It would seem that this is one issue of signiicant difference between UL913 and ATEX - UL913 recommends constructing a portable device out of a "non sparking material such as plastic or brass" (clause 14.1). Here UL is addressing a valid concern about the risk of ignition caused by the unit accidentally banging up against something and creating a spark. ATEX does not address this concern, and UL913 doesn't address the concern of ESD caused by a buildup of charge in a material with extremely high surface resistivity.
I'm thinking if I make the enclosure out of Flubber, it would meet all requirements. Anybody got the nutty professor's number? Doug -----Original Message----- From: Linstrom, John (IndSys, GEFanuc, CDI) [mailto:[email protected]] Sent: Thursday, November 16, 2000 5:07 PM To: Massey, Doug C. Subject: RE: Intrinsically safe equipment WE were denied an ATEX approval for a HAZLOC box with a plastic overlay on a touchscreen due to ESD concerns. Screen was beyond a certain size (?) and non-dissipative. I looked all over for a high Z optically clear plastic. Needed to be ~ 2gohm/sq, IIRC. No joy. GE would make some if I bought a truckload (thanks!) - so would some others. We finally settled for no ATEX and no touch screen. If it was just a plastic part, colored, etc. I think we could have found a suitable replacement... John Linstrom Computer Dynamics ph 864.672.4363 x266 fx 864.675.0106 [email protected] -----Original Message----- From: Massey, Doug C. [mailto:[email protected]] Sent: Thursday, November 16, 2000 2:59 PM To: 'IEEE Forum' Subject: Intrinsically safe equipment Hello group - I'm looking for help regarding the safety of equipment for use in hazardous locations, especially intrisically safe systems. Specifically, I have questions regarding clause 7.3.2 of standard EN 50014:1997, concerning electrostatic charges of enclosures of plastic materials. If anyone has experience with the ATEX Directive standards (IEC-79 based), I would greatly appreciate hearing from you. Please e-mail me directly or call at (770) 447-4224 x3607. I'm afraid this discussion may get a little large for this forum, so I am hesitant to post detailed questions here to a group that may likely be uninterested in the topic. Thanks in advance. Doug Massey Safety Approvals Engineer LXE, Inc. Norcross, GA., USA Ph. (770) 447-4224 x3607 FAX (770) 447-6928 e-mail: [email protected] Cruise our website at: http:\\www.lxe.com ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
