>-----Original Message----- >From: Rich Nute [mailto:ri...@sdd.hp.com] >Sent: Friday, January 31, 2003 4:17 PM >To: j...@jmwa.demon.co.uk >Cc: emc-p...@majordomo.ieee.org >Subject: Re: single fault conditions > > > > > > >Hi John: > > >> >For example, at a previous employer, I observed several >instances of FETs >> >(in a 3kVA instrument) exploding and sending molten metal >(mostly from the >> >leads and the lead's solder pads) through chassis vents, >that subsequently >> >caused the surrounding cheesecloth to ignite. >> >> WOW! I wouldn't have though that there would be enough >energy in the >> droplets after their flight through the air to cause >ignition. Did you >> treat the cheesecloth with potassium nitrate solution >before the test? > >Molten metal has: > > high temperature > high stored energy > high thermal conductivity > >A small drop (1-2 mm diameter) of molten >copper falling through about 0.4 meter >will ignite non-flame-retardant plastic >material (I've done the test and have the >pix). > >Very much smaller pieces would ignite >unalduterated cheesecloth. > > >Best regards, >Rich
Rich: I first performed this test in 1965, albeit with certain modifications. I applied a molten glob of 60/40 alloy solder, through a 0.5 meter fall from a soldering iron, into the interstitial space between my leather shoe and Orlon sock. I did not experience synthetic fabric ignition, but I certainly did achieve lift-off (as I hopped around the lab trying to rip off my boot). In addition to pioneering this test method, I also think I invented disco that day. Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
