approx. what temperature causes pain to human skin?

  • Thread starter Thread starter Alex Hunsley
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A

Alex Hunsley

Slightly odd question.. but in absence of a real themometer, it may help me.
What sort of temperature of metal (i.e. a hard disk outer surface) is
needed for contsant contact with the skin to be painful? (after about 5
seconds contact?)

cheers
alex
 
Alex Hunsley said:
Slightly odd question.. but in absence of a real themometer, it may help me.
What sort of temperature of metal (i.e. a hard disk outer surface) is
needed for contsant contact with the skin to be painful? (after about 5
seconds contact?)
Click to expand...

If a HD is hot enough such that you can't hold your hand on it comfortably
for 30 seconds then it's too hot.
 
Alex said:
Slightly odd question.. but in absence of a real themometer, it may help me.
What sort of temperature of metal (i.e. a hard disk outer surface) is
needed for contsant contact with the skin to be painful? (after about 5
seconds contact?)

cheers
alex
Click to expand...

Buy yourself a soldering workstation with temp. controlled iron.

Switch it up to 500deg. C.

Hold the business end of the iron.

Switch it on.

When you drop it, take note of the temperature it has reached.
 
If a HD is hot enough such that you can't hold your hand on it comfortably
for 30 seconds then it's too hot.
Click to expand...

Do you have any idea what temperature is too hot to hold your hand on?
It's suprisingly low. You only have to a get a few degrees above body
temperature for metal to be uncomfortable hot. 50 degrees is
definitely unpleasant, but it won't kill a harddisk.

If we use your definition, it would mean that lots and lots of scsi
drives that have been working fine for many years in servers are too
hot...

Marc
 
Marc said:
Do you have any idea what temperature is too hot to hold your hand on?
It's suprisingly low. You only have to a get a few degrees above body
temperature for metal to be uncomfortable hot. 50 degrees is
definitely unpleasant, but it won't kill a harddisk.

If we use your definition, it would mean that lots and lots of scsi
drives that have been working fine for many years in servers are too
hot...
Click to expand...

If the drive capsules are that hot there's something wrong with the cooling.
I've never encountered a drive that was too hot to touch in a purpose-built
server from any of the major players. 50C on the surface of the chips
maybe.
 
Marc said:
Do you have any idea what temperature is too hot to hold your hand on?
It's suprisingly low. You only have to a get a few degrees above body
temperature for metal to be uncomfortable hot. 50 degrees is
definitely unpleasant, but it won't kill a harddisk.
Click to expand...

Interesting. A tech guy at my local computer shop said around 45 degrees C or
above gets uncomfortable to the skin...
 
J. Clarke said:
Marc de Vries wrote:




If the drive capsules are that hot there's something wrong with the cooling.
I've never encountered a drive that was too hot to touch in a purpose-built
server from any of the major players. 50C on the surface of the chips
maybe.
Click to expand...

I'm thinking of my MaxLine Plus II drive. The chip surfaces definitely get very
hot, but a lot of heat ends up on the other side of the drive and the sides of
the drive, making it very hot.

This drive has operating temperatures up to 55C. Now, does this means that any
temperature it gets to (of its own accord) that is <55 is ok, or could it still
be faulty? The disk just seems to get too hot. Reviews of this disk reveal that
it should get 20degrees above ambient temperature, but I'm pretty sure my disk
is getting hotter than that....

alex
 
On Thu, 01 Jul 2004 13:48:34 +0100, Alex Hunsley

Interesting. A tech guy at my local computer shop said around 45 degrees C or
above gets uncomfortable to the skin...
Click to expand...

Well, I don't know the exact temperature when it gets painful. So,
there is some margin of error in that 50 degrees. I just remember that
it is suprisingly close to your body temperature.

Probably because such temperatures are already pretty unhealthy for
the cells in your body. Proteins start to change at temperatures like
45 and 50 degrees. (some a bit lower some a bit higher)


Harddisk specifications state maximum ambient temperatures of 55
degrees. The HD itself will be warmer with ambient temperatures like
that.

Marc
 
On Thu, 01 Jul 2004 13:48:34 +0100, Alex Hunsley


Well, I don't know the exact temperature when it gets painful. So,
there is some margin of error in that 50 degrees. I just remember that
it is suprisingly close to your body temperature.

Probably because such temperatures are already pretty unhealthy for
the cells in your body. Proteins start to change at temperatures like
45 and 50 degrees. (some a bit lower some a bit higher)
Click to expand...

Decades ago we were told in 2nd year botany that the thermal death
point of plants is around 42C, so I guess it depends how evolved you
are. ;-)

From the Australian kidsafe site:
http://www.greenweb.com.au/kidsafe/html/controlling_hot_water.html
<quoting>
Controlling Domestic Hot Water Temperatures
How Hot is TOO Hot?
60° C major burn in 1 second
55° C major burn in 10 seconds
50° C major burn in 5 minutes
Harddisk specifications state maximum ambient temperatures of 55
degrees. The HD itself will be warmer with ambient temperatures like
that.
Click to expand...

Interesting. The operating specs for both Dells of my personal
acquaintance (4100 and 4600) list the max operating ambient
temperature as 35C, so I guess something else must die before the HDD?


Cheers, Phred.
 
Phred said:
Interesting. The operating specs for both Dells of my personal
acquaintance (4100 and 4600) list the max operating ambient
temperature as 35C, so I guess something else must die before the HDD?
Click to expand...

No. 35C ambient plus the temperature rise between external air and
internal air means the HD internals and the CPU may be pushing 55C.

Good case design should have enough air flow to minimize the rise in
temp, but Dell -- like all commodity PC vendors -- is more likely to
minimize cost than temp.rise.
 
Slightly odd question.. but in absence of a real themometer, it may help me.
What sort of temperature of metal (i.e. a hard disk outer surface) is
needed for contsant contact with the skin to be painful? (after about 5
seconds contact?)
Click to expand...

If I remember correctly, the commercial max temperature spec of 85C was
chosen as a safe temperature for people so it probably gets painful in the
80-85C range.
 
On Wed, 30 Jun 2004 23:57:59 +0100, Alex Hunsley

}What sort of temperature of metal (i.e. a hard disk outer surface) is
}needed for contsant contact with the skin to be painful? (after about 5
}seconds contact?)

For hot water to cause a burn (scald), it takes something like 130-135F
(54.4-57.2C).
 
Phred said:
Decades ago we were told in 2nd year botany that the thermal death
point of plants is around 42C, so I guess it depends how evolved you
are. ;-)

From the Australian kidsafe site:
http://www.greenweb.com.au/kidsafe/html/controlling_hot_water.html
<quoting>
Controlling Domestic Hot Water Temperatures
How Hot is TOO Hot?
60° C major burn in 1 second
55° C major burn in 10 seconds
50° C major burn in 5 minutes


Interesting. The operating specs for both Dells of my personal
acquaintance (4100 and 4600) list the max operating ambient
temperature as 35C, so I guess something else must die before the HDD?
Click to expand...

FWIW, the Seagate Cheetah 15K spec says that the maximum air temperature is
55C, but to achieve the specified MTBF the temperature of the drive casing
should not exceed 50C, with 60 allowable for very short periods.

Any competent engineer puts in some margin above and beyond the
manufacturer's rating, so as a matter of good practice those drives should
be kept at a lower temperature if possible. If you go for 20% margin that
puts you down to 40C, 3 degrees above body temperature.

The "keep your hand on it" test is a rule of thumb--a baker is going to be
able to keep his finger on something a bit hotter than most people for
example.
 
Marc de Vries said:
Do you have any idea what temperature is too hot to hold your hand on?
It's suprisingly low. You only have to a get a few degrees above body
temperature for metal to be uncomfortable hot. 50 degrees is
definitely unpleasant, but it won't kill a harddisk.
Click to expand...

That's flat FALSE. 50 C will certainly diminish the life of a HD. Keep em
40 C or cooler for longest life.
If we use your definition, it would mean that lots and lots of scsi
drives that have been working fine for many years in servers are too
hot...
Click to expand...

You are just wrong!
 
J. Clarke said:
FWIW, the Seagate Cheetah 15K spec says that the maximum air temperature is
55C, but to achieve the specified MTBF the temperature of the drive casing
should not exceed 50C, with 60 allowable for very short periods.
Click to expand...
The Fuji MAN manual gives operating life at average temperatures:
<40C 5 years
<45C 4.5 years
<50C 4 years
<55C 3.5 years
 
That's flat FALSE.
Click to expand...

Care to supply proof?
50 C will certainly diminish the life of a HD. Keep em
40 C or cooler for longest life.
Click to expand...

Most harddisk specs list 55 degrees as ambient temperatures. Please
tell the HD manufacturers that they are wrong!
You are just wrong!
Click to expand...

You are ignoring the official harddisk specs and are not supplying any
proof of your beliefs.
Unless you change that I see very little crediblity in your
statements.

Marc
 
Marc de Vries said:
Most harddisk specs list 55 degrees as ambient temperatures. Please
tell the HD manufacturers that they are wrong!
Click to expand...

Something is clearly wrong here. There's hardly anywhere on Earth
outside an oven where the ambient air temperature reaches 55C.
(Or is that "55 degrees" meant to be 55F? -- I guess that would
explain it! :)


Cheers, Phred.
 
Phred said:
Something is clearly wrong here. There's hardly anywhere on Earth
outside an oven where the ambient air temperature reaches 55C.
(Or is that "55 degrees" meant to be 55F? -- I guess that would
explain it! :)
Click to expand...

That's not actually an "ambient temperature", its the temperature of the air
flowing over the disk, which air might have been circulating around inside
a computer for a bit.
 
Marc de Vries said:
Care to supply proof?
Click to expand...

Anybody who reads the thread can see that for themselves.
Most harddisk specs list 55 degrees as ambient temperatures. Please
tell the HD manufacturers that they are wrong!
Click to expand...

No, you simply can't read HD specs.
You are ignoring the official harddisk specs and are not supplying any
proof of your beliefs.
Unless you change that I see very little crediblity in your
statements.
Click to expand...

Clueless.
See:
The Seagate 10K6 technical spec
http://www.seagate.com/cda/products/discsales/enterprise/tech/0,1084,538,00.html
"Operating Temperature (max) 55 deg C"

Now that's the case(casting) temperature and nothing about ambient as most
all HD mfgs specs show.
That's the drop dead case temp.

Run a drive at 40C case(casting) temp or less for max life.
 
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