I never had a problem worse than nine cones of 24" pyramidal absorbers falling from 20 feet, so I never gave the hazard much thought. (And the failure mode then is that one corner lets go first, resulting in a rotational peel before the entire foam falls.) But a 96" long pyramid must have a base of maybe 24" x 24", and 80 pounds is impressive. It would fall fairly straight and even stabilize itself. Would the tip crush enough to decelerate the absorber very much? Even if it hit someone perfectly square on the head, would it crumple uniformly or just skid off one side of the head, maybe yielding a laceration or an abrasion? It would make for an interesting physics analysis.
Ed Price WB6WSN Chula Vista, CA USA From: Barron, Manny (IS) [mailto:[email protected]] Sent: Friday, January 10, 2014 3:29 PM To: [email protected] Subject: Re: [PSES] Risk Assessments and mitigation for EMC chambers Hi Ghery, Thanks for the clarification. I know you had it built, so you know the dimensions well. It is definitely a very large chamber, considering it had hundreds of 8 foot long RF absorbers within it. Regards, Manny Barron EMC/EMI Engineer Northrop Grumman Corp. San Jose, California From: Pettit, Ghery [mailto:[email protected]] Sent: Friday, January 10, 2014 3:21 PM To: Barron, Manny (IS); [email protected] Subject: EXT :RE: Risk Assessments and mitigation for EMC chambers Manny, That chamber was "only" 30 feet high, not 40 feet. J And Apple pulled all the absorbers out and re-lined it to make an antenna pattern chamber out of it. I understand their RF guys are tickled to have such a LARGE chamber for that work. I hope all is going well at Northrup Grumman for you. Ghery S. Pettit From: Barron, Manny (IS) [mailto:[email protected]] Sent: Friday, January 10, 2014 3:09 PM To: [email protected] Subject: Re: [PSES] Risk Assessments and mitigation for EMC chambers The main safety concern we had at our older 10m chamber (~15 years ago, previous employer) - was 80 lb polyurethane RF absorber cones falling from the 40 ft chamber ceiling. Had 3 cones fall over a 4 year period (in 3 separate events, different parts of ceiling), all fell overnight when nobody was around (found the cones on the floor the next morning). We all wondered if we could hear one fall and if we'd have time to see where it was falling from and have enough time to jump out of the way if necessary. Yeah it was scary, and it got everyone's attention, all the way up the management chain. After each cone fall event we had a contractor come in with a scissor lift to jiggle each ceiling cone to see if it was on the verge of coming loose (none were during those checks). After the 3rd cone fall we had a contractor install a thick netting (nylon I think) over the entire ceiling up near the ceiling level. It probably wouldn't stop the 80 lb cone from hitting the floor, but it would definitely delay it (hopefully providing some warning). About a year after the net installation the entire lab was shut down (closed due to massive company layoff). Escape from danger! Whenever I walk into a room, even today, I tend to look up at the ceiling suspiciously. Manny Barron EMC/EMI Engineer Northrop Grumman Corp. San Jose, California From: Charlie Blackham [mailto:[email protected]] Sent: Thursday, January 09, 2014 12:39 PM To: [email protected] Subject: EXT :[PSES] Risk Assessments and mitigation for EMC chambers All Client has performed risk assessment for turntables and high RF fields in their anechoic chambers and is looking at implementing emergency stops for the former and flashing lights warning of the later. (I've never seen flashing lights at other labs whilst witnessing tests up to 350 V/m, and the client chamber will only be used with amps < 250 W). The turntable is not flush to the floor, so does present more hazard than some, and some operation does require people to be on or adjacent to the turntable for operation/maintenance. There is already plenty of good "process" and supporting documentation and everyone with access to the chambers have already been through a thorough safety briefing. Anyone have any documents or stories to share as to how they have satisfied/pacified/dismissed enthusiastic Health & Safety officers who still want to "do something"? Regards Charlie Charlie Blackham Sulis Consultants Ltd Tel: +44 (0)7946 624317 Web: www.sulisconsultants.com <http://www.sulisconsultants.com/> Registered in England and Wales, number 05466247 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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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: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) <http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- 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: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) <http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- 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: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
