A U-boat goes beyond crush depth...what happens next?
andrew...@gmail.com
happens when a sub (in this case a Type VII U-Boat) goes beyond its
crush depth.
I realize "crush depth" is somewhat of a spongey term because there's
rated depth vs. the actual precise depth. My question is what happens
to a sub if it's in an uncontrolled sink for whatever reason in a part
of the ocean where the ocean floor is several miles down and it passes
the point where its hull can no longer take the pressure.
Let's say for the purposes of discussion that the real crush depth of a
Type VII U-boat is 300 meters. At that depth, the pressure on the
outside is about 30 atmospheres (450psi). What exactly happens to the
boat as it passes through that depth?
Does the sub inwardly crush on all sides, squishing everyone inside
(sort of like wadding up a ball of aluminum foil)? Or does it crack at
its weakest point and break open? If so, what happens to the sailors
inside? They're thrust out into the ocean at 30 atmospheres...I would
assume that their bodies would quickly be crushed by the water and they
would die nearly instantly from their skulls, ribcages, etc. imploding,
as opposed to drowning over many minutes. (Sorry to be so morbid, but
these things really happened to some WWII sailors on all sides.)
In movies, as the boat sinks near its crush depth, the hull groans and
then bolts start popping, etc. Is that accurate? I'm wondering what
the weakest part of a boat's hull is...the points of entry/exit like
the hatches, torpedo tube doors, etc.?
-Curious Drew, who spent WWII swimming inside his father
Harry Bennett
35g2000cwc.googlegroups.com:
Probably a valve or similar hull fitting will give way causing the water to
start flooding. This will be quite fast given the outside pressure and the
internal pressure being basically atmospheric, ( at the start ) and will
depend upon the size of the hole produced.
This water has two effects; one it makes the submarine heavier causing it
to sink faster and secondly it compresses the air inside the submarine
until the internal pressure matches the outside pressure. At this stage the
internal air space will depend upon the depth of the submarine but it will
be small and basically the crew members will be drowned. Even it the air
space is quite large the crew will die in time from lack of oxygen, cold
and carbon monoxide and carbon dioxide poisoning.
Unless there is a massive failure of the hull, say due to depth charging or
torpedo hit, the crew will be retained inside.
Harry
Mark Bradford
<andrew...@gmail.com> wrote in message
news:1152722100.8...@35g2000cwc.googlegroups.com...
If you are familiar with how a diesel engine works - uses compression rather
than a spark plug to generate the spark. The same principal will apply
when a submarine passes its crush depth and its hull fails. Interestingly,
the crew would be incinerated rather than drown.
As far someone being exposed to water at that depth. The human body is
predominately water. It is the air cavities within the body that would be
affected - the body itself would not be crushed. Think of your sinuses,
gastrointestinal system, lungs, ears, as far as air cavities are concerned.
WaltBJ
discover that the attacked sub, some time after a depth charge attack,
will explode deep down. This is from the Diesel effect mentioned in a
previous answer. Since the sea pressure at 1000 feet down is about 33
times normal atmospheric pressure, half again greater than in ordinary
diesel engines, the air in the sub will very quickly compressed by the
inrushing water - less than a second or so - and jump to the ignition
temperature of just about all the combustible materials inside the sub.
Then explosive combustion ensues with the resulting tremendous
overpressure rupturing the sub's shell and giving the deep-down sound
confirming the sub's destruction. Not a lingering death by any means .
. .
Walt
Christophe Chazot
<andrew...@gmail.com> a écrit dans le message de news:
1152722100.8...@35g2000cwc.googlegroups.com...
First you'll probably have bolts and pipes popping, then if the hull is not
yet filled with water it crushes just as an empty Coca Cola tincan on top of
which you walk. Then the camera stops and there's no use wondering what
happens to the crew.
Best regards by the way,
Christophe Chazot
Fred J. McCall
:Does the sub inwardly crush on all sides, squishing everyone inside
:(sort of like wadding up a ball of aluminum foil)? Or does it crack at
:its weakest point and break open?
In general it will break at the weakest point.
:If so, what happens to the sailors
:inside? They're thrust out into the ocean at 30 atmospheres...
What's supposed to 'thrust them out'. They've got 29 atmospheres of
pressure driving them INTO the boat.
:I would
:assume that their bodies would quickly be crushed by the water and they
:would die nearly instantly from their skulls, ribcages, etc. imploding,
:as opposed to drowning over many minutes. (Sorry to be so morbid, but
:these things really happened to some WWII sailors on all sides.)
In general, I'd think they burn to death. Pressure causes heat. All
the air in the boat is going to VERY rapidly go from 1 atmosphere to
30 atmospheres as water smashes in and compresses the air inside the
boat. They'll also (at the same time) get smashed against bulkheads
Just going down rapidly in pressure (inside a chamber) from an
atmosphere or two overpressure back down to a single atmosphere is
enough to make your break frost and cause humidity to condense on the
walls due to the sudden temperature drop. And that's a very slow
pressure change compared to what you'd get when 30 atmospheres of
pressure comes slamming through the people pipe.
:In movies, as the boat sinks near its crush depth, the hull groans and
:then bolts start popping, etc. Is that accurate?
That happens without hitting crush depth. Changing depth makes
noises.
:I'm wondering what
:the weakest part of a boat's hull is...the points of entry/exit like
:the hatches, torpedo tube doors, etc.?
Anyplace there is a penetration through the pressure hull, which is
why designers try to avoid having any more than are absolutely needed.
--
"Death is my gift." -- Buffy, the Vampire Slayer
george
andrew...@gmail.com wrote:
> I saw Das Boot again not long ago and it made me wonder what actually
> happens when a sub (in this case a Type VII U-Boat) goes beyond its
> crush depth.
Wreath laying ceremonies !
Andy Dingley
>Since the sea pressure at 1000 feet down is about 33
>times normal atmospheric pressure, half again greater than in ordinary
>diesel engines, the air in the sub will very quickly compressed by the
>inrushing water - less than a second or so - and jump to the ignition
>temperature of just about all the combustible materials inside the sub.
This is a fairly rare occurence though - it requires an intact sub to
sink to excess depth, and only then for it rupture. As subs generally
float, then they're most likely to _be_ at this excess depth because the
hull is already breached. A gradual rise in pressure from flooding won't
give you a Diesel effect.
Also a compartment filled with an aerosol of water droplets (quite
likely in a leaking sub) will reduce or prevent the Diesel effect and
any flashover. You still get the sudden increase in pressure, you get
some heat, but much of the excess temperature is reduced by heating of
the water mist instead.
Vince
not to mention that the air volume is reduced by the same fraction as
the pressure increases. Diesel engines require the fuel to be reduced
to very small droplets so that the combustion surface area is large.
Its a fuel air combustion, not a flash over
Vince
Fred J. McCall
Heat is heat. PV=nRT.
--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn
Keith W
"Fred J. McCall" <fmc...@earthlink.net> wrote in message
news:m0nib25cbtu59b7pu...@4ax.com...
> Vince <fir...@firelaw.us> wrote:
> :
> :not to mention that the air volume is reduced by the same fraction as
> :the pressure increases. Diesel engines require the fuel to be reduced
> :to very small droplets so that the combustion surface area is large.
> :Its a fuel air combustion, not a flash over
>
> Heat is heat. PV=nRT.
>
Thats the IDEAL gas law. Its a little more complex when you have
a multiphase fluid.
Keith
Vince
yes but combustion requires ignition. you need sufficient temperature,
not just heat. a hot Hot tub has more heat than a match, but lower
temperature
Vince
Fred J. McCall
:"Fred J. McCall" <fmc...@earthlink.net> wrote in message
Yes, it is. But what it ain't is frigging magic. Compress it that
fast and you're going to get lots of heat.
Fred J. McCall
All of which is rather irrelevant. That 'T' in there is
'temperature', Vinnie...
--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson
Tiger
andrew...@gmail.com at andrew...@gmail.com wrote on 7/12/06 12:35
PM:
Well you could ask the guys on the Thresher if any of these theories are
right or not? You would have to holla, they can't hear you any more......
Needless to say a shitty way to spend ones final moments. Let's leave it at
that.
--
"Live free or die"- The New Hampshire state Moto
Vince
item being ignited. You have to be able to transfer sufficient heat to
raise the temperature of the item you are igniting. very fine droplets
have lots of surface to be exposed to the gas.
Vince
Keith W
> "Keith W" <keith...@kwillshaw.demon.co.uk> wrote:
>
> :"Fred J. McCall" <fmc...@earthlink.net> wrote in message
> :news:m0nib25cbtu59b7pu...@4ax.com...
> :> Vince <fir...@firelaw.us> wrote:
> :> :
> :> :not to mention that the air volume is reduced by the same fraction as
> :> :the pressure increases. Diesel engines require the fuel to be reduced
> :> :to very small droplets so that the combustion surface area is large.
> :> :Its a fuel air combustion, not a flash over
> :>
> :> Heat is heat. PV=nRT.
> :
> :Thats the IDEAL gas law. Its a little more complex when you have
> :a multiphase fluid.
>
> Yes, it is. But what it ain't is frigging magic. Compress it that
> fast and you're going to get lots of heat.
>
And if the water content of the air is high a lot of that heat
gets absorbed changing its state.
Keith
Andy Dingley
wrote:
>All of which is rather irrelevant. That 'T' in there is
>'temperature', Vinnie...
Only if it's a gas (i.e air). Different situation for a mixture of air
and water droplets. Water injection is, after all, a well-known
technique for avoiding premature detonation in internal combustion
engines.
Fred J. McCall
:Fred J. McCall wrote:
:> Vince <fir...@firelaw.us> wrote:
:>
So does your shirt. So does a piece of paper. So do most things,
when it comes down to it.
Ever been in a pressure chamber pressurized to a couple atmospheres
and done a 'crash' decompression to avoid having to do 'stops'? You'd
be surprised how cold it gets.
It works the other way, too.
Vince
nonsense in all three cases, relative to atomized fuel
>
> Ever been in a pressure chamber pressurized to a couple atmospheres
> and done a 'crash' decompression to avoid having to do 'stops'? You'd
> be surprised how cold it gets.
I'm a scuba diver. I know how hot aluminum tanks can get under rapid
compression to 3000 psi. you can stress the metal but they don't ignite.
>
> It works the other way, too.
But not enough to ignite solid material.
Vince
Fred J. McCall
What's the ignition temperature of aluminum, Vinnie? You also don't
fill your tanks in less than a second.
:> It works the other way, too.
:
:But not enough to ignite solid material.
Prove it. Show your work.
Just saying something doesn't make it so. YOU just saying something
makes it automatically questionable.
--
"When you enter a room full of armed men, shoot the first
person who makes a move, hostile or otherwise. He has
started to think and is therefore dangerous..."
-- Colonel Paddy Mayne, co-founder of the SAS
Vince
I presume you mean the auto ignition temperature in air ?
the temperature at whcih if you heat the material it will begin
combusting?
The problem of course is that Ignitability is not a material
characteristic but a product of the form of the material.
Aluminum melts at 660 degrees Celsius, you have to melt it to burn it.
when you heat aluminum you can oxidize the surface.
But when you oxidize the surface of aluminum you get aluminum oxide
which is an excellent refractory material. so solid material is very
hard to burn. powder burns as in thermite, but solid is different.
put an aluminum pot in a gas flame
see what you get
You also don't
> fill your tanks in less than a second.
>
> :> It works the other way, too.
> :
> :But not enough to ignite solid material.
>
> Prove it. Show your work.
>
> Just saying something doesn't make it so. YOU just saying something
> makes it automatically questionable.
80 cu ft air in a standard scuba tank weighs 4 pounds. Scuba tank
weighs 31 pounds. heat transfer in aluminum is excellent. Heat transfer
of air to solid aluminum is slower.
but in any case you have to heat 8 times the mass to 660 degrees c
Assume crush depth for a sub is 1800 feet That is only 60 bar
There isn't enough energy even in theory
Vince
David Phillips
<fmc...@earthlink.net> wrote:
[ snipped the rest of this to get to:]
>Ever been in a pressure chamber pressurized to a couple atmospheres
>and done a 'crash' decompression to avoid having to do 'stops'? You'd
>be surprised how cold it gets.
I call BS.
1. A couple of atmospheres is only 66 feet.
2. If you need to decompress, you need to decompress. Period. There
is NO such thing as a crash decompession. Avoid stops, and you get
bent.
I was a qualified US Navy Deep Sea (HeO2) diving officer. I have been
in pressure chambers for hours at a time. I've gone through surface
decompession (final decompression stop done in a compression chamber
on board ship) for 280 ft ocean dives.
We NEVER did a 'crash decompression'. We NEVER learned of a concept
crash decompression. The concept was NEVER bandied about as any sort
of possibility. You decompress too rapidly, you get DCS.
You're talking through your hat.
It is correct that a pressure chamber does get cooler as its pressure
is reduced, and it gets warmer as its pressure is increased.
BlackBeard
David, in Sub school (70's) we were placed in the chamber and taken
down to 50 ft. with two quick stops (to release guys who couldn't
equalize.) We got very hot and started to sweat. We held at that
pressure briefly (long enough to chant the 11 gen. orders or something
similar) and then were brought up rapidly. No stops on the way back
up, the room filled with a very cold fog as the released air roared out
of the vent, and we stood there at attention, nuts-to-butts, shoulder
to shoulder and shivered. It was part of our escape tank training (and
more than likely part of the psych-eval regarding claustrophobia (sp)).
BB
Vince
As is not unusual there is confusion over language. Decompressing a
chamber is not the same as decompressing a person.
a personal need for "decompression" is based on the time spent at depth.
E.g. breath holding "skin divers" can swim down from the surface to 100
feet and go right back up since they have not absorbed any N2
If scuba divers do a fast descent to 100 feet they can likewise go
straight back up although they have to avoid barometric trauma
If divers spend 30 minutes at 100 feet they have to decompress to allow
the N2 to percolate out of the blood stream
http://www.vanwaasen.de/TABLES/PDIC-SPORT/PDICS-AT.jpg
From a diving perspective you were not in need of decompression
Vince
David Phillips
Ain't that what I said? ;-)
As the chamber was taken to depth, the temperature goes up. As it's
brought to surface pressure, the temp goes down.
You weren't at 50 feet long enough to require decompression. Navy
decompression tables for the time (and possibly still) allowed a 100
minute bottom time for a 50 ft dive. As long as you didn't hold your
breath while the pressure was dropping, you were fine.
I've been in a chamber that was on its way down to 165 ft. for a DCS
treatment. Too bad about equalizing ... it was going down as fast as
it could possibly be driven. That got REALLY hot. Fortunately, the
tank gets vented (kept at pressure, but air let in and out) which gets
things back to normal temps.
Vince
hot of course is a very relative term. A hot tub is 104 degrees F
Coffee at 140 degrees f is on the cold side
Vince
David Phillips
That's certainly true. I don't know what the temp was in the chamber
on its way to 165 ... we were too concerned with keeping equalized on
the way.
Once at depth, I remember it was "oh my god, please vent soon so I
don't freak out" hot.
I much preferred the surface decompression method, where we did 10
minutes of our very long (90 minutes? can't find a 16%02 84%H2 table
online) 40 ft stop, came to the surface, got out of the rig, and did
the full 40 ft stop in the chamber. They took a full minute to
descend to 40 ft, which may have raised the temp some, but not enough
to remark.
Derek Lyons
>On 12 Jul 2006 12:06:29 -0700, "WaltBJ" <walt...@mindspring.com> wrote:
>
>>Since the sea pressure at 1000 feet down is about 33
>>times normal atmospheric pressure, half again greater than in ordinary
>>diesel engines, the air in the sub will very quickly compressed by the
>>inrushing water - less than a second or so - and jump to the ignition
>>temperature of just about all the combustible materials inside the sub.
>
>This is a fairly rare occurence though - it requires an intact sub to
>sink to excess depth, and only then for it rupture. As subs generally
>float, then they're most likely to _be_ at this excess depth because the
>hull is already breached. A gradual rise in pressure from flooding won't
>give you a Diesel effect.
Not entirely true as submarines are not a single open volume. it's
quite possible for say, the Engine Room, to be flooding/flooded enough
to lose depth control - while other compartments retain their
integrity. Those remaining compartments could then be subject to the
Diesel effect.
D.
--
Touch-twice life. Eat. Drink. Laugh.
-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL
BlackBeard
*sigh* Vince, I know that, I certified 26 years ago and still dive.
Nor did I state anything that needed you correction or clarification. I
believe it was an explanation of what Fred was talking about, to David
who was looking from a different side.
BB
WaltBJ
the reports of the deep down explosions heard on the ASW sound gear.
Note that Thresher was discovered to have been reduced to small pieces.
Walt BJ
Fred J. McCall
Precisely, which is why your scuba tank doesn't burst into flame.
Now think about how hot the air in that sub gets when you compress it
in practically no time.
Fred J. McCall
:On Sun, 16 Jul 2006 23:16:17 GMT, Fred J. McCall
:<fmc...@earthlink.net> wrote:
:
:[ snipped the rest of this to get to:]
:
:>Ever been in a pressure chamber pressurized to a couple atmospheres
:>and done a 'crash' decompression to avoid having to do 'stops'? You'd
:>be surprised how cold it gets.
:
:I call BS.
Call and be damned to you.
:1. A couple of atmospheres is only 66 feet.
I didn't measure it, idiot. That's 'couple' as in 'a few'.
:2. If you need to decompress, you need to decompress. Period. There
:is NO such thing as a crash decompession. Avoid stops, and you get
:bent.
The reason for the high speed back 'up' was to avoid being 'down' long
enough to get saturated and have to worry about getting 'bent' with no
stops on the way up. Coming back up fast after compressing meant we
reduced 'bottom time' enough so that we didn't need any stops. If
we'd come up slow we'd have been counted as 'down' long enough to
require a stop.
:I was a qualified US Navy Deep Sea (HeO2) diving officer. I have been
:in pressure chambers for hours at a time. I've gone through surface
:decompession (final decompression stop done in a compression chamber
:on board ship) for 280 ft ocean dives.
:
:We NEVER did a 'crash decompression'. We NEVER learned of a concept
:crash decompression. The concept was NEVER bandied about as any sort
:of possibility. You decompress too rapidly, you get DCS.
Only if you stay down long enough to need the stops, which was the
point of hurrying back to 1 atmosphere.
:You're talking through your hat.
And you're talking out your ass, which is probably appropriate given
that you apparently have your head firmly jammed up it.
Bite me. Then check your dive tables and learn something you should
already know. Whether or not you need decompression stops depends on
how long you are down and how deep you are. The reason for the
'crash' trip back to 1 atmosphere was to avoid having enough time
under enough pressure to require those stops.
:It is correct that a pressure chamber does get cooler as its pressure
:is reduced, and it gets warmer as its pressure is increased.
Mighty big of you to recognize basic laws of physics. A pity you
couldn't engage your brain before acting like an asshat above.
Fred J. McCall
:hot of course is a very relative term. A hot tub is 104 degrees F
:Coffee at 140 degrees f is on the cold side
Until you spill it in your lap.
--
"Oooo, scary! Y'know, there are a lot scarier things
in the world than you ... and I'm one of them."
-- Buffy the vampire
Vince
how do you use water to compress it without the air being surrounded by
water? if the water is doing th compressing it is between the air and
anything solid, so the air cannot ever ignite anything solid. Atomized
fuel is injected into the hot air.
Vince
Peter Skelton
wrote:
This is discussion of a diesel effect in a system with a 60:1
compression ratio and a second or so compression stroke?
There are lots of diesels out there capable of running nicely on
a six to ten second compression stroke and a compression ratio
less than a quarter of that proposed here.
Cooling is, of course an non issue - engines are carefuully
cooled. So is fuel atomization under these conditions.
Grasp firmer straws Vince.
Peter Skelton
Vince
> Vince <fir...@firelaw.us> wrote:
>
> :hot of course is a very relative term. A hot tub is 104 degrees F
> :Coffee at 140 degrees f is on the cold side
>
> Until you spill it in your lap.
>
Which is why the Mcdonalds coffee at 190 degrees F
caused such tissue damage.
Vince
Vince
its not as you call it a diesel effect.
In a diesel engine the air is compressed by solid pistons and cylinders.
The fuel is injected into the hot air. I fully agree that atomized fuel
injected into hot air combusts.
>
> There are lots of diesels out there capable of running nicely on
> a six to ten second compression stroke and a compression ratio
> less than a quarter of that proposed here.
>
> Cooling is, of course an non issue - engines are carefuully
> cooled. So is fuel atomization under these conditions.
>
> Grasp firmer straws Vince.
>
> Peter Skelton
Fred is suggesting igniting solids in a submarine with a "liquid
compression system". The liquid (water under pressure) is between the
air and the fuel. the fuel is solid
It's not going to work
Vince
Peter Skelton
wrote:
nonsense. Oxygen at 12a, temperature in the several hundreds,
paint, paper etc. in contact. The liquid is not between the air
and the fuel.
Peter Skelton
David Phillips
<fmc...@earthlink.net> wrote:
>David Phillips <david.p...@sas.com> wrote:
>
>:On Sun, 16 Jul 2006 23:16:17 GMT, Fred J. McCall
>:<fmc...@earthlink.net> wrote:
>:
>:[ snipped the rest of this to get to:]
>:
>:>Ever been in a pressure chamber pressurized to a couple atmospheres
>:>and done a 'crash' decompression to avoid having to do 'stops'? You'd
>:>be surprised how cold it gets.
>:
>:I call BS.
>
>Call and be damned to you.
>
>:1. A couple of atmospheres is only 66 feet.
>
>I didn't measure it, idiot. That's 'couple' as in 'a few'.
>
>:2. If you need to decompress, you need to decompress. Period. There
>:is NO such thing as a crash decompession. Avoid stops, and you get
>:bent.
>
>The reason for the high speed back 'up' was to avoid being 'down' long
>enough to get saturated and have to worry about getting 'bent' with no
>stops on the way up. Coming back up fast after compressing meant we
>reduced 'bottom time' enough so that we didn't need any stops. If
>we'd come up slow we'd have been counted as 'down' long enough to
>require a stop.
Bzzt. Wrong answer. Total bottom time starts when you leave the
surface, and ends when you start ascending. That's the time that
determines whether you need to decompress. Coming back up quickly
does NOTHING to affect your need for decompression.
In fact, if you're near decompression limits, coming up too quickly
could bring on DCS. An ascent rate of 60 fpm is part of
decompression, even if you don't need to make any stops ( a
no-decompression dive)
Also, you don't know what 'saturated' means with respect to
decompression. If you're saturated, it means that you can continue to
stay at that depth WITHOUT incurring any additional need to
decompress. Your blood has absorbed all the inert gas that it can.
>
>:I was a qualified US Navy Deep Sea (HeO2) diving officer. I have been
>:in pressure chambers for hours at a time. I've gone through surface
>:decompession (final decompression stop done in a compression chamber
>:on board ship) for 280 ft ocean dives.
>:
>:We NEVER did a 'crash decompression'. We NEVER learned of a concept
>:crash decompression. The concept was NEVER bandied about as any sort
>:of possibility. You decompress too rapidly, you get DCS.
>
>Only if you stay down long enough to need the stops, which was the
>point of hurrying back to 1 atmosphere.
As I wrote above, hurrying back up does nothing. A rapid ascent does
nothing to reduce the need for decompression.
>
>:You're talking through your hat.
>
>And you're talking out your ass, which is probably appropriate given
>that you apparently have your head firmly jammed up it.
>
>Bite me. Then check your dive tables and learn something you should
>already know. Whether or not you need decompression stops depends on
>how long you are down and how deep you are. The reason for the
>'crash' trip back to 1 atmosphere was to avoid having enough time
>under enough pressure to require those stops.
Check your dive manuals yourself. You are incorrect. There is no
valid 'crash ascent' protocol. Ascent time is not part of bottom
time, and does nothing to reduce required decompression time.
You know not whereof you speak.
>
>:It is correct that a pressure chamber does get cooler as its pressure
>:is reduced, and it gets warmer as its pressure is increased.
>
>Mighty big of you to recognize basic laws of physics. A pity you
>couldn't engage your brain before acting like an asshat above.
Hmm. Find me a US Navy, PADI, or NAUI dive manual that shows a crash
ascent, and I'll apologize.
Here's a hint. Google for 'decompression tables'. Click on the link
'Basic Decompression Table Concepts and Use' at
www.brooks.af.mil/web/hyper/Basic_Deco.pdf
Read page 10.
Vince
we are talking about a submarine open to the sea. The water is spraying
everywhere. it reflects form every surface. We pre wet combustible
surfaces all the time to prevent combustion. not to mention the water
droplets soaking up the heat just as fast as the air compresses.
Vince
Mark Bradford
"Vince" <fir...@firelaw.us> wrote in message
news:PJSdnQhadeunrSDZ...@comcast.com...
to a sub when it exceeds its crush depth. I am taking for granted that this
will only happen under a classified number of feet/meters of water, at which
time, the delta in pressure inside the sub will be virtually instantaneous
because of the equalization between the outside and inside of the sub.
The assumptions for the above are that there are still spaces in the sub
where there is air and the hull breach is massive. Somebody please correct
me if I am wrong.
Mark
>
Vince
AFAIR from lectures at David Taylor some years ago, the assumption is
that a pressure crack starts and propagates. water under high pressure
sprays into the compartment. It "sprays" rather than "floods" because
the pressure induced velocity is greater than velocity generated by
gravity. Failure is then progressive from compartment to compartment
since the sub now descends at greater speed.
FWIW according to GARZEKE the same phenomenon occurred with The Titanic
albeit at shallower depths
Vince
Peter Skelton
wrote:
No we aren't. It starts with a leak (which propogates) and one
compartment fills. When the pressure rises enough catastrophic
and sudden failure of a bulkhead results. The diesel thing
follows in the space behind the bulkhead.
Peter Skelton
Vince
its still "open to the sea" the bulkhead fails the same way the hull
fails. it splits and the pressure sprays in. water is everywhere
Vince
Derek Lyons
>All the foregoing rationalizing is interesting but not one discussed
>the reports of the deep down explosions heard on the ASW sound gear.
Implosions and explosions will sound much the same - therefore, this
is neutral evidence at best.
>Note that Thresher was discovered to have been reduced to small pieces.
I still wonder about that - as the condition of Thresher's remains has
only been discussed obliquely.
Errol Cavit
> Peter Skelton wrote:
>> On Tue, 18 Jul 2006 15:02:18 -0400, Vince <fir...@firelaw.us>
>> wrote:
>>
>>> Peter Skelton wrote:
>>>> On Tue, 18 Jul 2006 10:07:28 -0400, Vince <fir...@firelaw.us>
>>>> wrote:
>>>>
>>>>> Peter Skelton wrote:
>>>>>> On Tue, 18 Jul 2006 07:22:31 -0400, Vince <fir...@firelaw.us>
>>>>>> wrote:
>>>>>>
>>>>>>> Fred J. McCall wrote:
>>>>>>>> Vince <fir...@firelaw.us> wrote:
>>>>>>>>
>>>>>>>> :Fred J. McCall wrote:
>>>>>>>> :> Vince <fir...@firelaw.us> wrote:
>>>>>>>> :> :> :Fred J. McCall wrote:
>>>>>>>> :> :> Vince <fir...@firelaw.us> wrote:
>>>>>>>> :> :> :> :> :Fred J. McCall wrote:
>>>>>>>> :> :> :> Vince <fir...@firelaw.us> wrote:
>>>>>>>> :> :> :> :> :> :> :Fred J. McCall wrote:
>>>>>>>> :> :> :> :> Vince <fir...@firelaw.us> wrote:
>>>>>>>> :> :> :> :> :> :> :> :> :Andy Dingley wrote:
>>>>>>>> :> :> :> :> :> On 12 Jul 2006 12:06:29 -0700, "WaltBJ"
>>>>>>>> <walt...@mindspring.com> wrote:
>>>>>>>> :> :> :> :> :>
<snip, leaving evidence of silly number of quotes>
Trim, you rude, lazy jerks. Some of us still hope to find some useful
information in this thread, and you arent making it any easier.
--
Errol Cavit | errol...@hotmail.com
Il vino è la luce del sole catturata dall'acqua."
(Wine is sunlight held together by water.)
Attributed to Galileo Galilei
Fred J. McCall
Quite simply. Do I really need to draw you a picture of something
this simple?
:if the water is doing th compressing it is between the air and
:anything solid, ...
Nope. Do you think they just remove the hull and leave an air bubble,
or what.
Vinnie, a weak point in the hull gives way. The hull is full of AIR.
The water coming in the hole is pretty much like a solid at those
pressure differentials. It doesn't run in in little sprays and
driblets like in the movies. You get a solid bar of water smashing
down through the middle of the people pipe just like a piston in a
diesel engine.
Vince
> :
> :how do you use water to compress it without the air being surrounded by
> :water?
>
> Quite simply. Do I really need to draw you a picture of something
> this simple?
>
> :if the water is doing th compressing it is between the air and
> :anything solid, ...
>
> Nope. Do you think they just remove the hull and leave an air bubble,
> or what.
>
> Vinnie, a weak point in the hull gives way. The hull is full of AIR.
> The water coming in the hole is pretty much like a solid at those
> pressure differentials. It doesn't run in in little sprays and
> driblets like in the movies. You get a solid bar of water smashing
> down through the middle of the people pipe just like a piston in a
> diesel engine.
nonsense. We generate high pressure water all the time. 800-1000 psi
is typical for water mist systems. Well within the depth we are describing
When you split the hull its a crack, not a pipe.
Nothing channels the water into a stream
Water under high pressure forced through a crack sprays wildly in all
directions.
But any that that goes across the compartment as a sold bar hits an
object that acts as a deflector. My students shoot solid streams of
water at deflectors all the time. The deflector breaks the water into
droplets Thats how sprinkler systems work.
Vince
Peter Skelton
wrote:
Sorry Vince, but that is absolute nonsense. The interior
bulkheads have nothing like the hull's strength, their failure is
much faster.
Peter Skelton
Vince
I said the same way. not at the same speed
They still fail the same way by "tearing"
when the metal tears a high speed turbulent jet of water spurts throguh
the crack
(although parenthetically I'm not sure your statement is correct about
submarines. IIRC at least from diesel boats the subdivision of the
pressure hull had the same rating as the hull itself.
Vince
Fred J. McCall
It caused such tissue damage because it was at 140 degrees?
Context, Vinnie - get some.
Fred J. McCall
:Fred is suggesting igniting solids in a submarine with a "liquid
:compression system".
No, Vinnie, I'm just suggesting that your arguments are so weak as to
be nonexistent.
:The liquid (water under pressure) is between the
:air and the fuel.
Oh? How'd that happen?
Peter Skelton
wrote:
You remember incorrectly about British and German boats (except
for some early models), I don't know about American.
As far as the main argument goes, speed of collapse is the
important factor, it affects atomization, time available for
wetting and rate of pressure/temperature rise. You are arguing
that it is the same except for everything that matters.
Peter Skelton
Fred J. McCall
:Peter Skelton wrote:
:> On Tue, 18 Jul 2006 10:07:28 -0400, Vince <fir...@firelaw.us>
Yes, we are, and water at 30 atmospheres of pressure doesn't 'spray'.
It's essentially a solid piston of water ramming straight down that
cylinder euphemistically known as 'the people pipe'. There is no
'pre-wetting'. There's just a big 'wham' as things collapse.
You've been watching too many movies. Submarines below crush depth
don't fail in little squirts and driblets, with water spraying out and
guys trying to stop it. The first hull failure happens and from then
on out it's pretty much all one swell foop over a very short period of
time.
--
"Rule Number One for Slayers - Don't die."
-- Buffy, the Vampire Slayer
Vince
> Vince <fir...@firelaw.us> wrote:
>
> :Fred J. McCall wrote:
> :> Vince <fir...@firelaw.us> wrote:
> :>
> :> :hot of course is a very relative term. A hot tub is 104 degrees F
> :> :Coffee at 140 degrees f is on the cold side
> :>
> :> Until you spill it in your lap.
> :
> :Which is why the Mcdonalds coffee at 190 degrees F
> :caused such tissue damage.
>
> It caused such tissue damage because it was at 140 degrees?
>
> Context, Vinnie - get some.
>
140 coffee is hot in your lap 190 coffee causes full thickness burns
Vince
> Vince <fir...@firelaw.us> wrote:
>
> :Fred is suggesting igniting solids in a submarine with a "liquid
> :compression system".
>
> No, Vinnie, I'm just suggesting that your arguments are so weak as to
> be nonexistent.
>
> :The liquid (water under pressure) is between the
> :air and the fuel.
>
> Oh? How'd that happen?
>
not a piston. the air is not a single homogeneous mass, it's full of
water in droplets of various sizes.
Vince
Vince
you are incorrect. the shape of the orifice for the high pressure
stream determines what happens to the water.
> It's essentially a solid piston of water ramming straight down that
> cylinder euphemistically known as 'the people pipe'. There is no
> 'pre-wetting'. There's just a big 'wham' as things collapse.
>
> You've been watching too many movies. Submarines below crush depth
> don't fail in little squirts and driblets, with water spraying out and
> guys trying to stop it. The first hull failure happens and from then
> on out it's pretty much all one swell foop over a very short period of
> time.
Actually you have not watched enough high pressure water lines water
under high pressure keeps moving and it bounces
I agree the entire process is over in seconds, far too little time to
ignite anything.
Vince
Vince
Vince
A difference is a difference only if it makes a difference.
none of this makes any difference to the supposed ignition of solid
material by compression heated air. Ignition is a process that is
dependent on on heat and vaporization. Only vapors burn
"Ease of ignition of a solid material is therefore dependent on the ease
with which its surface temperature can be raised to the firepoint, e.g.,
by exposure to radiant heat or to a flow of hot gases. This is less
dependent on the chemistry of the decomposition process than on the
thickness and physical properties of the solid, namely, its thermal
conductivity (k), density (r) and heat capacity (c). Thin solids, such
as wood shavings (and all thin sections), can be ignited very easily
because they have a low thermal mass, that is, relatively little heat is
required to raise the temperature to the firepoint. However, when heat
is transferred to the surface of a thick solid, some will be conducted
from the surface into the body of the solid, thus moderating the
temperature rise of the surface. It can be shown theoretically that the
rate of rise of the surface temperature is determined by the thermal
inertia of the material, that is, the product krc. This is borne out in
practice, since thick materials with a high thermal inertia (e.g., oak,
solid polyurethane) will take a long time to ignite under a given heat
flux, whereas under identical conditions thick materials with a low
thermal inertia (e.g., fibre insulating board, polyurethane foam) will
ignite quickly (Drysdale 1985).
http://www.ilo.org/encyclopedia/?doc&nd=857100190&nh=0&ssect=1
take a heat gun, the kind you strip paint with. See how long it takes
to ignite a single sheet of paper
Sheesh
Vince
Peter Skelton
wrote:
With PO2 at 12?
Sheesh yourself.
Peter Skelton
Fred J. McCall
:Peter Skelton wrote:
:>
:> No we aren't. It starts with a leak (which propogates) and one
:> compartment fills. When the pressure rises enough catastrophic
:> and sudden failure of a bulkhead results. The diesel thing
:> follows in the space behind the bulkhead.
:
:its still "open to the sea" the bulkhead fails the same way the hull
:fails. it splits and the pressure sprays in. water is everywhere
Water with 30+ atmospheres pressure behind it doesn't 'spray', Vinnie.
--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson
Vince
> Vince <fir...@firelaw.us> wrote:
>
> :Peter Skelton wrote:
> :>
> :> No we aren't. It starts with a leak (which propogates) and one
> :> compartment fills. When the pressure rises enough catastrophic
> :> and sudden failure of a bulkhead results. The diesel thing
> :> follows in the space behind the bulkhead.
> :
> :its still "open to the sea" the bulkhead fails the same way the hull
> :fails. it splits and the pressure sprays in. water is everywhere
>
> Water with 30+ atmospheres pressure behind it doesn't 'spray', Vinnie.
>
yes it does. you are only talking 450 psi.
We have to build special nozzles to keep it from spraying
but as soon as it his anything it forms flat sheets and droplets
Vince
Fred J. McCall
I'll note that this is different than what you initially said.
It's hardly 'full', Vinnie. There's just not that kind of time.
Fred J. McCall
:Fred J. McCall wrote:
:> Vince <fir...@firelaw.us> wrote:
:>
You are incorrect. We're talking about a submarine hull failing at
depth. There is no 'orifice' involved, except for the one which you
seem to be keeping your head in.
:> It's essentially a solid piston of water ramming straight down that
:> cylinder euphemistically known as 'the people pipe'. There is no
:> 'pre-wetting'. There's just a big 'wham' as things collapse.
:>
:> You've been watching too many movies. Submarines below crush depth
:> don't fail in little squirts and driblets, with water spraying out and
:> guys trying to stop it. The first hull failure happens and from then
:> on out it's pretty much all one swell foop over a very short period of
:> time.
:
:Actually you have not watched enough high pressure water lines water
:under high pressure keeps moving and it bounces
Actually, you haven't a clue what I have and have not done. Get back
to me when you've been through DC school. I'd suggest a few classes.
I've both patched pipes and sealed hull breeches under an order of
magnitude less pressure than we're talking about here, and it ranges
somewhere between difficult and impossible to do. With a 30+
atmosphere pressure differential you wouldn't even have time to know
you were dead.
:I agree the entire process is over in seconds, far too little time to
:ignite anything.
It certainly wouldn't stay lit long, in any case.
Fred J. McCall
:Fred J. McCall wrote:
:> Vince <fir...@firelaw.us> wrote:
:>
:> :Peter Skelton wrote:
:> :>
:> :> No we aren't. It starts with a leak (which propogates) and one
:> :> compartment fills. When the pressure rises enough catastrophic
:> :> and sudden failure of a bulkhead results. The diesel thing
:> :> follows in the space behind the bulkhead.
:> :
:> :its still "open to the sea" the bulkhead fails the same way the hull
:> :fails. it splits and the pressure sprays in. water is everywhere
:>
:> Water with 30+ atmospheres pressure behind it doesn't 'spray', Vinnie.
:>
:
:yes it does. you are only talking 450 psi.
'Only' 450 PSI? I'll tell you what. Let me use a standard Navy fire
hose with less than 1/3 that much pressure (and a few people to help
me hold it) and spray it at you. It'll be a good lesson in what even
relatively low water pressure can do.
:We have to build special nozzles to keep it from spraying
:but as soon as it his anything it forms flat sheets and droplets
Gee, if it's so trivial why would a pressure hull fail?
Mark Bradford
"Fred J. McCall" <fmc...@earthlink.net> wrote in message
news:bt4ub2hph66qhdl6j...@4ax.com...
How long does a spark stay lit in a diesel cylinder? Fred and Peter are
right on this one - the sudden delta in pressure would turn the interior of
the sub into a giant diesel cylinder and with no exhaust valves, the hull
would explode because it is designed to keep pressure out not in. Death to
the crew would be faster than instantaneous.
Mark
David Phillips
<fmc...@earthlink.net> wrote:
>Vince <fir...@firelaw.us> wrote:
>
>:Peter Skelton wrote:
>:>
>:> No we aren't. It starts with a leak (which propogates) and one
>:> compartment fills. When the pressure rises enough catastrophic
>:> and sudden failure of a bulkhead results. The diesel thing
>:> follows in the space behind the bulkhead.
>:
>:its still "open to the sea" the bulkhead fails the same way the hull
>:fails. it splits and the pressure sprays in. water is everywhere
>
>Water with 30+ atmospheres pressure behind it doesn't 'spray', Vinnie.
Really? I'm looking at a Coleman Powermate pressure washer that
delivers a spray of water at 238 ATM (3500 PSI).
Vince
> Vince <fir...@firelaw.us> wrote:
>
> :Fred J. McCall wrote:
> :> Vince <fir...@firelaw.us> wrote:
> :>
> :> :Fred is suggesting igniting solids in a submarine with a "liquid
> :> :compression system".
> :>
> :> No, Vinnie, I'm just suggesting that your arguments are so weak as to
> :> be nonexistent.
> :>
> :> :The liquid (water under pressure) is between the
> :> :air and the fuel.
> :>
> :> Oh? How'd that happen?
> :
> :how are you "compressing" the air. with water in the compartment. its
> :not a piston. the air is not a single homogeneous mass, it's full of
> :water in droplets of various sizes.
>
> I'll note that this is different than what you initially said.
>
> It's hardly 'full', Vinnie. There's just not that kind of time.
>
lets have a compartment
if you are "compressing" the air in the compartment compression is
directly related to the volume of water that enters.
the water enters under high pressure e.g. 45psi. it crosses the
compartment and hits steel at high pressure. When a stream of water hits
steel it "fractures". (we photograph this all the time). each fractured
stream continues to hit other steel, The pressure is also lower in the
compartment so some of the high pressure water flashes to vapor.
The droplets and vapor "fill" the compartment the kinetic energy
overcomes gravity The air is being compressed by the water. but its a
giant foaming mass
Vince
Vince
We teach and do research on high pressure water mist systems for the navy
Vince
Vince
Fire hoses have nozzles. they are designed to create a stream.
if you hit flat steel with a stream of any shape you get droplets.
Firefighter have known for years that droplets are more efficient.
it is routine in fighting engine compartment fires to aim the stream at
the bulkhead to get the droplets. teh higher the pressure, teh smaller
the droplets.
Vince
Vince
no one is talking about the crew. It isn't a diesel cylinder. sparks
don't ignite solids. the pressure is in the form of water in droplets
(billions of them) its over in a fraction of a second. there is no
time to ignite solids which requires vaporization or pyrolosys and
involves thermal inertia
Vince
Vince
Vince
not to mention
what happens if you hit flat steel with a solid stream?
little droplets everywhere
Vince
Fred J. McCall
:On Thu, 20 Jul 2006 00:55:12 GMT, Fred J. McCall
Gee, so why would submarine hulls ever collapse? Surely they're
stronger than your pressure washer!
Fred J. McCall
:lets have a compartment
:
:if you are "compressing" the air in the compartment compression is
:directly related to the volume of water that enters.
:
:the water enters under high pressure e.g. 45psi. it crosses the
:compartment and hits steel at high pressure. When a stream of water hits
:steel it "fractures". (we photograph this all the time). each fractured
:stream continues to hit other steel, The pressure is also lower in the
:compartment so some of the high pressure water flashes to vapor.
:
:The droplets and vapor "fill" the compartment the kinetic energy
:overcomes gravity The air is being compressed by the water. but its a
:giant foaming mass
I don't know a lot of subs with a crush depth of only a hundred feet
or so, Vinnie. We're not talking about half a century ago...
David Phillips
>>
>
>Fire hoses have nozzles. they are designed to create a stream.
>
>if you hit flat steel with a stream of any shape you get droplets.
>
>Firefighter have known for years that droplets are more efficient.
>it is routine in fighting engine compartment fires to aim the stream at
>the bulkhead to get the droplets. teh higher the pressure, teh smaller
>the droplets.
Vince, can I hemi-semi-demi disagree with you on this one? Mostly on
fine detail.
I haven't been a firefighter in years, and I've been out of the Navy
for almost 25 years, but even back then our nozzles didn't produce a
solid stream. Our adjustable nozzles, which could produce a wide
spray, had an aerated stream when set to the stream setting. It
definitely had droplets in it, just real close together, and probably
bigger ones than when we had the nozzle adjusted to a wider spray.
I know I don't have the correct terms here, but the 'stream' setting
was more like the output from a nozzle on a garden hose than it was
like the output from a hoze with no nozzle. Kind of like the
difference between an aerated sink faucet, and one without.
When we were fighting fires, we'd use a medium wide spray when we were
trying to cool down things, and get them wet, and we'd go to the
'solid' stream when we were trying to break apart the burning
material.
In Navy firefighting, we'd also usually have a second hose above us
with a 'pineapple' nozzle, spraying a nice wide spray just over us to
help cool and wet things down.
Of course, if your nozzle isn't adjustable, you could get more 'spray'
by bouncing off a solid object, even if your nozzle was aerated, just
as you say.
Fred J. McCall
Which has bugger all to do with the topic to hand.
I'd suggest a few courses, Vinnie.
Fred J. McCall
:Fred J. McCall wrote:
:> Vince <fir...@firelaw.us> wrote:
:>
:> :Fred J. McCall wrote:
:> :> Vince <fir...@firelaw.us> wrote:
:> :>
:> :> :Peter Skelton wrote:
:> :> :>
:> :> :> No we aren't. It starts with a leak (which propogates) and one
:> :> :> compartment fills. When the pressure rises enough catastrophic
:> :> :> and sudden failure of a bulkhead results. The diesel thing
:> :> :> follows in the space behind the bulkhead.
:> :> :
:> :> :its still "open to the sea" the bulkhead fails the same way the hull
:> :> :fails. it splits and the pressure sprays in. water is everywhere
:> :>
:> :> Water with 30+ atmospheres pressure behind it doesn't 'spray', Vinnie.
:> :>
:> :
:> :yes it does. you are only talking 450 psi.
:>
:> 'Only' 450 PSI? I'll tell you what. Let me use a standard Navy fire
:> hose with less than 1/3 that much pressure (and a few people to help
:> me hold it) and spray it at you. It'll be a good lesson in what even
:> relatively low water pressure can do.
:>
:> :We have to build special nozzles to keep it from spraying
:> :but as soon as it his anything it forms flat sheets and droplets
:>
:> Gee, if it's so trivial why would a pressure hull fail?
:
:Fire hoses have nozzles. they are designed to create a stream.
:
:if you hit flat steel with a stream of any shape you get droplets.
Which is rather the issue. You don't get a 'stream' when the hull
fails, Vinnie. There are lots of droplets in the ocean. You just
can't see them because they're surrounded by water!
:Firefighter have known for years that droplets are more efficient.
:it is routine in fighting engine compartment fires to aim the stream at
:the bulkhead to get the droplets. teh higher the pressure, teh smaller
:the droplets.
All very nice, but answer the question.
If it's so trivial, why would a pressure hull fail?
Vince
OFCS Scuba tanks hold 3500 psi. you can build a hull as thick as you
want. the Titanic is at 12,000 FSW.
We just don't build subs that thick since it doesn't make sense.
(as you well know
sheesh
Vince
Vince
Let me be clear
an "adjustable" fire nozzle will never produce a true stream It has a
device in the stream that interacts with a cone.
True "stream" nozzles have no such device and can often be fitted with
interchangeable tips
e.g
http://www.croker.com/9-6%20Nozz.%20for%20Monitors%209046.pdf
Basically you always want the most droplets possible of the size and
velocity you need Fog nozzles if you are up close
and stream nozzles if you are far away
Vince
Vince
but the principle is the same.
it just works faster at 450 psi
Vince
Mark Bradford
"Vince" <fir...@firelaw.us> wrote in message
news:IJ-dnVLPC4W_PiLZ...@comcast.com...
exhaust valve or some reasonable facsimile thereof? If there is not, a
strange thing called compression occurs because there is nowhere for the air
to go. Please explain what happens then. Show all work.
Mark
>
> Vince
David Phillips
>David Phillips wrote:
>> Vince, can I hemi-semi-demi disagree with you on this one? Mostly on
>> fine detail.
>>
>> I haven't been a firefighter in years, and I've been out of the Navy
>> for almost 25 years, but even back then our nozzles didn't produce a
>> solid stream. Our adjustable nozzles, which could produce a wide
>> spray, had an aerated stream when set to the stream setting. It
>> definitely had droplets in it, just real close together, and probably
>> bigger ones than when we had the nozzle adjusted to a wider spray.
>>
>> I know I don't have the correct terms here, but the 'stream' setting
>> was more like the output from a nozzle on a garden hose than it was
>> like the output from a hoze with no nozzle. Kind of like the
>> difference between an aerated sink faucet, and one without.
>
>Let me be clear
>
>an "adjustable" fire nozzle will never produce a true stream It has a
>device in the stream that interacts with a cone.
>
>True "stream" nozzles have no such device and can often be fitted with
>interchangeable tips
>e.g
>http://www.croker.com/9-6%20Nozz.%20for%20Monitors%209046.pdf
>
>Basically you always want the most droplets possible of the size and
>velocity you need Fog nozzles if you are up close
>and stream nozzles if you are far away
Thanks, Vince. I've switched the subject line as we're completely off
the crush depth discussion now.
We had adjustable nozzles to put on hoses, and I think we had a stream
nozzle on a monitor on top of the truck.
I think though (and this is a LOOOOONG time ago) that our newer truck
had an aerated nozzle on its monitor. I can't remember at all whether
it was adjustable (doesn't make a great deal of sense to me, for a
mounted nozzle to have a spray setting)
Am I right in guessing that a solid stream nozzle will have greater
range than an aerated nozzle of equal diameter and pressure?
Also, it seems like most nozzles on the end of the modern ladder or
boom truck are at least an aerating nozzle, rather than a solid
stream. That observation isn't based upon up close inspection,
though, so I can't be certain.
If the previous guess about solid stream vs. aerated stream is
correct, is the thinking that the tradeoff of having the extra cooling
effect of the droplets in the aerated stream is worth the loss in
distance?
Thanks,
Paul J. Adam
<mark...@bellsouth.net> writes
>When a compartment in a sub floods, where does the air go? Is there an
>exhaust valve or some reasonable facsimile thereof? If there is not, a
>strange thing called compression occurs because there is nowhere for the air
>to go. Please explain what happens then. Show all work.
Dusting off some extremely rusty thermodynamics...
Going for best case with an adiabatic compression, collapse occurring
around 1000m so a compression of 100 to 1, assuming air as an ideal gas,
starting temperature 293 Kelvin. Temperature * (volume ^ [gamma-1])
remains constant; for air, gamma (the ratio of specific heats) is 1.4
So, 293 * (100 ^ 0.4) = T2 * (1 ^ 0.4)
which gets us a final air temperature of 1848 Kelvin, or 1575 degrees
Celsius, or 2,900 Stone Age, assuming my calculations are correct.
Now, at first glance that's very hot - above the melting point of steel,
for example.
However, this hits two snags. The first is that it assumes zero losses
or cooling for any cause; it's the highest temperature that an ideal
compression would allow. Reality inevitably falls short.
The second, is that hot air is just, well, hot air: this air temperature
is around that found in the flame from a gas hob, for example, and it
takes time to get solid matter to begin burning even held in such a
flame. In the conditions of a collapsing submarine - which might
charitably be called "confused", even "turbulent" - this compressed air
will not be forming a neat, insulated pocket centred on the most
combustible object inside the hull, but will be divided, moving, and
vigorously attempting to find a path upwards and outwards while being
stirred by the chaotic flows of the water. The faster the initial
compression, the greater the turbulence, spray and flow.
--
Paul J. Adam
scott s.
news:yaoGMrZK...@jrwlynch.demon.co.uk:
> In message <fxOvg.15662$ZH1....@bignews4.bellsouth.net>, Mark
> Bradford <mark...@bellsouth.net> writes
>>When a compartment in a sub floods, where does the air go? Is there
>>an exhaust valve or some reasonable facsimile thereof? If there is
>>not, a strange thing called compression occurs because there is
>>nowhere for the air to go. Please explain what happens then. Show
>>all work.
>
> Dusting off some extremely rusty thermodynamics...
>
> Going for best case with an adiabatic compression, collapse occurring
> around 1000m so a compression of 100 to 1, assuming air as an ideal
> gas, starting temperature 293 Kelvin. Temperature * (volume ^
> [gamma-1]) remains constant; for air, gamma (the ratio of specific
> heats) is 1.4
>
> So, 293 * (100 ^ 0.4) = T2 * (1 ^ 0.4)
>
> which gets us a final air temperature of 1848 Kelvin, or 1575 degrees
> Celsius, or 2,900 Stone Age, assuming my calculations are correct.
It seems to me that thermodynamic considerations are not
sufficient. I think the fluid dynamics must also be accounted
for. I find Vince's arguments more convincing. Also, treating
the interior as an ideal gas might show the limiting or boundary
case, but might not be valid in the probable case.
scott s.
.
Paul J. Adam
<75270...@csi.xcom> writes
>>
>> which gets us a final air temperature of 1848 Kelvin, or 1575 degrees
>> Celsius, or 2,900 Stone Age, assuming my calculations are correct.
>It seems to me that thermodynamic considerations are not
>sufficient.
Enough to persuade me we're not going to see any explosions.
>I think the fluid dynamics must also be accounted
>for.
There's the question of getting this energy from the air into
"something" sufficiently volatile that it'll burn in the available time,
before the inrush of cold water arrives and ends all the potential
pyromania. Warships tend to avoid leaving quantities of volatile
flammables around and exposed.
> Also, treating
>the interior as an ideal gas might show the limiting or boundary
>case, but might not be valid in the probable case.
It shows the upper limit for the air temperature, is all.
Think of waving a gas flame over an object for a second or two, before
immediately turning a hose on it.
--
Paul J. Adam
george
Vince wrote:
> not to mention
> what happens if you hit flat steel with a solid stream?
>
> little droplets everywhere
>
No.
We have this little gadget that, with saphire and highly pressurised
water, cuts steel just like a knife through butter...
Paul J. Adam
george <gbl...@hnpl.net> writes
Try it without the sapphire. It'll be as effective as trying to cut or
grind steel with a flimsy resin honeycomb: the grits are the cutting
agent, not the water.
--
Paul J. Adam
Vince
ever open a soda bottle?
Where did all that gas come from?
either it vents or it dissolves into the water
it compresses along the way
Vince
,
Vince
> Also, it seems like most nozzles on the end of the modern ladder or
> boom truck are at least an aerating nozzle, rather than a solid
> stream. That observation isn't based upon up close inspection,
> though, so I can't be certain.
>
> If the previous guess about solid stream vs. aerated stream is
> correct, is the thinking that the tradeoff of having the extra cooling
> effect of the droplets in the aerated stream is worth the loss in
> distance?
also correct.
solid streams are of very limited utility
Vince
Vince
not at the pressures we are describing and not at the distances
Vince
Vince
Actually not. you can cut steel with water with extremely high
pressure. the sapphire is the nozzle, but the steel has to be very clsoe
to the nozzle
Vince
Mark Bradford
"Paul J. Adam" <ne...@jrwlynch.demon.co.uk> wrote in message
news:yaoGMrZK...@jrwlynch.demon.co.uk...
Paul, thank you for that response - I learned a lot from that. My next
question is what happens to the compressed air that is trapped inside the
hull of the submarine. I mean how much internal pressure can a hull
contain? My assumption is that it is less than the external pressure that
it can keep out.
Mark
Vince
you claimed it was a liquid piston.
> :Firefighter have known for years that droplets are more efficient.
> :it is routine in fighting engine compartment fires to aim the stream at
> :the bulkhead to get the droplets. teh higher the pressure, teh smaller
> :the droplets.
>
> All very nice, but answer the question.
>
> If it's so trivial, why would a pressure hull fail?
Because it makes no sense to build them strong enough to not fail
Vince
Derek Lyons
>Paul, thank you for that response - I learned a lot from that. My next
>question is what happens to the compressed air that is trapped inside the
>hull of the submarine.
Nothing.
Keep in mind the air is compressed to the pressure of the ocean.
>I mean how much internal pressure can a hull contain? My assumption is that
>it is less than the external pressure that it can keep out.
If the hull is breached, and the air inside thus compressed to the
pressure of the ocean - the net force on the hull is zero. The forces
balance.
D.
--
Touch-twice life. Eat. Drink. Laugh.
-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL
Fred J. McCall
Vinnie is still thinking of a stream in air. That's not what happens
at crush depth.
Think 'solid wall of water', Vinnie...
Fred J. McCall
:Fred J. McCall wrote:
:> David Phillips <david.p...@sas.com> wrote:
:>
:> :On Thu, 20 Jul 2006 00:55:12 GMT, Fred J. McCall
:> :<fmc...@earthlink.net> wrote:
:> :
:> :>Vince <fir...@firelaw.us> wrote:
:> :>
:> :>:Peter Skelton wrote:
:> :>:>
:> :>:> No we aren't. It starts with a leak (which propogates) and one
:> :>:> compartment fills. When the pressure rises enough catastrophic
:> :>:> and sudden failure of a bulkhead results. The diesel thing
:> :>:> follows in the space behind the bulkhead.
:> :>:
:> :>:its still "open to the sea" the bulkhead fails the same way the hull
:> :>:fails. it splits and the pressure sprays in. water is everywhere
:> :>
:> :>Water with 30+ atmospheres pressure behind it doesn't 'spray', Vinnie.
:> :
:> :Really? I'm looking at a Coleman Powermate pressure washer that
:> :delivers a spray of water at 238 ATM (3500 PSI).
:>
:> Gee, so why would submarine hulls ever collapse? Surely they're
:> stronger than your pressure washer!
:
:OFCS Scuba tanks hold 3500 psi. you can build a hull as thick as you
:want.
Are you saying that the pressure hull on a submarine isn't as thick as
the walls of a scuba tank?
:the Titanic is at 12,000 FSW.
Yes, and with the same pressure on both sides of the hull.
:We just don't build subs that thick since it doesn't make sense.
:(as you well know
I'm trying to break you out of 'surface thinking' where water just
sprays into air, Vinnie. Unlock your head, Ted...
:sheesh
Sheesh, indeed.
Has anyone else noticed that Vinnie uses "sheesh" when he is at a loss
for argument?
Fred J. McCall
Yes, 'it' does. Faster to the point where you don't get 'droplets and
vapor'. You get a solid wall of water.
Vince
solid wall of water hitting steel
lots of foam and droplets everywhere
Vince
Vince
> Vince <fir...@firelaw.us> wrote:
>
> :Fred J. McCall wrote:
> :> David Phillips <david.p...@sas.com> wrote:
> :>
> :> :On Thu, 20 Jul 2006 00:55:12 GMT, Fred J. McCall
> :> :<fmc...@earthlink.net> wrote:
> :> :
> :> :>Vince <fir...@firelaw.us> wrote:
> :> :>
> :> :>:Peter Skelton wrote:
> :> :>:>
> :> :>:> No we aren't. It starts with a leak (which propogates) and one
> :> :>:> compartment fills. When the pressure rises enough catastrophic
> :> :>:> and sudden failure of a bulkhead results. The diesel thing
> :> :>:> follows in the space behind the bulkhead.
> :> :>:
> :> :>:its still "open to the sea" the bulkhead fails the same way the hull
> :> :>:fails. it splits and the pressure sprays in. water is everywhere
> :> :>
> :> :>Water with 30+ atmospheres pressure behind it doesn't 'spray', Vinnie.
> :> :
> :> :Really? I'm looking at a Coleman Powermate pressure washer that
> :> :delivers a spray of water at 238 ATM (3500 PSI).
> :>
> :> Gee, so why would submarine hulls ever collapse? Surely they're
> :> stronger than your pressure washer!
> :
> :OFCS Scuba tanks hold 3500 psi. you can build a hull as thick as you
> :want.
>
> Are you saying that the pressure hull on a submarine isn't as thick as
> the walls of a scuba tank?
>
thickness depends on material
taks are often aluminim, steel is thinner
> :the Titanic is at 12,000 FSW.
>
> Yes, and with the same pressure on both sides of the hull.
>
> :We just don't build subs that thick since it doesn't make sense.
> :(as you well know
>
> I'm trying to break you out of 'surface thinking' where water just
> sprays into air, Vinnie. Unlock your head, Ted...
>
in a sub, with air at STP water, under high pressure, sprays into air
> :sheesh
>
> Sheesh, indeed.
>
> Has anyone else noticed that Vinnie uses "sheesh" when he is at a loss
> for argument?
no when someone as bright as you says something silly
Vince
Vince
it still hits a steel wall
Vince