OT - it is about crabs

[B J Conner]

The picture is bad but it's still interestiing. The poor crab just
disappears.

http://www.digitalfog.com/gallery/crab.htm

[rw]

B J Conner wrote:
> The picture is bad but it's still interestiing. The poor crab just
> disappears.
>
> http://www.digitalfog.com/gallery/crab.htm
>
>

crab juice

--
Cut "to the chase" for my email address.

[Frank Reid]

Always wondered how you make a crab cocktail.
--
Frank Reid
Reverse email to reply

[riverman]

I wonder:
a) what the guy at the other end of the pipe thought that greygreen
chunky sludge was that come through the pipe
b) what that pipe carried
c) how it kept from collapsing when the structural integrity was
compromised by the saw. Thats a lot of PSI, as the crab will attest.

--riverman

[asadi]

"riverman" > wrote in message
oups.com...
>I wonder:
> a) what the guy at the other end of the pipe thought that greygreen
> chunky sludge was that come through the pipe
> b) what that pipe carried
> c) how it kept from collapsing when the structural integrity was
> compromised by the saw. Thats a lot of PSI, as the crab will attest.
>
> --riverman
>

huh?

[riverman]

Umm, lots of outside pressure on something like a cylinder compresses
it evenly, like squeezing an egg in your hand without it breaking. But
if you compromise ths struture of the the tube, it can implode. Just
wondering how the tube keeps from imploding when they cut into it.

Did I miss something?

Again?

--riverman

[Wolfgang]

"riverman" > wrote in message
oups.com...
> Umm, lots of outside pressure on something like a cylinder compresses
> it evenly, like squeezing an egg in your hand without it breaking. But
> if you compromise ths struture of the the tube, it can implode. Just
> wondering how the tube keeps from imploding when they cut into it.
>
> Did I miss something?
>
> Again?

The list of suitable materials for a pipeline at that kind of depth and
pressure is going to be a very short one. It's safe to assume, I think,
that it's some sort of steel. Can't tell much for sure about the size of
the pipe but assuming the crab is neither a giant nor a pygmy species, and
judging by the hint of curvature in the cut, I'd guess we're looking at
something in the range of several inches to a couple of feet in diameter.
Even at ground level and low pressures pipe that size would have a wall
thickness of 1/4 inch or more. I haven't looked it up, but I'm pretty sure
that 2700 psi is well within the strength limits of just about any steel at
that thickness.

What I find curious is the assertion that pressure inside the pipe is 0
psi. Why (and how, for that matter) would someone generate and maintain a
vacuum in a pipeline at that depth and pressure? Then too, if you pause the
video at just the right point, it looks very much like about half of the
crab gets across the cut with no apparent difficulty before the whole thing
gets sucked in. And then it disappears in large chunks. If the suction is
great enough to make big chunks of crab disappear in a small fraction of a
second, how did it manage to get so far? Shouldn't it have gone in feet
first?

Wolfgang

[B J Conner]

"Wolfgang" > wrote in message
...
>
> "riverman" > wrote in message
> oups.com...
> > Umm, lots of outside pressure on something like a cylinder compresses
> > it evenly, like squeezing an egg in your hand without it breaking. But
> > if you compromise ths struture of the the tube, it can implode. Just
> > wondering how the tube keeps from imploding when they cut into it.
> >
> > Did I miss something?
> >
> > Again?
>
> The list of suitable materials for a pipeline at that kind of depth and
> pressure is going to be a very short one. It's safe to assume, I think,
> that it's some sort of steel. Can't tell much for sure about the size of
> the pipe but assuming the crab is neither a giant nor a pygmy species, and
> judging by the hint of curvature in the cut, I'd guess we're looking at
> something in the range of several inches to a couple of feet in diameter.
> Even at ground level and low pressures pipe that size would have a wall
> thickness of 1/4 inch or more. I haven't looked it up, but I'm pretty
sure
> that 2700 psi is well within the strength limits of just about any steel
at
> that thickness.
>
> What I find curious is the assertion that pressure inside the pipe is 0
> psi. Why (and how, for that matter) would someone generate and maintain a
> vacuum in a pipeline at that depth and pressure? Then too, if you pause
the
> video at just the right point, it looks very much like about half of the
> crab gets across the cut with no apparent difficulty before the whole
thing
> gets sucked in. And then it disappears in large chunks. If the suction
is
> great enough to make big chunks of crab disappear in a small fraction of a
> second, how did it manage to get so far? Shouldn't it have gone in feet
> first?
>
> Wolfgang
>
>
That has to be a natural gas pipeline. The North Sea has some that may be
that deep. The deepest one I remember reading about is the one from North
Africa to Italy. The crab has to have stumbled onto the cut soon after the
operation began. The pipe was probably depressurized for the cut and may
have been purged with nitrogen. Once the cut is opened up the inflow would
only last till the pipe filled up.
Pipeline engineering is at pretty advanced state, crab collapse mechanics
is an untouched science.

[riverman]

Actually, if you look closely (or compare the end and start images),
the entire crab doesn't even get sucked in. A big piece get stuck right
against the saw blade, near where it looks like the saw did a double
cut. My guess is that the whirling saw blade did as much to segment the
crab (or at least break its shell initially) as the 'pressure'.

--riverman

[riverman]

Wouldn't there be bubbles of nitrogen escaping as the water flooded the
pipe?

--riverman

[Mike Connor]

Interesting. Unlikely to become popular as a method for removing crabs
though.

This seems a more promising avenue;

http://www.cdc.gov/ncidod/dpd/parasites/lice/factsht_pubic_lice.htm

TL
MC

[B J Conner]

"Mike Connor" > wrote in message
...
> Interesting. Unlikely to become popular as a method for removing crabs
> though.
>
> This seems a more promising avenue;
>
> http://www.cdc.gov/ncidod/dpd/parasites/lice/factsht_pubic_lice.htm
>
> TL
> MC
>
>
Not the best methods. Any of the ex sailors here can fill you in on the
icepick/gasoline or vodka/sand methods.

[B J Conner]

"riverman" > wrote in message
oups.com...
> Wouldn't there be bubbles of nitrogen escaping as the water flooded the
> pipe?
>
> --riverman
>
Only if the nitrogen or air was at greater pressure than the seawater.

[Wolfgang]

"B J Conner" > wrote in message
news:KPt6f.4640$gF4.776@trnddc07...
>
> That has to be a natural gas pipeline. The North Sea has some that may be
> that deep. The deepest one I remember reading about is the one from North
> Africa to Italy. The crab has to have stumbled onto the cut soon after
> the
> operation began. The pipe was probably depressurized for the cut and may
> have been purged with nitrogen. Once the cut is opened up the inflow
> would
> only last till the pipe filled up.

Whatever flows through the pipe, it makes sense to depressurize and purge it
before cutting. But why nitrogen rather than just air? And why evacuate to
less than atmospheric pressure? As you say, the pipe will begin to fill
with water as soon as the wall is breached.....why not just let it fill
before cutting? Incidentally, I also wonder, is there a way to isolate a
segment of the pipe under water with some sort of shutoff valve, or is the
whole thing contiuous between shore stations?

> Pipeline engineering is at pretty advanced state,

I would expect so.

> crab collapse mechanics is an untouched science.

Well, was, till now. :)

Wolfgang

[Wolfgang]

"riverman" > wrote in message
oups.com...
> Wouldn't there be bubbles of nitrogen escaping as the water flooded the
> pipe?

Not as long as there's a great deal more pressure outside than inside.
Bubbles only escape as gas (whether natural gas, air, nitrogen, or whatever)
is displaced by the water. And, at 0 psig (which is still hard to
believe....and hard to understand even if true) there is no gas to escape.
Some of the water entering the pipe would initially vaporize, of course, but
it would recondense as the pressure inside and outside equalize, and none of
it would escape as a gas either.

Wolfgang

[Wolfgang]

"riverman" > wrote in message
oups.com...
> Actually, if you look closely (or compare the end and start images),
> the entire crab doesn't even get sucked in. A big piece get stuck right
> against the saw blade, near where it looks like the saw did a double
> cut.

Can't see any of it being spewed out by the blade. Big chunks just
disappear.

> My guess is that the whirling saw blade did as much to segment the
> crab (or at least break its shell initially) as the 'pressure'.

Looks that way to me too. But given that there's no evidence of crab bits
escaping, it looks to me like we're expected to believe that the huge
difference in pressure forced all of it through the explicitly stated (and
explicitly reinforced) 3mm width of the cut. Maybe so. Still smells a bit
funny to me.

Wolfgang

[rw]

Wolfgang wrote:
> "riverman" > wrote in message
> oups.com...
>
>>Wouldn't there be bubbles of nitrogen escaping as the water flooded the
>>pipe?
>
>
> Not as long as there's a great deal more pressure outside than inside.
> Bubbles only escape as gas (whether natural gas, air, nitrogen, or whatever)
> is displaced by the water. And, at 0 psig (which is still hard to
> believe....and hard to understand even if true) there is no gas to escape.
> Some of the water entering the pipe would initially vaporize, of course, but
> it would recondense as the pressure inside and outside equalize, and none of
> it would escape as a gas either.

First of all, psig stands for "pounds per square inch gauge" referenced
to ambient air pressure. So 0 psig is just ambient air pressure, not a
vacuum as you seem to be under the false impression.

Secondly, nitrogen gas would not form bubbles at 2700 psi. It would
dissolve in the water. Nitrogen coming out of solution and forming
bubbles is what causes bends (nitrogen narcosis) when scuba divers
ascend too fast, and they're not diving anywhere close to 6000 feet.

--
Cut "to the chase" for my email address.

[Wolfgang]

"rw" > wrote in message
m...
> Wolfgang wrote:
>> "riverman" > wrote in message
>> oups.com...
>>
>>>Wouldn't there be bubbles of nitrogen escaping as the water flooded the
>>>pipe?
>>
>>
>> Not as long as there's a great deal more pressure outside than inside.
>> Bubbles only escape as gas (whether natural gas, air, nitrogen, or
>> whatever) is displaced by the water. And, at 0 psig (which is still hard
>> to believe....and hard to understand even if true) there is no gas to
>> escape. Some of the water entering the pipe would initially vaporize, of
>> course, but it would recondense as the pressure inside and outside
>> equalize, and none of it would escape as a gas either.
>
> First of all, psig stands for "pounds per square inch gauge" referenced to
> ambient air pressure. So 0 psig is just ambient air pressure, not a vacuum
> as you seem to be under the false impression.

I see. But at a thousand fathoms or so, "ambient" air pressure (assuming
one could find enough air to make it worth measuring) would be about
........oh, say, 2700 psi, ainna? Makes it sorta hard to understand how
anything got pushed (or sucked.....depends on point of view) into the
pipe......no? Perhaps you mean what we in the sciences refer to as
"standard" pressure? Or maybe you mean "ambient" pressure at sea level
somewhere more or less nearby at the time the pipe was being sawed. In the
latter case, 0 psig might be interesting to someone, somewhere, I suppose,
but it really isn't very useful for us now, is it?

> Secondly, nitrogen gas would not form bubbles at 2700 psi. It would
> dissolve in the water.

All of it? How fast? Um.....gosh, Mr. Wizard, what exactly is the
solubility of nitrogen in seawater (I think it's safe to assume that we're
not dealing with fresh water here) at roughly 2700 psi and somewhere in the
neighborhood of 0 degrees celsius?

> Nitrogen coming out of solution and forming bubbles is what causes bends
> (nitrogen narcosis) when scuba divers ascend too fast, and they're not
> diving anywhere close to 6000 feet.

No kidding? Well......gosh.

Wolfgang
who notes that google still appears to have limitations. :)

[rw]

Wolfgang wrote:

> "rw" > wrote in message
> m...
>
>>Wolfgang wrote:
>>
>>>"riverman" > wrote in message
oups.com...
>>
>>First of all, psig stands for "pounds per square inch gauge" referenced to
>>ambient air pressure. So 0 psig is just ambient air pressure, not a vacuum
>>as you seem to be under the false impression.
>
>
> I see. But at a thousand fathoms or so, "ambient" air pressure (assuming
> one could find enough air to make it worth measuring) would be about
> .......oh, say, 2700 psi, ainna?

First of all, we aren't talking about 6000 fathoms (36,000 feet). The
crab was sucked into the pipe at 6000 feet.

Secondly, you are confusing water pressure with air pressure. Big
difference. You see, water is much denser than air. (That means it has
more mass per unit volume.) A 6000 foot water column in one G produces
about 2700 psi of pressure. On the other hand, ambient air pressure at
6000 feet (not fathoms) below sea level would be only slightly more than
one atmosphere, which is about 14.7 psi. It would be greater than one
atmosphere by an amount equal to the amount that the ambient air
pressure is less one atmosphere at an altitude of 6000 feet (not
fathoms) above sea level.

This is high school physics for dummies, ainna?

> Makes it sorta hard to understand how
> anything got pushed (or sucked.....depends on point of view) into the
> pipe......no? Perhaps you mean what we in the sciences refer to as
> "standard" pressure? Or maybe you mean "ambient" pressure at sea level
> somewhere more or less nearby at the time the pipe was being sawed. In the
> latter case, 0 psig might be interesting to someone, somewhere, I suppose,
> but it really isn't very useful for us now, is it?

It certainly isn't useful to you because you don't understand the basic
definition of it.

>>Secondly, nitrogen gas would not form bubbles at 2700 psi. It would
>>dissolve in the water.
>
>
> All of it?

Yep.

> How fast?

Microseconds.

> Um.....gosh, Mr. Wizard, what exactly is the
> solubility of nitrogen in seawater (I think it's safe to assume that we're
> not dealing with fresh water here) at roughly 2700 psi and somewhere in the
> neighborhood of 0 degrees celsius?

Why don't you go educate yourself. I don't have the time. I hear that
Wikipedia is an excellent source. Search on "vapor pressure" and you'll
get an explanation of the basic concept. You'll have to do a little more
work to find the vapor pressure of nitrogen at 0 C, but I'm sure that
with some persistence you'll find it, and I'm confident it will be
considerably less than 2700 psi.

Or, you can continue to bloviate in ignorance.

--
Cut "to the chase" for my email address.

[Wolfgang]

"rw" > wrote in message
m...
> Wolfgang wrote:
>
>> "rw" > wrote in message
>> m...
>>
>>>Wolfgang wrote:
>>>
>>>>"riverman" > wrote in message
oups.com...
>>>
>>>First of all, psig stands for "pounds per square inch gauge" referenced
>>>to ambient air pressure. So 0 psig is just ambient air pressure, not a
>>>vacuum as you seem to be under the false impression.
>>
>>
>> I see. But at a thousand fathoms or so, "ambient" air pressure (assuming
>> one could find enough air to make it worth measuring) would be about
>> .......oh, say, 2700 psi, ainna?
>
> First of all, we aren't talking about 6000 fathoms (36,000 feet). The crab
> was sucked into the pipe at 6000 feet.

Hm.....

So, that might provide a clue as to why I stated "a thousand fathoms"?
(hint: see above)

> Secondly, you are confusing water pressure with air pressure.

Nope, not for a second.

> Big difference.

Nope, no difference.

> You see, water is much denser than air.

No kidding?

> (That means it has more mass per unit volume.)

Well, I be go ta hell!

> A 6000 foot water column in one G produces about 2700 psi of pressure. On
> the other hand, ambient air pressure at 6000 feet (not fathoms) below sea
> level would be only slightly more than one atmosphere, which is about 14.7
> psi.

Which, once again, raises the rather interesting question of just where this
"ambient air" IS.......at 6000 feet below sea level. I mean, it's all well
and good for you to review your doctoral dissertation for our amusement
here, but it does us little good in solving what would quickly become a very
pressing problem......for an air breather.

> It would be greater than one atmosphere by an amount equal to the amount
> that the ambient air pressure is less one atmosphere at an altitude of
> 6000 feet (not fathoms) above sea level.

Well, if you mean what you think you do......a leap of faith, to be sure,
but let's run with it......

The average density of an uncontained 6000 foot (not fathom) column of air
extending UP from sea level would be less than that of an uncontained 6000
foot (not fathom) column of air extending DOWN from sea level because the
latter always has the weight of of the former pressing down on
it.....compressing it (you see, compressed air is denser than uncompressed
air). Thus, the change in "ambient" pressure is, in fact, NOT the same for
every incremental change in elevation. In other words, the change in
"ambient" pressure with respect to elevation is, in fact, NOT linear.

> This is high school physics for dummies, ainna?

So it would appear. :)

>> Makes it sorta hard to understand how anything got pushed (or
>> sucked.....depends on point of view) into the pipe......no? Perhaps you
>> mean what we in the sciences refer to as "standard" pressure? Or maybe
>> you mean "ambient" pressure at sea level somewhere more or less nearby at
>> the time the pipe was being sawed. In the latter case, 0 psig might be
>> interesting to someone, somewhere, I suppose, but it really isn't very
>> useful for us now, is it?
>
> It certainly isn't useful to you because you don't understand the basic
> definition of it.

Even after all these years it's sometimes difficult to determine in a
particular instance whether you really don't have any idea of what you've
done to yourself or are simply determined to bury yourself ever deeper in
yet another misguided attempt to baffle with bull****. :)

Just to clear the air (so to speak), I'll explain this as simply as
possible. What SHOULD have leaped out at you the moment you set eyes on the
page at:

http://www.digitalfog.com/gallery/crab.htm

is that the term "0 psig" is absolutely meaningless UNLESS the author(s)
meant to say that there was NOTHING in the pipe. At a thousand fathoms (not
6000......well, actually, it would be true at 6000 too, but I'm damned if I
can figure out why you keep insisting that we deal with such a figure when
there has been no suggestion that it's applicable in this case) THERE IS NO
AMBIENT AIR!! It naturally follows that if there is no ambient air, there
can be no "ambient air pressure". In other words, "ambient air pressure" at
a thousand fathoms (not 6000) in seawater is exactly 0.0 psi in the absence
of air. And since "0 psig" means that pressure inside the system (the pipe,
in this instance) under consideration is exactly equal to that of the
ambient air, the pressure inside the system is exactly 0.0 psi......it is
what we in the sciences call.......wait for it......a vacuum!

>>>Secondly, nitrogen gas would not form bubbles at 2700 psi. It would
>>>dissolve in the water.
>>
>>
>> All of it?
>
> Yep.
>
>> How fast?
>
> Microseconds.

So, a cubic liter of nitrogen will dissolve completely in a cubic liter of
seawater in microseonds? How many microseconds? I mean, a range of 1-40
microseconds as opposed to a range of 6000-36000 might make quite a
difference in some situations, don'tcha think?

>> Um.....gosh, Mr. Wizard, what exactly is the solubility of nitrogen in
>> seawater (I think it's safe to assume that we're not dealing with fresh
>> water here) at roughly 2700 psi and somewhere in the neighborhood of 0
>> degrees celsius?
>
> Why don't you go educate yourself.

I'm trying. That's why I ask you questions.

> I don't have the time.

Well, based on the discussion thus far, it looks like you've already done
the math. How much time can it take to type it out for us?

> I hear that Wikipedia is an excellent source. Search on "vapor pressure"
> and you'll get an explanation of the basic concept. You'll have to do a
> little more work to find the vapor pressure of nitrogen at 0 C, but I'm
> sure that with some persistence you'll find it, and I'm confident it will
> be considerably less than 2700 psi.

I'm not real good at research......and I didn't take high school physics for
dummies. Why don't you just take a moment and explain it all to me in terms
that maybe even I can understand?

Um......do you suppose Henry's law would do us any good here?

> Or, you can continue to bloviate in ignorance.

Well, that's pretty much up to you, I guess. I'm relying on your awe
inspiring mastery of science and your famous generosity of spirit.

Wolfgang
have i mentioned that the boy just WILL NOT learn? :)

[rw]

Wolfgang wrote:

> "rw" > wrote in message
> m...
>
>>A 6000 foot water column in one G produces about 2700 psi of pressure. On
>>the other hand, ambient air pressure at 6000 feet (not fathoms) below sea
>>level would be only slightly more than one atmosphere, which is about 14.7
>>psi.
>
>
> Which, once again, raises the rather interesting question of just where this
> "ambient air" IS.......at 6000 feet below sea level.

Do you think it might be in the pipe, which presumably is connected to
the atmosphere? Saying that the pressure in the pipe is 0 psig is just a
somewhat nerdy way of saying that the pipe is not pressurized (or
depressurized) with respect to atmospheric pressure.

>
> Um......do you suppose Henry's law would do us any good here?

No, Henry's Law is not relevant because the system is far from
equilibrium when the saw pierces the pipe. That's the whole point,
especially from the crab's point of view. What is relevant is the
Rayleigh-Plesset equation that describes the violent collapse of
bubbles, but all you really need (but apparently lack) is a basic
understanding of hydrostatic pressure and vapor pressure.

If a bubble of gas managed to make it out of the pipe (which itself
seems unlikely to me), it would very quickly collapse under the
hydrostatic pressure of 2700 psi, which is enormous compared to the
vapor pressure of the gas. The gas molecules would end up dissolved in
the water.

BTW, bubble collapse is so violent that it can damage a ship's propeller
if the propeller turns fast enough to create a cavity. Bernoulli's law
implies that cavitation is unavoidable at high speed, so cavitation
damage is a limiting factor for the speed of boats.

Also BTW, some varieties of shrimp (so-called snapping shrimp) use
cavitation collapse to stun their prey. The shrimp closes its large claw
so rapidly that it creates a cavity, which then collapses and creates a
shock wave.

--
Cut "to the chase" for my email address.

[~^ beancounter ~^]

bottom line is "water is heavy" esp when you
stack more on more, etc....

[Wolfgang]

"rw" > wrote in message
m...
> Wolfgang wrote:
>
>> "rw" > wrote in message
>> m...
>>
>>>A 6000 foot water column in one G produces about 2700 psi of pressure. On
>>>the other hand, ambient air pressure at 6000 feet (not fathoms) below sea
>>>level would be only slightly more than one atmosphere, which is about
>>>14.7 psi.
>>
>>
>> Which, once again, raises the rather interesting question of just where
>> this "ambient air" IS.......at 6000 feet below sea level.
>
> Do you think it might be in the pipe, which presumably is connected to the
> atmosphere?

Not a chance. Ambient pressure, a critical factor in determining psig is,
by definition, OUTSIDE that system. Common knowledge.

> Saying that the pressure in the pipe is 0 psig is just a somewhat nerdy
> way of saying that the pipe is not pressurized (or depressurized) with
> respect to atmospheric pressure.

Well, for nerds, evidently. For the rest of us (those in the
sciences.......well, and maybe an exceptionally bright engineer here and
there) it's important for determining which way a gas will flow.
Atmospheric pressure, not so incidentally, is only a factor when there is an
atmosphere. In the instant case, using the term loosely, we could say that
the surrounding water passes for an atmosphere, but then psig in the pipe
could only be 0 if the pressure of whatever was inside was about 2700 psi.
But, I have it from a VERY reliable source that psig is "referenced to
ambient air pressure"......note that "air" is mentioned specifiaclly. If,
on the other hand, the atmosphere referred to was the air at sea
level.....or wherever an open end of the pipe might be, then a psig of 0 at
a thousand (not 6000) fathoms would mean that the pressure was the same
there as at the open end. Clearly, this is not the case because the pipe at
the saw cut is at the bottom of an additional 6000 (not 36000) foot column
of air. Any way you cut it, it looks like the folks at digitalfog.com
have no better idea of what psig means than you do. :)

>> Um......do you suppose Henry's law would do us any good here?
>
> No, Henry's Law is not relevant because the system is far from equilibrium
> when the saw pierces the pipe. That's the whole point, especially from the
> crab's point of view.

I'm still not sure I understand why the damned crab is so allfired concerned
about why nitrogen is used to evacuate the remnants of whatever was in the
pipe rather than just air. I mean, if it is indeed a natural gas pipeline
(as BJ speculated) then it would make sense from our point of view because
nitrogen is not an oxidizer......thus, it eliminates the possiblity of
accidental ignition. But I have yet to meet a crab that much gives a ****
about fire at 1000 (not 6000) fathoms. Being sucked through a 3mm slit, on
the other hand, weighs as heavily on their minds at a depth of 6000 feet as
it does at 36000. Obviously (to them, if not necessarily to you) a pipe
chock full of vacuum would (when and if breached) increase the likelihood of
this happening (if they happened to be in the immediate neighborhood) as
compared to.....oh, say one full of whatever at a higher pressure. See?
:)

> What is relevant is the Rayleigh-Plesset equation that describes the
> violent collapse of bubbles,

Bubbles? What bubbles? I have it from an unimpeachable source that there
would be no bubbles because all of the nitrogen in the pipe (however much
that might be at 0 psi) would be dissolved virtually instantaneously by the
seawater rushing in at high pressure and thus, at high speed. Where did
these bubbles suddenly come from?

> but all you really need (but apparently lack) is a basic understanding of
> hydrostatic pressure and vapor pressure.

Teach me.

> If a bubble of gas managed to make it out of the pipe (which itself seems
> unlikely to me),

Well, this is just getting silly. Make up your mind, please. Do we have
bubbles, or don't we?! :(

> it would very quickly collapse under the hydrostatic pressure of 2700 psi,
> which is enormous compared to the vapor pressure of the gas.

Hm......but that would depend to a large extent on what the initial pressure
on the gas might be, ainna? And we don't appear to be getting any closer to
that mysterious value at all, do we?

> The gas molecules would end up dissolved in the water.

All of them? How fast?

> BTW, bubble collapse is so violent that it can damage a ship's propeller
> if the propeller turns fast enough to create a cavity.

Which sort of invites the question of how the hell a ship's propeller got
through a 3mm slit in a pipe at a thousand (not 6000) fathoms.

> Bernoulli's law implies that cavitation is unavoidable at high speed, so
> cavitation damage is a limiting factor for the speed of boats.

Not something we need to expend a lot of worry on, I think. Once they get
the pipe restored it won't make much difference.......boats don't travel
well in vacuum under any circumstances.

> Also BTW, some varieties of shrimp (so-called snapping shrimp) use
> cavitation collapse to stun their prey. The shrimp closes its large claw
> so rapidly that it creates a cavity, which then collapses and creates a
> shock wave.

Well.......gosh.

Wolfgang

[Wolfgang]

"~^ beancounter ~^" > wrote in message
oups.com...
> bottom line is "water is heavy" esp when you
> stack more on more, etc....

Profundity works a whole lot better when accompanied by a clue about who or
what it might refer to and/or where it might be directed.

Wolfgang

[Ken Fortenberry]

Wolfgang wrote:
>
> Profundity works a whole lot better when accompanied by a clue about who or
> what it might refer to and/or where it might be directed.

Never heard of Zen, eh ?

--
Ken Fortenberry

[rw]

~^ beancounter ~^ wrote:

> bottom line is "water is heavy" esp when you
> stack more on more, etc....

You'd think that would be obvious.

I have a game I play from time to time called "catch Wolfgang in a
factual error." It's a guilty pleasure, and I'm not proud of it, but
it's a lot of fun for a short time, kind of like crack cocaine I
suppose. Wolfgang has such an overweening but fragile ego that he can
never admit an error, so he gets deeper and deeper into a complex,
desperate flood of sophistic rebuttals and red herrings, inevitably
introducing more errors. It's really pathetic, and soon becomes more
tiresome than amusing.

--
Cut "to the chase" for my email address.

[Wolfgang]

"Ken Fortenberry" > wrote in message
...
> Wolfgang wrote:
>>
>> Profundity works a whole lot better when accompanied by a clue about who
>> or what it might refer to and/or where it might be directed.
>
> Never heard of Zen, eh ?

Sure I have. But without some sort of reminder I never can remember who he
is (was?). :(

Wolfgang

[Wolfgang]

"rw" > wrote in message
m...
> ~^ beancounter ~^ wrote:
>
>> bottom line is "water is heavy" esp when you
>> stack more on more, etc....
>
> You'd think that would be obvious.
>
> I have a game I play from time to time called "catch Wolfgang in a factual
> error." It's a guilty pleasure, and I'm not proud of it, but it's a lot of
> fun for a short time, kind of like crack cocaine I suppose. Wolfgang has
> such an overweening but fragile ego that he can never admit an error, so
> he gets deeper and deeper into a complex, desperate flood of sophistic
> rebuttals and red herrings, inevitably introducing more errors. It's
> really pathetic, and soon becomes more tiresome than amusing.

Surrender accepted.

Wolfgang
what do you call a biped that has chopped of dozens of feet? :)

[rw]

Wolfgang wrote:
> "rw" > wrote in message
> m...
>
>>it would very quickly collapse under the hydrostatic pressure of 2700 psi,
>>which is enormous compared to the vapor pressure of the gas.
>
>
> Hm......but that would depend to a large extent on what the initial pressure
> on the gas might be, ainna?

No, it wouldn't.

BTW, what's with this "ainna" thing? Is it just a way to appear even
more obnoxious?

>>The gas molecules would end up dissolved in the water.
>
>
> All of them?

Yes.

> How fast?

Real fast. Virtually instantaneously compared to unaided human perception.

--
Cut "to the chase" for my email address.

[rw]

Wolfgang wrote:
>
> Wolfgang
> what do you call a biped that has chopped of dozens of feet? :)

Ungrammatical.

What's the name of the world's largest island in a lake on
an island in a lake?

--
Cut "to the chase" for my email address.

[Wolfgang]

"rw" > wrote in message
m...
> Wolfgang wrote:
>> "rw" > wrote in message
>> m...
>>
>>>it would very quickly collapse under the hydrostatic pressure of 2700
>>>psi, which is enormous compared to the vapor pressure of the gas.
>>
>>
>> Hm......but that would depend to a large extent on what the initial
>> pressure on the gas might be, ainna?
>
> No, it wouldn't.

Yes, it would.

> BTW, what's with this "ainna" thing? Is it just a way to appear even more
> obnoxious?

Bothers you.....ainna? :)

>>>The gas molecules would end up dissolved in the water.
>>
>>
>> All of them?
>
> Yes.

I see.

>> How fast?
>
> Real fast. Virtually instantaneously compared to unaided human perception.

Hm......how fast is unaided human perception? How long, for instance, does
a take a putz to realize what he's done to himself?

Wolfgang
hee, hee, hee.

[Wolfgang]

"rw" > wrote in message
m...
> Wolfgang wrote:
>>
>> Wolfgang
>> what do you call a biped that has chopped of dozens of feet? :)
>
> Ungrammatical.

Most people don't have much trouble recognizing an obvious typo. You ain't
real bright. :)

> What's the name of the world's largest island in a lake on
> an island in a lake?

I dunno.

Wolfgang

[Sarge]

Wolfgang wrote: "I'm still not sure I understand why the damned crab is so
allfired concerned about why nitrogen is used to evacuate the remnants of
whatever was in the pipe rather than just air. I mean, if it is indeed a
natural gas pipeline (as BJ speculated) then it would make sense from our
point of view because nitrogen is not an oxidizer......thus, it eliminates
the possiblity of accidental ignition."

You are correct why nitrogen is used. Nitrogen is used in industry to purge
equipment and pipes to remove hydrocarbons so that when opened to atmosphere
the chance of fire, explosion or chemical contact with employees are
minimized. Nitrogen is also used in many industries to blank (fill vapor
space on top of liquids) tanks and vessels to reduce the chance of a fire or
explosion.

Sarge

[Sarge]

rw wrote: "What's the name of the world's largest island in a lake on an
island in a lake?

Manitou Lake located on Manitoulin Island located on Lake Huron.

Sarge

[rw]

Sarge wrote:
> rw wrote: "What's the name of the world's largest island in a lake on an
> island in a lake?
>
> Manitou Lake located on Manitoulin Island located on Lake Huron.

Wolfgang? Can you supply the correct answer?

--
Cut "to the chase" for my email address.

[Wolfgang]

"rw" > wrote in message
m...
> Sarge wrote:
>> rw wrote: "What's the name of the world's largest island in a lake on an
>> island in a lake?
>>
>> Manitou Lake located on Manitoulin Island located on Lake Huron.
>
> Wolfgang? Can you supply the correct answer?

Um.......Manitou Lake is not an island?

Wolfgang
what i win? :)

[Jeff Marso]

"Wolfgang" > wrote in
:

> What I find curious is the assertion that pressure inside the pipe is
> 0 psi. Why (and how, for that matter) would someone generate and
> maintain a vacuum in a pipeline at that depth and pressure?

The site says it's PSIG not PSI.

from:
http://www.unc.edu/~rowlett/units/dictP.html

"psig is a symbol for pound per square inch gauge; this means that the
pressure has been read from a gauge which actually measures the difference
between the pressure of the fluid and the pressure of the atmosphere"

Jeff

[~^ beancounter ~^]

good one RW, i have been causing a ruckus around
our household w/that one ... 3 kids and all...thanx...


> rw wrote: "What's the name of the world's largest island in a lake on an
> island in a lake?

>> Manitou Lake located on Manitoulin Island located on Lake Huron.

[Wolfgang]

"Jeff Marso" > wrote in message
...
> "Wolfgang" > wrote in
> :
>
>> What I find curious is the assertion that pressure inside the pipe is
>> 0 psi. Why (and how, for that matter) would someone generate and
>> maintain a vacuum in a pipeline at that depth and pressure?
>
> The site says it's PSIG not PSI.
>
> from:
> http://www.unc.edu/~rowlett/units/dictP.html
>
> "psig is a symbol for pound per square inch gauge; this means that the
> pressure has been read from a gauge which actually measures the difference
> between the pressure of the fluid and the pressure of the atmosphere"

Yeah, we've been over this ground. What's your best guess as to the value
of the "pressure of the atmosphere" at a depth of about 6000 ft. below the
surface in the open ocean?

Wolfgang

[~^ beancounter ~^]

isn't each athosphere of water, like 12 lbs...
and it measures, like 6 x 6 feet...or something
like that.....anyway it might be 6,000 / 6 feet x
12 lbs.....12,000 foot lbs (est?).......

[Wolfgang]

"~^ beancounter ~^" > wrote in message
oups.com...
> isn't each athosphere of water, like 12 lbs...
> and it measures, like 6 x 6 feet...or something
> like that.....anyway it might be 6,000 / 6 feet x
> 12 lbs.....12,000 foot lbs (est?).......

Pressure in water increases at the rate of about 3 atmospheres for every one
hundred feet of depth. Thus, at 6000 feet, the pressure is (60 x 3 x ~14.7)
+ ~14.7 pounds per square inch = ~2660.7 psi. The extra ~14.7 is the
pressure exerted by the actual atmosphere. On the page that started all
this, they rounded it up to 2700. Close enough.

Wolfgang

[rw]

Wolfgang wrote:
>
> Yeah, we've been over this ground. What's your best guess as to the value
> of the "pressure of the atmosphere" at a depth of about 6000 ft. below the
> surface in the open ocean?

It's one atmosphere plus whatever correction you need for another 6000
feet of air column.

--
Cut "to the chase" for my email address.

[BJ Conner]

Wolfgang wrote:
> "Jeff Marso" > wrote in message
> ...
> > "Wolfgang" > wrote in
> > :
> >
> >> What I find curious is the assertion that pressure inside the pipe is
> >> 0 psi. Why (and how, for that matter) would someone generate and
> >> maintain a vacuum in a pipeline at that depth and pressure?
> >
> > The site says it's PSIG not PSI.
> >
> > from:
> > http://www.unc.edu/~rowlett/units/dictP.html
> >
> > "psig is a symbol for pound per square inch gauge; this means that the
> > pressure has been read from a gauge which actually measures the difference
> > between the pressure of the fluid and the pressure of the atmosphere"
>
> Yeah, we've been over this ground. What's your best guess as to the value
> of the "pressure of the atmosphere" at a depth of about 6000 ft. below the
> surface in the open ocean?
>
> Wolfgang

Between Mad Cow Disease and CRS I am not sure but I believe I have read
the atmoshperic pressure in one of the gold mines in South Africa was
twice atmoshperic and the mine was 10,00 feet deep. There are some
studys on it relating to nitrogen absorbtion. There recent because
untill recently no one gave a rats ass about any of the miners there.
Life wasn't ( and probably still isn't) great being a miner there.
I am sure somewhere there is a standard atmospheric table that goes
down that far. The Homestake mine in South Dakota is 2 miles deep, you
could take your baraometer on you next visit.
As to the pipeline atmospheric pressure is trivial. Changing the
elevation of the pipe 33 ft is equavalent to one atmosphere.
Differential pressure inside/outside is still about 2,650 PSIG.
I am not sure they use nitrogen in pipelines or not, it would take a
lot of nitrogen. Then again air mixed with a little left over gas can
explode resulting in an expensive repair.
I don't get the oil and gas journal anymore but there was some problems
with metahl hydride or similar compound forming in cold high pressure
gas piplines. Methal hydrieds are the methane crystals that form
naturally in the sea.
The real question is about time. That little slit in the pipe is like
a black hole. Did time change for the crab? Did it take it "forever"
to be digested by the hole. It may not be realtive and time to a crab
may be like time to the pig the cheesehead was holding up to eat the
apples off the tree.

[Wolfgang]

"rw" > wrote in message
m...
> Wolfgang wrote:
>>
>> Yeah, we've been over this ground. What's your best guess as to the
>> value of the "pressure of the atmosphere" at a depth of about 6000 ft.
>> below the surface in the open ocean?
>
> It's one atmosphere plus whatever correction you need for another 6000
> feet of air column.

Really? Why?

Wolfgang
the boy just WILL NOT learn.......that's why he's fun! :)

[~^ beancounter ~^]

it looked pretty quick, to me...it probabally
too the crab a few mnts. to fig. out what
happined......(i'm guessin')...


"The real question is about time. That
little slit in the pipe is like a black hole.
Did time change for the crab? Did it take
it "forever" to be digested by the hole."

[Charlie Choc]

On 24 Oct 2005 10:55:50 -0700, "~^ beancounter ~^" >
wrote:

>isn't each athosphere of water, like 12 lbs...
>and it measures, like 6 x 6 feet...or something
>like that.....anyway it might be 6,000 / 6 feet x
>12 lbs.....12,000 foot lbs (est?).......

The pressure is being measured inside a pipe, presumably connected at both ends
to a point at or above sea level. The pressure of the water outside the pipe (or
an 'atmosphere' of air at that depth) isn't a factor until the pipe is cut.
--
Charlie...
http://www.chocphoto.com

[~^ beancounter ~^]

every 33 ft...so 6,000 / 33 ft = 181.81 @ 14.7 lbs
per sq inch for around = 2,672.607 lbs per sq in
@ 6,000 feet...

-----------------snip------------------------------------
Atmosphere unit of measurement for pressure exerted upon an object or
person. The pressure exerted by the atmosphere at sea level is equal to
the pressure exerted by 33 feet of seawater. Thus, at a depth of 33
feet there is one atmosphere (atm) of water pressure. At 66 feet, there
are two atmospheres of water pressure, etc.

Atmospheric Pressure the pressure exerted by the earth's atmosphere at
any given point at sea level; one atmosphere equals 14.7 pounds per
square inch (psi).

[Wolfgang]

"BJ Conner" > wrote in message
oups.com...
>
> Between Mad Cow Disease and CRS I am not sure but I believe I have read
> the atmoshperic pressure in one of the gold mines in South Africa was
> twice atmoshperic and the mine was 10,00 feet deep. There are some
> studys on it relating to nitrogen absorbtion. There recent because
> untill recently no one gave a rats ass about any of the miners there.
> Life wasn't ( and probably still isn't) great being a miner there.
> I am sure somewhere there is a standard atmospheric table that goes
> down that far. The Homestake mine in South Dakota is 2 miles deep, you
> could take your baraometer on you next visit.

I think I'll pass on the mine visit, but it would be interesting to find out
how quickly atmospheric pressure increases with depth. Even more
interesting is the idea that nitrogen absorption might be a problem. When I
was scuba diving back in the late 60s and early 70s we never concerned
ourselves about it at 2 atmospheres.....with less than an hour of bottom
time, it simply wasn't an issue.

> As to the pipeline atmospheric pressure is trivial.

Agreed. Tell stevie. :)

> Changing the
> elevation of the pipe 33 ft is equavalent to one atmosphere.
> Differential pressure inside/outside is still about 2,650 PSIG.
> I am not sure they use nitrogen in pipelines or not, it would take a
> lot of nitrogen. Then again air mixed with a little left over gas can
> explode resulting in an expensive repair.

Yeah, the potential ignition occurred to me shortly after I asked why they
would use nitrogen. It would indeed take a lot of it to evacuate a pipeline
of any significant length, but nitrogen is pretty cheap....a LOT cheaper
than an explosion, I'd guess.

> I don't get the oil and gas journal anymore but there was some problems
> with metahl hydride or similar compound forming in cold high pressure
> gas piplines. Methal hydrieds are the methane crystals that form
> naturally in the sea.
> The real question is about time. That little slit in the pipe is like
> a black hole. Did time change for the crab? Did it take it "forever"
> to be digested by the hole.

Crabs generally move pretty slowly. Seems to me that insofar as they are
aware of time at all, they'd probably take a fairly leisurely view of it.
Looks to me like the event was probably over before the crab had time to
contemplate it.

> It may not be realtive and time to a crab
> may be like time to the pig the cheesehead was holding up to eat the
> apples off the tree.

Well, we likes our bacon......and very few expend the time or the effort to
ask the pig's opinion. :)

Wolfgang

[BJ Conner]

Wolfgang wrote:
> "BJ Conner" > wrote in message
> oups.com...
> >
> > Between Mad Cow Disease and CRS I am not sure but I believe I have read
> > the atmoshperic pressure in one of the gold mines in South Africa was
> > twice atmoshperic and the mine was 10,00 feet deep. There are some
> > studys on it relating to nitrogen absorbtion. There recent because
> > untill recently no one gave a rats ass about any of the miners there.
> > Life wasn't ( and probably still isn't) great being a miner there.
> > I am sure somewhere there is a standard atmospheric table that goes
> > down that far. The Homestake mine in South Dakota is 2 miles deep, you
> > could take your baraometer on you next visit.
>
> I think I'll pass on the mine visit, but it would be interesting to find out
> how quickly atmospheric pressure increases with depth. Even more
> interesting is the idea that nitrogen absorption might be a problem. When I
> was scuba diving back in the late 60s and early 70s we never concerned
> ourselves about it at 2 atmospheres.....with less than an hour of bottom
> time, it simply wasn't an issue.
>
> > As to the pipeline atmospheric pressure is trivial.
>
> Agreed. Tell stevie. :)
>
> > Changing the
> > elevation of the pipe 33 ft is equavalent to one atmosphere.
> > Differential pressure inside/outside is still about 2,650 PSIG.
> > I am not sure they use nitrogen in pipelines or not, it would take a
> > lot of nitrogen. Then again air mixed with a little left over gas can
> > explode resulting in an expensive repair.
>
> Yeah, the potential ignition occurred to me shortly after I asked why they
> would use nitrogen. It would indeed take a lot of it to evacuate a pipeline
> of any significant length, but nitrogen is pretty cheap....a LOT cheaper
> than an explosion, I'd guess.
>
> > I don't get the oil and gas journal anymore but there was some problems
> > with metahl hydride or similar compound forming in cold high pressure
> > gas piplines. Methal hydrieds are the methane crystals that form
> > naturally in the sea.
> > The real question is about time. That little slit in the pipe is like
> > a black hole. Did time change for the crab? Did it take it "forever"
> > to be digested by the hole.
>
> Crabs generally move pretty slowly. Seems to me that insofar as they are
> aware of time at all, they'd probably take a fairly leisurely view of it.
> Looks to me like the event was probably over before the crab had time to
> contemplate it.
>
> > It may not be realtive and time to a crab
> > may be like time to the pig the cheesehead was holding up to eat the
> > apples off the tree.
>
> Well, we likes our bacon......and very few expend the time or the effort to
> ask the pig's opinion. :)
>
> Wolfgang

This fellow from Illinois is driving thu Winconsin So this guy is
driving down the high and passes an orchard and sees this farmer
holding up a pig so that it can gobble apples right off the tree. The
pig is going crazy eating apples.

"That's the craziet thing I ever saw," the guy tells himself and he
pulls over to the side of the road, gets out of the car, and goes up to
the farmer.

"Hey, I couldn't help noticing what you were doing. Does your pig like
apples?"

The farmer says, "My pig loves apples."

"Well, if you don't mind my saying so, if you took a stick and knocked
the apples on the ground instead of lifting the pig up, you would save
lots of time."

And the farmer answers, "What's time to a pig?"

[Wolfgang]

"BJ Conner" > wrote in message
oups.com...
>
> "What's time to a pig?"

stevie? Can you supply the correct answer?

Wolfgang
who knows the value of primary sources. :)

[BJ Conner]

Jonathan Cook wrote:
> BJ Conner > wrote:
>
> > "What's time to a pig?"
>
> What's the ambient gravity?
When pigs fly??

[Mike Connor]

"Jonathan Cook" > schrieb im Newsbeitrag
...
> BJ Conner > wrote:
>
>> "What's time to a pig?"
>
> What's the ambient gravity?

Presumably zero, as the apples are not falling, otherwise it would not be
necessary to lift the pig.

If apples don´t fall, there is no gravity, just ask Newton.

TL
MC

[rw]

Wolfgang wrote:
>
> stevie? Can you supply the correct answer?

Treasure Island.

--
Cut "to the chase" for my email address.

[Wolfgang]

"rw" > wrote in message
m...
> Wolfgang wrote:
>>
>> stevie? Can you supply the correct answer?
>
> Treasure Island.

Hee, hee, hee.

Wolfgang
ya gotta admire a machine what responds so smooooothly to the slightest
touch of the controls. :)