Rice and the absorbing power it holds

[imatfaal]

Table salt is far more hygroscopic than rice isn't it?  The problem with salt is that you really do not want salty water near your electronics or even bare metal in general

[John Cuthber]

One word of warning, if the phone is, or contains, sealed areas then putting it in a vacuum chamber might be a very bad idea.

[DrP]

Good point John, I guess I didn't think of that. I wasn't talking UHV though...  just the reduced pressure of a vac oven. Would the battery suffer under reduced pressure as it is sealed?

I once broke the UHV on an SEM machine...  Took all night to vac it back down. I thought I 'd look at a dead wasp at the end of the day after most had gone home and I had finished my work...  I coated it with a layer of gold first and put it in the machine, not thinking that as it was a bit fresh there would be some 'sealed areas' of it in tact still. These sealed areas popped under the vac and I had to remove the thing and totally vac it down again all night. I was worried at first in case I had broken the machine by covering the insides with wasp insides, but it wasn't that bad, just lost the vacuum until the next day. 

 

[John Cuthber]

"I wasn't talking UHV though"

 

AARgh!

It's another person who seems to think that the depth of the vacuum matters to whether or not something going to burst.

The air in the bug is at about 760 mm Hg.
With the crappy vacuum you get with a water jet pump- say 30 mm Hg the pressure difference between the inside and the outside is 730mm

If you use a UHV system the pressure difference is 759.999 mmHg

Unless the bug skin's failure pressure differential happens to be between 730 and 759.999 the fate of the bug is going to be the same whichever pump you use.
Every now and then people get injured because they hook a normal flask or beaker to a water jet pump thinking "it's not a very good vacuum- so it won't implode".

It's not the vacuum that does the work, it's the atmosphere outside - and that's just the same no matter what pump you use.

[Bender]

4 hours ago, John Cuthber said:

"I wasn't talking UHV though"

 

AARgh!

It's another person who seems to think that the depth of the vacuum matters to whether or not something going to burst.

The air in the bug is at about 760 mm Hg.
With the crappy vacuum you get with a water jet pump- say 30 mm Hg the pressure difference between the inside and the outside is 730mm

If you use a UHV system the pressure difference is 759.999 mmHg

Unless the bug skin's failure pressure differential happens to be between 730 and 759.999 the fate of the bug is going to be the same whichever pump you use.
Every now and then people get injured because they hook a normal flask or beaker to a water jet pump thinking "it's not a very good vacuum- so it won't implode".

It's not the vacuum that does the work, it's the atmosphere outside - and that's just the same no matter what pump you use.

Why would phone manufacturers make phones that could pop in an airplane or while climbing a mountain? If the phone can survive that safely, I think it is pretty unlikely to break in a vacuum.

Do you have any indication for sealed areas in consumer electronics? 

[John Cuthber]

7 hours ago, swansont said:

If the phone itself is sealed, the dropping it in water is no big deal in the first place.

15 minutes ago, Bender said:

Why would phone manufacturers make phones that could pop in an airplane or while climbing a mountain? If the phone can survive that safely, I think it is pretty unlikely to break in a vacuum.

Do you have any indication for sealed areas in consumer electronics? 

Edited July 26, 2017 by John Cuthber

[dimreepr]

12 minutes ago, Bender said:

Why would phone manufacturers make phones that could pop in an airplane or while climbing a mountain? If the phone can survive that safely, I think it is pretty unlikely to break in a vacuum.

1

But that's a different scale of pressure, much like my likelyhood of surviving in100 feet of water, compared to 10.000 feet of water/

[Klaynos]

21 minutes ago, Bender said:

Why would phone manufacturers make phones that could pop in an airplane or while climbing a mountain? If the phone can survive that safely, I think it is pretty unlikely to break in a vacuum.

Do you have any indication for sealed areas in consumer electronics? 

The batteries are sealed units. 

If that breaks things go bad. Whilst they are tested against reasonable pressures such as aircraft pressurised cabins a semi decent vacuum chamber can easily surpass that. 

[swansont]

12 minutes ago, dimreepr said:

But that's a different scale of pressure, much like my likelyhood of surviving in100 feet of water, compared to 10.000 feet of water/

100' of water is ~3 atmospheres of pressure difference, while a vacuum is no more than 1

[swansont]

10 minutes ago, Klaynos said:

The batteries are sealed units. 

If that breaks things go bad. Whilst they are tested against reasonable pressures such as aircraft pressurised cabins a semi decent vacuum chamber can easily surpass that. 

But is there air inside? If it's all solid, it's no big deal.

[Klaynos]

6 minutes ago, swansont said:

But is there air inside? If it's all solid, it's no big deal.

Yes, the electrolyte degrades releasing a flammable gas... (Lithium ion). That's why they swell. 

[dimreepr]

8 minutes ago, swansont said:

100' of water is ~3 atmospheres of pressure difference, while a vacuum is no more than 1

I stand corrected but does that make my point less valid?

[John Cuthber]

If you drop electronic gear into water the best thing to do (after wiping the surface dry) is to remove the battery in order to avoid electrolytic corrosion.

So the state of the (relatively cheap) battery shouldn't matter much.

[Klaynos]

A large fraction of modern phones do not have removable batteries. So removing the battery is not an option. 

[swansont]

1 hour ago, dimreepr said:

I stand corrected but does that make my point less valid?

At the top of a tall mountain, the pressure has dropped to about a half an atmosphere. A factor of 2. You were comparing a factor of 100 increase in pressure. So yes, your point is less valid.

[Bender]

4 hours ago, Klaynos said:

The batteries are sealed units. 

If that breaks things go bad. Whilst they are tested against reasonable pressures such as aircraft pressurised cabins a semi decent vacuum chamber can easily surpass that. 

Is a phone manufacturer going to risk lawsuits when the cabin depressurises and all the phones explode in 0.2 bar ambient pressure? Also see swansont's post above: the pressure difference between what you call "reasonable pressure" and "semi decent vacuum" isn't that impressive.

[Klaynos]

10 hours ago, Bender said:

Is a phone manufacturer going to risk lawsuits when the cabin depressurises and all the phones explode in 0.2 bar ambient pressure? Also see swansont's post above: the pressure difference between what you call "reasonable pressure" and "semi decent vacuum" isn't that impressive.

Whilst I agree with your first point to a degree. The seals do break and batteries do explode, you increase the probability of this by exposure to a strong vacuum. Also this is moving the goalposts I was replying to whether phones have sealed components (they do). Not whether this would be affected by a mild vacuum. 

You're second point I cannot accept. Take a submarine. They're fine to some really quite impressive pressure changes as described by swansont. But if you put it into space you have some very confused submariners who's air would be leaking out. Low pressure and high pressure designs are very different. Now this actually supports the argument that batteries are not too much of an issue as they are designed to stop the gas inside getting out, which is the same design requirement for vacuum operations. But again that isn't what I was replying to originally. 

[Bender]

3 hours ago, Klaynos said:

Whilst I agree with your first point to a degree. The seals do break and batteries do explode, you increase the probability of this by exposure to a strong vacuum. Also this is moving the goalposts I was replying to whether phones have sealed components (they do). Not whether this would be affected by a mild vacuum.

You're second point I cannot accept. Take a submarine. They're fine to some really quite impressive pressure changes as described by swansont. But if you put it into space you have some very confused submariners who's air would be leaking out. Low pressure and high pressure designs are very different. Now this actually supports the argument that batteries are not too much of an issue as they are designed to stop the gas inside getting out, which is the same design requirement for vacuum operations. But again that isn't what I was replying to originally. 

How am I moving goalposts? The question is whether a phone can survive vacuums of different levels of mildness.

Swansont wasn't replying to the fact that it was an increase or a decrease in pressure (which was never the point of the analogy), but that the scale of the pressure difference in dimreepr's analogy was all wrong. I don't understand why you wouldn't agree with that.

[studiot]

I seem to be the only one who reads books these days so here is something I didn't see on facebook or twitter.

It is about cleaning keyboards, but I have also applied it to mobile phones and computer boards more generally, but take batteries out first.