd kg weight to make it sink to the bottom of the hole.
any ideas how to get the tube down and make it stay there?

Hang a weight off the bottom of it to pull it down? Would need to be somewhat more than 70kg to counteract the bouyancy from whatever the dense fluid is.

If you didnt put the water in til afterwards would the liquid compress the tube forcing the air out and making less bouyant allowing you to use a smaller weight o get the ermpty tube down - although if you then fill it up it would become bouyant again

or get a few sets of drain/chimney rods -attach one end to the loop and push it down addind new rods as you go. Measure and count the rods and you know how deep you are.

probably all arse im afraid

Conrod that's a f*ck of long way down?? If it's a borehole try these guys their website might inspire or you could always give them a ring to discuss - -www.wbadmorgan.co.uk
Cheers, Pewe

If it's not held down by a 70kg weight at the bottom, then it's going to be exerting a 70kg force on whatever is restraining it at the top. If the tube is that flexible then it's surely likey to buckle under that sort of force?

Can the water in the tube be replaced by the "stuff" in the hole temporarily?

Mat (long time no see) has the general idea,but we need something that is 70 kg ish and 6" dia max,uranium would fit the bill but a bit dodgy to handle i would have thought,steel/concrete etc takes up too much space,tube wont compress,its pretty rigid,its not a borehole (well) as such,its for geo thermal heating,personally i,d just put a jumper on if it got cold
Mike,no can do on that (my idea first)as it goes all stringy and would impede (long word for a friday) the flow of water

[Edited on 1/6/07 by theconrodkid]

Any idea of the relative densites of the liquid? And the weight of the pipe? Otherwise, just attcj a flipping great rock tyo it and let go. If all the pipe doesn't disappear, you need a bigger rock!

Pump out 6" hole first?attach weight to pipe with u bend,lower in.then refill hole?

Get some drain rods with a hook on the end and put them inside the U to push it to the bottom of the hole and hold it rigid. When it's at the bottom and held you can remove the rods in sections or leave them there

[Edited on 1/6/07 by Peteff]

Dark matter, that weighs a fair bit for its size. Afraid I couldn't point in a direction to get it though.

Sorry, not very usefull!

[Edited on 1/6/07 by andylancaster3000]

cant prod it down with rods,its 100 meters,thats over 300 feet for us olduns
antimatter!!!!!! now theres a though,just need to build a spaceship for £250 and go where no man has set foot before

<Maths hat on>

Let's say you want 100kg.

Steel is 8000kg / m^3 so you need 0.0125 m^3

You say the hole is 6" dia, so let's say we will use a steel weight of dia 4" = 0.1m

the length of the weight will need to be 0.0125 / (pi * 0.1 * 0.1) = 400mm

Not too bad really, but where can you get such a thing? Maybe time to start melting down some pintos

Another option might be to distribute some mass along the pipe so that its effective density is greater than the fluid. Maybe cable-tie fishing weights or something similar at regular intervals? Guess you'd need about 1-2kg per metre.

How about wrapping the tube with some lead flashing type stuff, in a spirawrap type fasion.
Bit of a waste of good lead I suppose and not that grean, but if a job needs doing..............

Diving weights?

buy some 4in drainpipe or what ever size you need to fit the tube into to use as a cast.then put the tube in it then fill with with waterproof concrete that they use for ponds from your local garden center
adam

you could even mould some discs and space them with drain pipe but drill holes in the spacer tubes so the liquid can still heat the pipe

[Edited on 1/6/07 by oadamo]

[Edited on 1/6/07 by oadamo]

cheers for all the replies peeps,looks like the concrete one may work,cant use lead on grounds of chemical reaction/cost,we have a lot of these holes to do and they can go into the water table,anywqay....ITS THE WEEKEND!

what about using copper pipe or something else rigid + weighty?

seen the price of copper,the pipes are 100 meters long and on a roll,as said before they can intrude into the water table and need to be inert like plastic

How did you dig the borehole? what diameter is it, what did you use to get down that far?

we use a drill,like they do drilling for oil,the cutting bit is a gnats under 6"

I think what he's getting at is this: whatever went that far the first time, can go there again surely? IE remove drill bit, attach tubing, chuck it in the big hole in the floor. Jobs a good 'un. Or something like that.

not as simple as that Si,the hole is full of liquid that stops the sides collapsing and to cool/lubricate the drill bit,it so thick the tube wont sink under its own weight and its not possible for 3 lardy people to push said tube down the hole,looks like concrete boots for the poor fella

http://www.dando.co.uk/ look at mtec 6,thats the very drill,fortunately i,m not in the pics

[Edited on 2/6/07 by theconrodkid]

The computer I'm using is too rubbish to upload the pics, so I have no idea what it looks like!
Since I can't see it, what does the drill bit attach to? Can that be adapted to clamp the tube/push it down the hole?

nope,its like a tower with a motor on top that spins a shaft that the drill bit is attached to,maybe someone else could post the pic as i,m a numpty

Is the twisting action of the drill which draws it down, or is it pushed?

gravity and another motor can be used to push the drill bit down the hole

So what stops you using the second motor and the drill to psuh it down the hole? Or is the shaft too big to fit with the pipe?

aha i see what your geting at Si,there wont be enough room,and its 100 meters .each rod is 1.5 meters long,takes hours to unload them as it is,cheers for the idea anyway,think we will have to go with the concrete boot idea