Minimum Humidity for long term storage of computer equipment?

[Peter Olcott]

Is there a minimum level of relative humidity, below which computer equipment is
damaged?

I bought some antique handheld computers. I want to keep them in pristine
condition for a very long time, fifty years or more. I want to know the ideal
environmental conditions to store these computers. I am probably going to store
these in a bank vault. I can greatly reduce the relative humidity using a
commercial desiccant such as drierite.

Thanks for your help.

 

[Jim Thompson]

Is there a minimum level of relative humidity, below which computer equipment is
damaged?

I bought some antique handheld computers. I want to keep them in pristine
condition for a very long time, fifty years or more. I want to know the ideal
environmental conditions to store these computers. I am probably going to store
these in a bank vault. I can greatly reduce the relative humidity using a
commercial desiccant such as drierite.

Thanks for your help.

Is the bank vault hermetically sealed? Or your packaging? If not,
long term, they will return to ambient conditions.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice480)460-2350 | |
| E-mail Address at Website Fax480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Old Latin teachers never die...they just decline

 

[Peter Olcott]

Is the bank vault hermetically sealed? Or your packaging? If not,
long term, they will return to ambient conditions.

My vacuum packaging is hermetically sealed.

 

[Lostgallifreyan]

My vacuum packaging is hermetically sealed.

If you have vaccuum packaging, isn't humidity irrelevant? And, what about
dry nitrogen? For those time scales, you'll want to remove oxygen, not just
water vapour. Vacuum isn't a good idea, as you'll lose plasticisers and
other chemicals that prolong the life of capacitors, and maybe have hazards
that can cause bother in other people's space, but if you have a hermetic
seal with the volume filled with dry nitrogen at atmospheric pressure, you
can't go far wrong, as far as I know.

 

[Peter Olcott]

If you have vaccuum packaging, isn't humidity irrelevant? And, what about

It is nothing like a prefect vacuum, I am only using a foodsaver meat packaging
machine. The idea is to make the package fit tightly, removing all the excess
air

dry nitrogen? For those time scales, you'll want to remove oxygen, not just
water vapour. Vacuum isn't a good idea, as you'll lose plasticisers and
other chemicals that prolong the life of capacitors,

What about reducing the relative humidity to zero?

and maybe have hazards
that can cause bother in other people's space, but if you have a hermetic
seal with the volume filled with dry nitrogen at atmospheric pressure, you
can't go far wrong, as far as I know.

I can't go to this extreme, what is the next cheaper option?

 

[James Thompson]

It is nothing like a prefect vacuum, I am only using a foodsaver meat
packaging machine. The idea is to make the package fit tightly, removing
all the excess air


What about reducing the relative humidity to zero?


I can't go to this extreme, what is the next cheaper option?

If you cant go to a gas refill station and get some nitrogen, next best
thing would maybe be get the small co2 cylinders like used for paintball,
and purge the containers with co2 gas. It will drive out all the oxygen,
which is what causes rust with water vapor. Also use the desecant to absorb
any remaining moisture.

Still nitrogen is best!
Jtt

 

[Ken Finney]

Is there a minimum level of relative humidity, below which computer
equipment is damaged?

I bought some antique handheld computers. I want to keep them in pristine
condition for a very long time, fifty years or more. I want to know the
ideal environmental conditions to store these computers. I am probably
going to store these in a bank vault. I can greatly reduce the relative
humidity using a commercial desiccant such as drierite.

Thanks for your help.

Backfill the bags with dry nitrogen (MIL-PRF-27401, Type 1 Gas, Grade C
(99.995%)), and use Mitsubishi Gas Chemeical American dessicant type RP-5.

 

[Peter Olcott]

If you cant go to a gas refill station and get some nitrogen, next best thing
would maybe be get the small co2 cylinders like used for paintball, and purge
the containers with co2 gas. It will drive out all the oxygen, which is what
causes rust with water vapor. Also use the desecant to absorb any remaining
moisture.

Still nitrogen is best!
Jtt

How could this be packaged to retain the nitrogen / co2 ?

 

[Guest]

: My vacuum packaging is hermetically sealed.

Might be good if all of this sealing didn't generate Electrostatic
Discharge also. Often, pressurized air/vacuum can generate ESD.

I don't know why it's important to keep the computer vs. storing the
data instead. It's likely the capacitors will eventually depolarize
over time if they're not powered up.

some things to think about....

b.

 

[Peter Olcott]

I want to store the computers because there has only been one computer made that
I can use in direct sunlight, fit inside my pocket, with a large enough screen
and keyboard that I can do C++ programming. HP 200LX. They quit making these ten
years ago, and no one has made anything like them since. I bought four of them
so that I will never run out.

 

[Peter Olcott]

Backfill the bags with dry nitrogen (MIL-PRF-27401, Type 1 Gas, Grade C
(99.995%)), and use Mitsubishi Gas Chemeical American dessicant type RP-5.

Is there anyone that can do this as a service?

 

[William P.N. Smith]

Is there a minimum level of relative humidity, below which computer equipment is
damaged?

I don't think there's a minimum humidity, so go ahead and use plenty
of desiccant.

I bought some antique handheld computers. I want to keep them in pristine
condition for a very long time, fifty years or more.

Do these computers have rechargable batteries? If so, there's not
much you can do...

There are commercial oxygen absorbers that look very similar to
desiccants that'll make your air into nitrogen for you. However, your
vacuum-packed plastic may not be as water-tight as you think. I'd
also put a humidity indicator card in each one so you can keep an eye
on the humidity levels.

 

[Peter Olcott]

I don't think there's a minimum humidity, so go ahead and use plenty
of desiccant.


Do these computers have rechargable batteries? If so, there's not
much you can do...

They take any kind of AA penlight battery, I am currently using Duracell 2500
mAh, and getting seventeen hours of continuous use. Before I had the units
upgraded to double their speed they got twenty-seven hours of continuous use.
They run all the programs from the original IBM PC at (an upgraded speed of)
about 1/3 faster than the original IBM AT.

 

[Ken Finney]

Is there anyone that can do this as a service?

Well, White Sands Missle Range.... ;^)

Since vacuum is being used, just using the the dessicant is probably good
enough. Mitsubishi has changed their numbering system, and apparently in is
know known as "RP A-type".

 

[Ken Finney]

: My vacuum packaging is hermetically sealed.

Might be good if all of this sealing didn't generate Electrostatic
Discharge also. Often, pressurized air/vacuum can generate ESD.

I don't know why it's important to keep the computer vs. storing the
data instead. It's likely the capacitors will eventually depolarize
over time if they're not powered up.

some things to think about....

b.

Good point, Aluminum Electrolytic capacitors may not work after 10 years.

 

[Ken Finney]

Well, White Sands Missle Range.... ;^)

Since vacuum is being used, just using the the dessicant is probably good
enough. Mitsubishi has changed their numbering system, and apparently in
is know known as "RP A-type".

Forgot to add:

http://www.mgc-a.com/rpsystem/mgca.html

 

[Lostgallifreyan]

How could this be packaged to retain the nitrogen / co2 ?

Nothing extreme about dry nitrogen. It's the single most abundant gas in
the atmosphere, and you can get it in welder's gas cannisters. To seal it,
just use a plastic bag in a cardboard box, with some freshly baked silica
gel sachets in the bag with the gear. If you can seal the bag so it acts
like an air pillow and resists loss of gas when you try to squeeze it, that
will be fine. As the inside and outside will equalise at atmospheric
pressure, even a pinhole leak won't do much harm for many months, so long
as the box resists compression.

Pack gear, put gel sachet, flush from gas cannister through a tube through
the almost closed bag for a couple of minutes, remove tube, seal, squeeze
to test seal. Close box.

Test seal every year for first five years, by squeezing the bag. It's
very cheap, very basic, and very easy.

 

[Peter Olcott]

Nothing extreme about dry nitrogen. It's the single most abundant gas in
the atmosphere, and you can get it in welder's gas cannisters. To seal it,
just use a plastic bag in a cardboard box, with some freshly baked silica
gel sachets in the bag with the gear. If you can seal the bag so it acts
like an air pillow and resists loss of gas when you try to squeeze it, that
will be fine. As the inside and outside will equalise at atmospheric
pressure, even a pinhole leak won't do much harm for many months, so long
as the box resists compression.

Pack gear, put gel sachet, flush from gas cannister through a tube through
the almost closed bag for a couple of minutes, remove tube, seal, squeeze
to test seal. Close box.

Test seal every year for first five years, by squeezing the bag. It's
very cheap, very basic, and very easy.

The only thing that I would not know how do, after your excellent explanation
would be to find the most cost-effective source of nitrogen gas. It would be
nice If I could buy a couple of cubic feet at Wal-Mart for $2.99. Also would
nitrogen gas be reactive with CaSO4, CoCl2 ?
(That is the composition of my "drierite" desiccant).

 

[Lostgallifreyan]

The only thing that I would not know how do, after your excellent
explanation would be to find the most cost-effective source of
nitrogen gas. It would be nice If I could buy a couple of cubic feet
at Wal-Mart for $2.99. Also would nitrogen gas be reactive with CaSO4,
CoCl2 ? (That is the composition of my "drierite" desiccant).

Thnkyou.
I'm not sure about the reaction, but I doubt it, nitrogen is chosen for
being largely inert. On the other hand it's associated with interesting and
often violent chemistry, so it's worth checking with the maker of your
dessicant. Basic rule is: if a thing doesn't react much with air over time,
ir definetely WILL NOT react with nitrogen under similar temperature and
pressure, as air is mostly nitrogen already.

 

[Peter Olcott]

Thnkyou.
I'm not sure about the reaction, but I doubt it, nitrogen is chosen for
being largely inert. On the other hand it's associated with interesting and
often violent chemistry, so it's worth checking with the maker of your
dessicant. Basic rule is: if a thing doesn't react much with air over time,
ir definetely WILL NOT react with nitrogen under similar temperature and
pressure, as air is mostly nitrogen already.

How can I get nitrogen least expensively?