Israel, There are only three temperatures to worry about: Hot, Damn Hot and Ouch. For something approaching a definition look in BS 4086 Recommendations for Maximum Surface Temperatures of Heated Domestic Equipment. The other excellent standard for defining the issue is EN 563:1994 Safety of machinery - Temperatures of touchable surfaces - Ergonomics data to establish temperature limit values for hot surfaces. The former standard has been used for many years in the UK by enforcement officers to pursue prosecutions, which is where I came across it. The latter standard is listed as a Machinery Directive document and it contains some really useful graphs of exposure time vs. temp. I refer to these regularly when testing equipment in-situ, especially laboratory and semiconductor manufacturing systems as many standards do not leave room for non-specified applications, or are vague. Your point about hot air streams is interesting and you may want to refer to the EN 60335 family of standards for guidance. As an ex-cooking product designer, the temperature of an air stream was not a regulatory requirement. It is difficult to measure accurately and hence was not called up in standards. It was an issue with respect to users, however.
Alan ________________________________________________________________________ _ Alan Brewster Compliance Certification Services 1366 Bordeaux Drive Sunnyvale, CA 94089-1005 Tel: 408-752-8166 ext. 122 Fax: 408-752-8168 e-mail: abrews...@ccsemc.com http://www.ccsemc.com > -----Original Message----- > From: Israel Yeshurun [SMTP:israel_yeshu...@stcl.scitex.com] > Sent: Thursday, October 07, 1999 3:43 AM > To: 'emc-p...@ieee.org' > 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 > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to majord...@ieee.org > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to ed.pr...@cubic.com, > jim_bac...@monarch.com, ri...@sdd.hp.com, or > roger.volgst...@compaq.com (the list administrators). > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
