Hello Moshe, Few vendors will give out anything more than L10 ratings. Their testing isn't designed to give much more. You can generally assume that the failure rate will start to increase significantly shortly after the L10 life. The bearings are often the limiting factor. The problem is that you never know fast the failure rate increases. I have seen fans where there is a linear failure rate through the L10 life and well beyond, and others that start having significant failures shortly after the L10 life. You need to keep asking your vendors for this information.
These web sites may give some help in calculating life for bearings. http://www.pacamor.com/technical/lifeandload.ssi2.php http://www.epi-eng.com/BAS-BearingLife.htm The calculations can get more complicated for variable speed fans. Ted Eckert American Power Conversion/MGE http://www.apc.com/ The items contained in this e-mail reflect the personal opinions of the writer and are only provided for the assistance of the reader. The writer is not speaking in an official capacity for APC-MGE or Schneider Electric. The speaker does not represent APC-MGE's or Schneider Electric's official position on any matter. Moshe Valdman <mvaldman@netvisi on.net.il> To Sent by: "'EMC PSTC'" <[email protected]> [email protected] cc Subject 03/26/2008 11:42 Life expectancy of fans AM Hi all, I'm having problems getting weibull parameters from DC fan manufacturers They give L10 (useful life - time when 10% of fans have died) but not the beta (shape factor) I.e. I can't know how quickly the rest of the 90% will fail Can anyone help on this? thanks in advance, Moshe Valdman - reliability engineer - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.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] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
