Hi James:
The UL94 flammability ratings are based on standardized samples of the plastic material. The ratings may or may not be representative of the results in the end-product. My suggestion is to do the UL94 test on the whole end-product. The heat-sinking of the internal components may allow the enclosure to meet the V-1 requirement. (Many years ago, I did this (passed) on a populated PC board, where the unpopulated board was rated HB.) A second suggestion: Consider that the battery is the source of the flame. Use a fire starter pill/tablet inside the device to ignite the enclosure (you have to quickly put the enclosure back together). The device probably doesn't have enough oxygen inside to sustain flaming sufficient to ignite the enclosure. If you burn a hole in the enclosure (which allows the flaming to attack the outside surface), you will likely fail the test. Good luck! Rich From: James Pawson (U3C) <[email protected]> Sent: Friday, May 31, 2024 8:43 AM To: [email protected] Subject: [PSES] Li-Ion Fire Enclosure (IEC 62368-1:2018 / EN 62368-1:2020) Concept Hi folks, We are working with a client on a small wearable device with a PS2 Li-Ion cell. Annex M.4.3 requires a fire enclosure for the PS2 capable battery. The plastic the client wants to use is not datasheet rated to UL 94 V-1 in the thickness they are using (testing could be performed to establish this) We are investigating the attached construction (also <https://unit3compliancecouk-my.sharepoint.com/:i:/g/personal/james_unit3com pliance_co_uk/EYDdhd6tpK1InDtDFOTVb4UB_KRHzF9nFOhPlI-RX7TLgA?e=QfhWw0> here) and I was looking for a sanity check to see if I was missing anything. * Plastic case rated between HB40 and V-2 (6.3.1 for materials outside a fire enclosure). Mechanically robust for drop test. * PS2 battery with metal foil wrap (e.g. thick aluminium self adhesive tape with no gaps other than cable egress) meeting fire enclosure requirements in 6.4.8.2.2 (no material thickness specified) * PS2 PCB circuit relies on reduce likelihood of ignition proved by single fault testing * VW-1 rated cable I feel like I'm missing something important. Thoughts and comments appreciated. All the best James James Pawson Managing Director & EMC Problem Solver Unit 3 Compliance Ltd EMC : Environmental & Vibration : Electrical Safety : CE & UKCA : Consultancy <http://www.unit3compliance.co.uk/> www.unit3compliance.co.uk | <mailto:[email protected]> [email protected] +44(0)1274 911747 | +44(0)7811 139957 2 Wellington Business Park, New Lane, Bradford, BD4 8AL Registered in England and Wales # 10574298 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to [email protected] All emc-pstc postings are archived and searchable on the web at: https://www.mail-archive.com/[email protected]/ Website: https://ewh.ieee.org/soc/pses/ Instructions: https://ewh.ieee.org/soc/pses/list.html (including how to unsubscribe) List rules: https://ewh.ieee.org/soc/pses/listrules.html For help, send mail to the list administrators: Mike Sherman at: [email protected] Rick Linford at: [email protected] For policy questions, send mail to: Jim Bacher: <[email protected]> _________________________________________________ To unsubscribe from the EMC-PSTC list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=EMC-PSTC&A=1
