Starting a Syphon that has 60 feet of water pressure above it

[Frigbob]

Hi there,

I'm after some advice on whether it might be possible to start a syphon drain going that has 60 feet of water pressure above it. Basically I want to utilise a natural water collection area to clean down part of a cave underground, which is 60 feet beneath. I have some hosepipe that is "non-collapseable" around its diameter. Ideally I want to get some sort of pump on the user (lower) end of the pipe, crank away, and after a few minutes of work water should come gushing out.

Has anyone got any experience of this kind of thing which they could share? Are there any good types of hand pump which anyone can recommend, ideally that interface with standard diameter hosepipe?

Any advice gratefully received, or alternative technique suggestions.

Frigbob

[Brains]

I would have thought the most critical element would be the height of the sill the water has to be raised over before it can tumble down the pipe. The horizontal distance of the sill would also be an issue perhaps. If the above two are not to great and the pipe not that big, suck it and see! Just be carefull not to have a full body washout 
If access at the top is easy then use a half barrel as a funnel and the other as a bucket, three or four good fills should get it going nicely. Pumps tend to get clogged and broken quite easily. Where are you thinking of hosing down?
Good luck

[robjones]

Recall reading that 28 feet is the practical limit for a siphon. The oft-quoted 32 feet is in a hydraulically perfect, frictionless, etc. world that does not exist in reality, least of all in a cave.

[Les W]

If you coil the hose completely under water and expel all the air, block the ends and then set your siphon, then once you unblock the ends the siphon will start automatically. No need to suck or pump.
If you can't submerge all the pipe then a funnel on the top end and a bung at the bottom, fill it with water via the funnel and then place the top end into the pool and release the bung which will have the same effect. 

I presume what you were trying to say is that you will have a head of 60 feet, not that you were trying to siphon 60 feet which of course is impossible on earth with water.

[SamT]

wot les said..

I think the critical measurement is the distance in height that your pipe has to rise up above the level of your water source before turning and travelling down to the 'user' end as you put it.

If this height is more than 28-32 feet, then it wont syphon because 'cavitation' will occur, this is where the negative pressure (i.e. suck) on the water becomes too great and the water vaporises into a gas and the syphon breaks.

The distance the travelled down is not so important so long as its further then the height travelled up.

However, if the height difference is large, i.e. your gonna get a huge sucking effect, and your pipe wall is not stiff enough, the pipe may collapse causing a constriction. This will at best, seriously reduce the flow and in all probability stop it from working all together.
 
Horizontal distance is far less important. If you have a marginal height difference, and a narrow pipe, then friction losses along the length of the pipe could stop the syphon from working. This can be over come by installing a larger diameter pipe.

I love syphons me, int syphons brrriilliant.

[Peter Burgess]

Hi Frigbob. An interesting name. Is this a project in a Bathstone quarry? I agree that one of your challenges is going to be stopping the hose wall collapsing. Good luck!

[khakipuce]

Wot RobJones said. You can only "suck" water up about 28 feet. The reason for this is that you are creating a lower pressure above the water and atmospheric pressure pressing on the water at the open end pushes it up the pipe. Atmospheric pressure is typically about 1000mB (milli Bar) which is about 10m of head. So atmospheric pressure can only "push" water around 10m up a pipe.

On the other hand you can lift water up any height given a powerful enough pump.

[SamT]

So atmospheric pressure can only "push" water around 10m up a pipe.
On the other hand you can lift water up any height given a powerful enough pump.

I think that should read something like,

So atmospheric pressure can only "push" water around 10m up a pipe.
a pump can "push" water up any height given the pump is powerful enough.

Just trying to clear up any ambiguity. 

[Hughie]

Wot RobJones said. You can only "suck" water up about 28 feet. The reason for this is that you are creating a lower pressure above the water and atmospheric pressure pressing on the water at the open end pushes it up the pipe. Atmospheric pressure is typically about 1000mB (milli Bar) which is about 10m of head. So atmospheric pressure can only "push" water around 10m up a pipe.

On the other hand you can lift water up any height given a powerful enough pump.

Surely he's not going to "suck" the water - if there's a 60' head?

As Brains said - the syphon bit only needs to lift over the sill. After that gravity takes hold. Easily avoid cavitaion by restricting the exit of the pipe. No problem with the pipe wall collapsing - just make sure you acquire suction pipe (the ribbed stuff). Alkathene water pipe is also pretty tough stuff and, like the suction pipe, is available in pretty much whatever size you want. Garden hosepipe stuff is shite.

[owd git]

you jus' need a right sucker, should be a few candidates reading this
 O. G.

[AndyF]

Use hardwall (blue polyprop) water pipe. It won't collapse.... and its farily cheap from an agricultural/builders merchant.

You need a tap on the bottom and a T piece and tap near the top.... Close bottom tap, use a funnel and jug to fill the pipe from the top. Close filling point, open bottom tap...away you go.. 

[Frigbob]

Hi all,

Many thanks for the comments and suggestions. As most people have spotted, the critical factor is the height of the lip between the surface of the water reservoir and the wall containing the waterr. Fortunately this is no more than two feet so we won't be fighting against the laws of physics in terms of what "uphill" distance must be gained from one atmosphere of pressure.

Now all we need to do is to get some more hosepipe since only half of the plumbing is in place. I shall post again with details as to how it all went once the installation is complete!

Thanks,

Frigbob
(it's not a stone mine project, but I do like them hence the username!)

[AndyF]

What region are you in - I have some blue pipe spare for anyone wanting to collect it...

[Frigbob]

Andy,

Sadly I'm nowhere near Matlock, being in the Mendips.

Frigbob.

[Ship-badger]

You need a tap on the bottom and a T piece and tap near the top.... Close bottom tap, use a funnel and jug to fill the pipe from the top. Close filling point, open bottom tap...away you go.. 

This is exactly as we have been doing it in our dig, and it works very well. The great drwback of this "washing" system is that, unless you are lucky enough to be washing the silt into a streamway, which you won't know yet will you; then you will probably one day have to remove all the silt from wherever you washed it to. We have discovered this the hard way. It is very satisfying blasting mud and silt away though, especiaslly if you have a 50m head of water as we do. If there are any joints in your pipe make sure they are good, as we had one fail once and the digger at the bottom got very wet.

[Graigwen]

I am late coming to this topic, and most of the good tips have already been mentioned.

When I used to set up a lot of syphons, usually to drain flooded mines but sometimes to feed drilling rigs I used alkathene piping with an OD of about 2". As access to the water was often a bit awkward but water surface to sill height was only a few feet, I used a short length of pipe laid over the sill and with one end submerged and the other end lower, fitted with a coupler, with a rag at the wet end on the end of a wire though the pipe. Wind the end of the wire round your glove and run downhill and the syphon should start nicely, then couple up as much more pipe as you need (it was convenient to have a stopcock on the top end of the extension - maybe this is why we never had any problems with the original air in the extension pipe).

It is good fun playing with syphons with large heads. A syphon with a couple of hundred feet head on Snowdon had enough power to blow the string of drill rods out of a hole drilled at the bottom end, never had any problem with cuttings blocking the hole!

.

[SamT]

This is exactly as we have been doing it in our dig, and it works very well. The great drwback of this "washing" system is that, unless you are lucky enough to be washing the silt into a streamway, which you won't know yet will you; then you will probably one day have to remove all the silt from wherever you washed it to. We have discovered this the hard way. It is very satisfying blasting mud and silt away though, especiaslly if you have a 50m head of water as we do. If there are any joints in your pipe make sure they are good, as we had one fail once and the digger at the bottom got very wet.

Agreed, wasn't a water blasting style dig in Peak cavern stopped because the sheer quantity of mud being washed away was creating a horrendous mess in all sorts of ways. Flowing into sumps causing vis issues for divers not to mention gallons of gloop getting traipsed all over the cave.

If such a system is going to be used, careful consideration should paid to the knock on effects of the gloop that will be have to end up somewhere.