Alternative Power sources - OT and theory. Limit on siphons

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OT and theory. Limit on siphons

harry k

2005-09-20, 8:21 pm

Is there a height limitation on a water siphon, i.e., spring on one
side of ridge, house on other, how high can the ridge be before a
siphon won't work?

I think it can exceed the normal straight suction limit of aprox 34 ft
(sea level) provided you can fill the pipe first but can't find it in
google and can't figure a reasonable experiment.

2nd part: Buddy claims a siphon won't pass through a dip over 34 ft.
That I maintain is BS but again I can find no google info.

Harry K

Vaughn

2005-09-20, 9:21 pm

"harry k" <turnkey4099@hotmail.com> wrote in message
news:1127257649.056722.301810@g49g2000cwa.googlegroups.com...
> Is there a height limitation on a water siphon, i.e., spring on one
> side of ridge, house on other, how high can the ridge be before a
> siphon won't work?
>
> I think it can exceed the normal straight suction limit of aprox 34 ft
> (sea level) provided you can fill the pipe first but can't find it in
> google and can't figure a reasonable experiment.
>
> 2nd part: Buddy claims a siphon won't pass through a dip over 34 ft.
> That I maintain is BS but again I can find no google info.

Interesting question. First, we need to figure out what water column
equals atmospheric pressure. A quick Google tells me that an inch of water
column = 0.03609, lbs./sq. in. So 14.8 PSI would be 410 inches which comes to
34.17 feet. So the most that a siphen can pull is something less than 34 feet.
However, a very small boost pump at the inlet could make all the difference.

Vaughn

>
> Harry K
>

Derek Broughton

2005-09-21, 10:21 am

harry k wrote:

> Is there a height limitation on a water siphon, i.e., spring on one
> side of ridge, house on other, how high can the ridge be before a
> siphon won't work?
>
> I think it can exceed the normal straight suction limit of aprox 34 ft
> (sea level) provided you can fill the pipe first but can't find it in
> google and can't figure a reasonable experiment.
>
> 2nd part: Buddy claims a siphon won't pass through a dip over 34 ft.
> That I maintain is BS but again I can find no google info.
>
I can't believe the answers you've got, some from people with a clue.

You can not raise water more than ~34' over its original level by suction.
That certainly doesn't apply to part 2. You can run a hose down a 100'
cliff and 50' up the other side and it will come out gushing.

I can't point you to a citation that says you can't run a pipe over a 50'
hill using suction, but I'm prepared to join you in the bet that as long as
(a) you fill the pipe first (which you said) and (b) the outlet is below
the inlet, it will flow - and the intervening height is irrelevant.
--
derek

Ecnerwal

2005-09-21, 11:21 am

In article <ql0803-ab9.ln1@othello.pointerstop.ca>,
Derek Broughton <news@pointerstop.ca> wrote:

> I can't point you to a citation that says you can't run a pipe over a 50'
> hill using suction, but I'm prepared to join you in the bet that as long as
> (a) you fill the pipe first (which you said) and (b) the outlet is below
> the inlet, it will flow - and the intervening height is irrelevant.

Wrong, though I can't easily provide you with a cite (it's such basic
science I can't imagine any current papers being written on it) but you
can demonstrate it to yourself easily enough with a vacuum pump (boiling
water at room temperature, or even boiling ice-water), which I've done
numerous times. With patience and enough pipe and terrain you could
demonstrate it to yourself in the wild, too, but I doubt anybody cares
to spend the time and money...I guess a 50 foot roll of clear
vacuum-rated tubing, a bucket of water, a plug for the end, and a 3 or 4
story building would be about the cheapest way to demonstrate, if you
accept the void in the tubing as proof that the siphon won't work -
otherwise you'll need a 100 foot tube and a couple of buckets, so you
can set up the siphon, make it run, and then pull up the middle of it
until it does not. Most garden hose won't work, as that will collapse
under the vacuum, generally long before the water would boil from it.

The problem with up is that the "water filled" tube won't be - even if
the water is perfectly de-gassed (which it won't be) it will boil,
filling the pipe with gaseous water vapor in the region from ~34 feet
(10 meters) to 50 feet to ~34 feet, breaking the siphon. In practice,
due perhaps to dissolved gasses, and perhaps to inability to form a
perfect vacuum with a pump that can move water, pumps tend to be limited
to a suction lift of ~27 feet (8 meters). And I can tell you from
experience with moving beer that lots of dissolved gas can easily break
a siphon in as little as 2-1/2 feet (.75 meter) up.

Down and back up is limited only by the pressure rating (and lack of
leaks) in the pipe, so long as no part of the up is more than 30 feet or
so above the inlet.

--
Cats, coffee, chocolate...vices to live by

Ed Earl Ross

2005-09-21, 12:21 pm

Ecnerwal wrote:
> In article <ql0803-ab9.ln1@othello.pointerstop.ca>,
> Derek Broughton <news@pointerstop.ca> wrote:
>
>
>
>
> Wrong, though I can't easily provide you with a cite (it's such basic
> science I can't imagine any current papers being written on it) but
<snip>

I agree with Ecnerwal.

Water wells are classified as shallow (less than 25') and deep.
Shallow wells can use a jet pump that is mounted above ground. Deep
wells must have the pump at the bottom of the well. The reason is
that a jet pump cannot suck water up a pipe that is too long.

http://www.popularmechanics.com/hom...ks/1275136.html

This isn't a scholarly reference, but it is doubtful any research
is being done today.

--
Humbly--Ed

"If the man doesn't believe as we do,
we say he is a crank, and that settles it.
I mean, it does nowadays, because now we
can't burn him." (Mark Twain)

Derek Broughton

2005-09-21, 12:21 pm

Ecnerwal wrote:

> In article <ql0803-ab9.ln1@othello.pointerstop.ca>,
> Derek Broughton <news@pointerstop.ca> wrote:
>
>
> Wrong, though I can't easily provide you with a cite (it's such basic
> science I can't imagine any current papers being written on it)

If it's so basic, how did you get it wrong?

> but you
> can demonstrate it to yourself easily enough with a vacuum pump (boiling
> water at room temperature, or even boiling ice-water), which I've done
> numerous times. With patience and enough pipe and terrain you could
> demonstrate it to yourself in the wild, too, but I doubt anybody cares
> to spend the time and money...I guess a 50 foot roll of clear
> vacuum-rated tubing, a bucket of water,

A 50' tube wouldn't be close to enough. Since theoretically, with a vacuum,
you can raise the water lever ~34', you need to have at least ~70' of hose.
Say 34.5' _up_, 34.5' _back down_ and another foot below that. You, might,
in fact, demonstrate that you couldn't lift it that much, but you wouldn't
have proved why.

> pumps tend to be limited
> to a suction lift of ~27 feet (8 meters).

You're addressing the wrong problem. _Everybody_ knows that you can't lift
water higher by suction. The question is whether a siphon is the same.

For the record, I've changed my mind. Google's a wonderful thing and
"syphon height" returns an excellent Wikipedia reference.

> And I can tell you from
> experience with moving beer that lots of dissolved gas can easily break
> a siphon in as little as 2-1/2 feet (.75 meter) up.

It's hardly the same situation. Water can generally be made to flow fast
enough to carry bubbles with it. I have enough trouble siphoning beer into
bottles with a 0.5 meter lift - but the trick is always to keep it moving
fast enough.
--
derek

Arnold Walker

2005-09-21, 5:21 pm

On the jet pump....that depends on where the jet is....in the pump for
single pipe or the footvalve for double pipe.
"Ed Earl Ross" <edearl@satx.rr.com> wrote in message
news:lkeYe.26545$S26.5435@tornado.texas.rr.com...
> Ecnerwal wrote:
50'[color=darkred]
as[color=darkred]
> <snip>
>
> I agree with Ecnerwal.
>
> Water wells are classified as shallow (less than 25') and deep.
> Shallow wells can use a jet pump that is mounted above ground. Deep
> wells must have the pump at the bottom of the well. The reason is
> that a jet pump cannot suck water up a pipe that is too long.
>
> http://www.popularmechanics.com/hom...ks/1275136.html
>
> This isn't a scholarly reference, but it is doubtful any research
> is being done today.
>
> --
> Humbly--Ed
>
> "If the man doesn't believe as we do,
> we say he is a crank, and that settles it.
> I mean, it does nowadays, because now we
> can't burn him." (Mark Twain)

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Ecnerwal

2005-09-22, 12:21 am

In article <cd8803-rra.ln1@othello.pointerstop.ca>,
Derek Broughton <news@pointerstop.ca> wrote:

> If it's so basic, how did you get it wrong?

I didn't, but I'm not going to bother explaining it to you any more. The
pressure in any section of siphon which is more than ~34 feet above the
inlet is incompatible with liquid water. While you might manage to move
gas bubbles through a 33 foot lift, you won't be moving any liquid water
through a zone of vacuum where water can not be a liquid.

--
Cats, coffee, chocolate...vices to live by

Anthony Matonak

2005-09-22, 1:21 am

Ecnerwal wrote:
> Derek Broughton <news@pointerstop.ca> wrote:
>
>
> I didn't, but I'm not going to bother explaining it to you any more. The
> pressure in any section of siphon which is more than ~34 feet above the
> inlet is incompatible with liquid water. While you might manage to move
> gas bubbles through a 33 foot lift, you won't be moving any liquid water
> through a zone of vacuum where water can not be a liquid.

I've heard some folks have managed to suck water up more than 33 feet
using some kind of pulse pumping to change the water into a kind of
foam. It's still the same amount of water as would fill a 33 foot
vertical pipe but it occupies more than 33 vertical feet because of
all the bubbles. I'm not at all sure how practical this is.

Anthony

Derek Broughton

2005-09-22, 10:21 am

Ecnerwal wrote:

> In article <cd8803-rra.ln1@othello.pointerstop.ca>,
> Derek Broughton <news@pointerstop.ca> wrote:
>
>
> I didn't, but I'm not going to bother explaining it to you any more.

What you got wrong was answering the wrong question
--
derek

Bob Adkins

2005-09-23, 8:21 am

On 20 Sep 2005 16:07:29 -0700, "harry k" <turnkey4099@hotmail.com> wrote:

>Is there a height limitation on a water siphon, i.e., spring on one
>side of ridge, house on other, how high can the ridge be before a
>siphon won't work?

The problem is getting the siphon started.

Suction (on Earth) is limited to ~26 feet.

If you can "push" the water to the top of the siphon, there is no limit on
how high the obstacle can be.
--
Bob

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