Freezing a HDD

[Rod Speed]

Gerald Abrahamson wrote
Lack of one provided noted.

You are both on the right track.
Nope.

The pure nitrogen will tend to diffuse out of the bag
until the replacement rate is the same as the loss rate.

Wrong, because the bag just collapses a bit if a bit of the
internal nitrogen does actually diffuse out of the bag faster
than a bag which contains just air instead would.

As that is a partial pressure vacuum within the bag fairly quickly,
that will cause the outside air to try to equalize pressure inside the bag.

Nope, because the bag just collapses a bit if a bit of the
internal nitrogen does actually diffuse out of the bag faster
than a bag which contains just air instead would.

The bag is *folded* over the end--not actually
hermetically *sealed* to keep out air.

So it isnt even possible for it to have a different pressure
inside the bag than there is outside the bag, so it isnt
even possible to get a vacuum inside the bag.

That folding is adequate to keep out normal air contamination--

Mindlessly silly.

but it would fail to do so if the bag was initially filled with pure nitrogen.

Even sillier.

The new partial vacuum would cause dirt, dust, etc to be "drawn in" through/past the folds

Even sillier. The bag would just collapse a bit if the pure nitrogen inside the
bag actually did diffuse out of the bag faster than air inside the bag would.

because the bag wall does NOT act as a filter (which it
does for atoms/molecules going *through* the bag wall).

Completely off with the ****ing fairys, as always.

No wonder you got the bums rush, right out onto your lard arse.

 

[Rod Speed]

David Brown wrote

Rod Speed wrote

Tho nitrogen is used in car tires for a reason, it
does diffuse out marginally less easier than air does.

Please switch off the Rodbot mode

Nothing bot about it.

if you want to have an adult conversation.

Usual utterly bogus flagrantly dishonest language.

Try <http://en.wikipedia.org/wiki/Partial_pressure> for some basics.

Dont need to, I got formally qualified in that stuff before you were even born thanks.

The gases all act independently.

There is no independantly when its filled with JUST nitrogen, thats all there is.

The /total/ pressure of the mixture in air is the some of the partial pressures of N2, O2, and trace gases.

Irrelevant to what happens when its filled with JUST nitrogen.

Thus in air, there is a partial pressure of 0.78 atmospheres of N2.

Inside the bag with a /total/ pressure of 1 atmosphere, but only N2, you have a partial pressure of 1 atmosphere of
N2.

All completely irrelevant to that stupid pig ignorant claim that
nitrogen diffuses out of the bag when there is JUST nitrogen
in the bag but that doesnt happen with air in the bag.

Therefore the N2 in the bag is at a higher pressure,

No it isnt in the sense of what is driving the diffusion of the nitrogen.

and will - if able - diffuse out to the surrounding air in an attempt to equalise that pressure.

That is just plain wrong.

What determines the rate at which the air or the nitrogen
alone diffuses out of the bag is the total pressure in the bag.
The partial pressure of the nitrogen is completely irrelevant.

The reason car tires are filled with nitrogen instead of air is
because the nitrogen molecule is marginally bigger and so
it diffuses out marginally less than the air does and because
its dry nitrogen so you dont get any water in gas thats used
to inflate the tires.

Similarly, the partial pressure of O2 in the air is 0.21 atmospheres, while the partial pressure of O2 inside the bag
is 0. So O2 will diffuse into the bag.

Using that mindlessly silly line, the partial pressure when the bag
is filled with just nitrogen is zero, so it should pour into the bag at
a much higher rate than it does with air in the bag. In practice it doesnt,
and thats why tires are filled with nitrogen, because that doesnt happen.

The only things that will stop this process is having air-tight bags and seals,

That wont stop that happening, because the bag still sees some gas
diffuse thru the bag material. Thats why balloons deflate over time.

or the bag's volume (of gas) being reduced to 0.

Not even possible. You never see the bag end up like
it does if you deliberately evacuate all the air out of
the bag like you do with those freezer bag systems.

As long as the partial pressure of N2 in the bag is higher than that outside, it will continue to diffuse through the
bag

Wrong. The rate of diffusion has nothing to do with the partial pressure.

If it did, a bag with just nitrogen inside it would end up
with oxygen inside the bag because the partial pressure
of the oxygen is zero. That doesnt in fact happen at all.

And its completely trivial to prove that it doesnt happen
by filling a bag with nitrogen, say down at the tire retailler,
leaving it for a while and then seeing if you can get a lighted
split to keep burning when you put it into the bag. It doesnt,
it goes out, because the bag doesnt contain any oxygen.

(or the open end of the bag, obviously).

The N2 will diffuse out faster if it is at a higher partial pressure
than then outside air.

Wrong. Using that mindlessly silly line, oxygen would diffuse into
the bag much more quickly because the partial pressure of oxygen
inside the bag is zero. It doesnt and you can prove it doesnt as above.

Similarly, the O2 will diffuse faster into the bag as long as the partial pressure outside is higher than that inside
the bag.

Utterly wrong and trivial to prove that its utterly wrong.

Usual that mindlessly silly line it would never be possible to
ever keep any gas in a bag because oxygen and nitrogen
would diffuse into the bag because the partial pressure of
oxygen and nitrogen inside the bag is zero.

I know that doesnt happen because we used to keep bloody great
bags of helium when I was getting formally qualified in this area
before you were even born, because its such an expensive gas.

Three things affect the speed of the diffusion - the temperature
(higher temperature means more diffusion), greater difference in partial pressure, and lower "resistance" to
diffusion.

You've mangled the story completely on the partial pressure as I showed above.

Smaller molecules, or leakier bags, will allow faster diffusion.

A hydrogen or helium balloon is a very different situation from the bags we are discussing.
Nope.

One obvious factor is that the partial pressure outside the bag is zero, while the partial pressure inside is high,

Thats not partial pressure, thats total pressure.

so there will be fast diffusion.

Nope, there is fast diffusion because its a MUCH smaller molecule.

Secondly, the total pressure inside is much higher than atmospheric pressure.

Utterly mangled all over again once the balloon is going flat.

And using your mindlessly silly line, the balloon wouldnt go flat
because you claim that the nitrogen and oxygen in the air outside
the balloon would be pouring into the balloon because the partial
pressure of those inside the balloon would be zero.

And thirdly, the elasticity of the rubber pulls the balloon closed when the pressure inside drops - completely unlike
the case of a plastic bag.

Exactly like the plastic bag when the balloon has deflated.

If you were to examine the gas content of the balloon after a while, you would see that there is in fact a small
amount of N2 and O2 inside the balloon

No there is not. And its completely trivial to prove
that there isnt with a bag filled with just nitrogen.

- since there is a higher partial pressure of theses gases outside the balloon than inside.

In fact there is a MUCH higher partial pressure
because the partial pressure inside is initially ZERO.

It will only be trace amounts for a good helium balloon, since the material is almost impenetrable to such large
molecules.

Utterly mangled all over again. Balloons filled with air ALSO deflate
over time, just at a lower rate than balloons filled with hydrogen or helium.

But if you had an ordinary balloon filled with helium, more N2 and O2 would get in.

Doesnt happen, and its completely trivial to prove that it
doesnt happen with balloons filled with helium and nitrogen.

And know it didnt happen with the ****ing great bags of helium we used
because the cost of the helium was so high that it was worth saving.

And that was with instrumentation that would have got poisoned
with oxygen or nitrogen getting into those bags. Didnt happen
because the pressure of HELIUM inside the bags was high
enough to ensure that there was no diffusion of air into the
bags even tho the partial pressure of nitrogen and oxygen
inside those bags was quite literally ZERO.

 

[Rod Speed]

Rod Speed wrote

It is correct that N2 molecules diffuse out a little slower through the tire rubber. But the main benefit of N2 in
tires is to avoid the corrosive effects of the O2

Nope, that obviously does nothing about the rubber
thats on the outside of the tire exposed to the air.
And tires dont wear out from the inside either.

- just as in most cases where an N2 atmosphere is used rather than air.

Thats wrong too. The main reason its used because its
dry, so you dont get internal condensation in cameras and
binoculars etc when they are used in very cold conditions.

There is no internal corrosion to speak of.

I know it's pointless really, but I'll give this one more shot.

Wota stunning line in rational argument you have there...

What "formal qualifications" do you have, except perhaps certified senility?

And this is your idea of adult conversatiion is it, you pathetic excuse for a bullshit artist ?

Try tertiary degrees, child.

I never claimed any such thing

Everyone can see for themselve that you did indeed claim that
because the partial pressure with just nitrogen in the bag is higher
than with air in the bag, that the nitrogen would diffuse out of the
bag at a higher rate than when air is in the bag. Thats just plain
wrong. It would in fact diffuse out of the bag at a lower rate just
because nitrogen molecules are a bit bigger than oxygen molecules.

- I did not discuss the situation with just air in the bag.

Everyone can see for themselves that you did when you said
what the partial pressure of nitrogen is with air in the bag.

If there is just air in the bag, then the partial pressures of the components will be in the same ratio as for the
outside air, obviously. If the total pressure in the bag is greater than that of the atmosphere, there will be a
diffusion out. If it is lower, there will be a diffusion in.

Irrelevant to what is being discussed, the difference
between just nitrogen in the bag and air in the bag.

And we arent discussing higher or lower pressures than outside
either, because the bags arent inflated, they are just filled with
either nitrogen or air at atmospheric pressure.

For a high pressure bag of air, the rate of diffusion of the different gases is dependent on the difference in partial
pressure between the inside and the outside,

Wrong. As I said, using that line, with just nitrogen ikn the bag, the
partial pressure of oxygen in the bag would be zero and that would
using your utterly mangled line see a lot more oxygen enter the bag
from outside the bag than with air in the bag. In fact that doesnt
happen and I told you how to prove that using rigorous science
that anyone can try for themselves.

and the "resistance" of the material to the different gases. To begin with, the partial pressures are all in the same
ratio as air, but the O2 will pass through the material somewhat faster.

But in both directions.

(This is not due to the physical size differences

Wrong again.

- although N2 is bigger than O2, the size difference is negligible - there are other effects here causing faster
diffusion of O2 to diffuse three or four times faster than N2 through rubber.)

We arent talking about rubber with hard drive bags.

Thus the percentage of O2 in the bag will drop.

Wrong, because it diffused in BOTH directions faster than nitrogen.

Another howler.

The rate of diffusion of the O2 will slow down faster than for the N2, of course, since you are getting exponential
decays until all the pressures balance out.

Utterly mangled all over again, and it isnt exponential either.

Yes it is - it is the partial pressures that drive the diffusion, not the total pressure.

It clearly isnt when you dont see the oxygen outside the
bag diffusing into the bag when the bag is filled with nitrogen
so the partial pressure of oxygen inside the bag is zero.

Incorrect.

Nope, you are. As I proved with pure nitrogen in the bag and so
a partial pressure of zero with oxygen.

The main reason for using N2 is that it is inert, and does not gradually corrode th e rubber in the way O2 does.

Wrong. You still get the corrosion outside the tire and even
you should have noticed that tires get replaced because they
have perished on the outside, not the inside, when they arent
replaced due to the tread having been worn off on the road.

It is also (apparently) easier to ensure the N2 is free of any water, which improves fuel efficiency

Like hell it does to any significant degree in real life.

In real life its the tire PRESSURE that matters for fuel efficiency much more.

and tire life. A secondary benefit is that N2 diffuses out slower than O2 through the rubber - although not because
of differences in the size of the molecule (since the differences are tiny).

Utterly mangled all over again.

Please try to remember that a simple plastic bag with the end folded over is not particularly gas tight, while a thick
rubber tire is designed to be as gas tight as practically possible.

Irrelevant to that point I was rubbing your nose in there.

The diffusion rates are reflected in this.

Utterly mangled all over again.

Yes, O2 tries to pour into the N2-filled bag. When it can do so easily, it does so.

How odd that you cant actually detect any there using the test I rubbed your nose in.

Yes, O2 tries to pour into the N2-filled tire. Since the tire offers a rather high resistance to O2 molecules, it
diffuses in very slowly.

It doesnt diffuse in AT ALL.

The rate is a bit slower than the diffusion of O2 molecules out of an air-filled tire,

If your howler about partial pressures was true, it would be much faster.

because the difference in partial pressures is less (21% * 1 atmosphere vs. 0 for O2 into an N2-filled tire, compared
to 21% * 2.5 atmosphere vs. 21% * 1 atmosphere for O2 out of an air-filled tire at typical pressures).

Yet another ridiculous howler.

Balloons are not airtight - that's why air can get through them.

That added absolutely nothing to what I just said.

The conclusion is thus that O2 will diffuse into the bag.

Have fun explaining why it doesnt with those freezer bag systems.

Keep desperately digging, you'll be out in china any day now.

It will, in fact, happen.

Nope, and I rubbed your nose in how to prove that it doesnt.

You may have to wait a very long time to get enough oxygen to keep a flame alight, depending on the resistance of the
bag to the O2 molecules.

Pathetic. You can wait a year if you like, it still wont happen.

Also not that in the case of a tire or a balloon, there is the additional effect of the elasticity of the container
resisting anything coming in.

Yet another howler with balloons. Its got nothing to do with elasticity
its just the porosity of the membrane and thats actually less with
balloons than with the sort of plastic bags used for hard disk drives.

Thats why some of the modern packing systems just
use inflated sealed plastic bags as packing material.

A bag that is capable of holding helium for any length of time will be almost impervious to O2.

Thanks for that completely superfluous proof that you have
never ever had a ****ing clue about the most basic physics.

I would have thought that much is obvious.

(drivel snipped to save time and space.)

More of your flagrant juvenile dishonesty.

Translation: I couldnt refute anything so I just deleted it and tried to pretend it was drivel.

Wota pity you are fooling absolutely no one at all with your juvenile stunt.

 

[Rod Speed]

Then there is the breather hole in the drive Rod has
completely forgotten (again).

Everyone can see for themselves that I in fact rubbed
YOUR stupid pig ignorant nose in that right at the start. liar.

When the "pure nitrogen atmosphere" he proposes
diffuses down to a partial pressure,

Not even possible. If it starts out pure nitrogen and some
of that nitrogen diffuses out of the bag, its STILL got the
same partial pressure because thats all there is in there.

the air pressure inside the drive itself will equalize via the breather hole.

Nope, because the pressure in the bag doesnt change,
even if some of the nitrogen does diffuse out of the bag,
because the bag will just collapse marginally.

And that is is NOT good.

Even sillier. That port is designed for that to happen as the
atmospheric pressure the drive is experiencing changes.

Rod forgot his physics--AGAIN. And he forgot the
drive has that breather hole for a reason--air pressure.

Everyone can see for themselves that I in fact rubbed
YOUR stupid pig ignorant nose in that right at the start. liar.

What will happen (in Rodbot's "yet another failed"
theoretical world) is the drive will equalize and them
maintian that partial pressure until it reaches its final
destination--and is opened. As soon as that happens
(drive unwrapped), the drive will begin to draw in air
to re-equalize to the new--and higher--air pressure.

There is no new pressure when the bag is opened, as you
said, the bag isnt sealed, its just got the end folded over.

This will cause all kinds of airborn crap
to pulled into the drive via the breather hole

Mindlessly silly. That hole has a filter, child.

Because the air pressure outside the drive changes all the time
when the drive is installed in the system outside the bag, child.

(because the drive itself was ALSO at partial pressure

You're utterly mangling the use of that term child.

due to the the partial pressure in the bag compared
to the outside air pressure). Any type of filter installed
could easily become clogged or even totally blocked
due to the relatively large--and unanticipated--volume
of air being pulled in at one time.

There is not relatively large volume of air and air cant block a filter anyway, child.

I dont believe you ever worked anywhere, you dont
have a ****ing clue about the most basic physics.

 

[larry moe 'n curly]

It is correct that N2 molecules diffuse out a little slower through the
tire rubber. But the main benefit of N2 in tires is to avoid the
corrosive effects of the O2 - just as in most cases where an N2
atmosphere is used rather than air.

So why does 100% N2 cause valve stem caps to turn from black to an
undesirable green?

 

[Mike Tomlinson]

More BS. In transit, drives are essentially sealed. So the
only way they get condensation inside the package is through
failed packaging or improper preparation at the factory.

And they also pop in a sachet of silica gel desiccant to be on the safe
side.

You're wasting your time arguing with Woddles; he's the group troll.

 

[kattyjohn012]

Any computer user knows how frustrating it is when a PC stops running in the middle of a complex application. If your laptop keeps freezing when you’re in class or in the field doing research, there’s not much you can do to salvage your notes. Computers sometimes freeze, but if a computer freezes on startup regularly, or if it freezes when multi-tasking, there’s probably something wrong. A computer could suffer permanent damage when it stops running abruptly.
Save your work often. If you are on the Internet often, save your work as a draft and come back to edit it. In case you are working on a document, click the save button every so often. This is a quick fix in the event your computer freezes.
Press Control-Alt-Delete to fix a stalled computer. This will bring up your Windows Task Manager. It will appear differently in different versions of Windows, just so you are aware. The computer will tell you which software is responding and which is not responding or freezes up continually.


datarecovery