Of course a piece of metal is really hot at 70 degrees !
One should keep in mind that safety standards are related to
safety, not to prevent discomfort.
Even when falling onto it, one may rise (and shine) before a serious
burn occurs.
70 degrees C (25+45) is a well established limit throughout many many
safety standards
and can be used as a general "no further test required" signal for office
and IT equipment.
( seen from the point of customer; not the test house ;<))
The heated air issue is very different, remember a sauna where the Finnish
(and many others),
use to stay for over 30 minutes at over 80 degrees before jumping into the
snow,
and compare that to the serious injuries one gets when touching the
air/vapor mixture
coming for a cookery pan. Humidity is an issue here. Air flow speed is too
!
Regards,
Gert Gremmen Ing.
== Ce-test, Qualified testing ==
Consultants in EMC, Electrical safety and Telecommunication
Compliance tests for European standards and ce-marking
Member of NEC/IEC voting committee for EMC.
Our Web presence: http://www.cetest.nl
List of current harmonized standards http://www.cetest.nl/emc-harm.htm
15 great tips for the EMC-designer http://www.cetest.nl/features01.htm
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Israel Yeshurun
Sent: donderdag 7 oktober 1999 12:43
To: '[email protected]'
Subject: Hot Surface. Hot air.
Dear Group Fellows
I would like to raise the following two issues:
1) UL1950 / EN60950 Safety standards, Subclause 5.1 - Heating, Table
16 part 2, specify permissible temperature rise for external surfaces of
equipment in Operator Access Area..
For external surfaces, made of metal which may be touched, it allows
temperature rise of 45 degrees Kelvin, assuming ambient temperature of 25
degrees Celsius it allows surface temperature of 70 degrees Celsius = 158
degrees Fahrenheit !
Note (4) in this table applies to external surfaces that are not likely
to be touched in normal use and measure less than 50 mm, in this case it
allows a temperature rise of 75 degrees K, that under 25 degrees C ambient
allows
100 degrees C = 212 degrees F !!
Now, 70 degrees C for external equipment surface that may be touched
seems pretty high to me. 100 degrees C metal surface will, I believe, cause
a burn to that part of the human body that touched it.
So maybe my interpretation is not true ?? and, can someone point
another regulatory source for Hot surface permissible temperature ?
2) Regarding Hot air flowing out of equipment, in UL1950 / EN60950 I
could not find a requirement or limit for the maximum permissible
temperature for it, Can someone point another regulatory source for Hot air
permissible temperature ?
Note: The equipment I relate to is ITE or Office, but information from
Machinery standards or other sources is welcome !
Many Thanks
Israel Yeshurun
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