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   On 2024-12-09, The Natural Philosopher  wrote:   
   >> https://www.rs-online.com/designspark/why-l10-life-expectancy   
   is-key-for-fan-durability-over-mtbf-ratings   
   >   
   > This is full of bullshit   
   >   
   > "MTBF estimates the lifespan of a fan’s electronic components, expressed   
   > in millions of hours. In contrast, L10 Service Life, measured in   
   > thousands of hours, is based on the durability of the bearings and   
   > lubrication grease."   
   >   
   > So a fan with no electronic components has no MTBF?   
      
   remove "electronic" and it makes sense.   
      
   >> https://www.digi.com/support/knowledge-base/understanding-mtb   
   -mean-time-between-failures   
   >>   
   >   
   >   
   > "Furthermore, MTBF specifically excludes wear-out factors"   
   >   
   >   
   >   Total crap.   
      
   No. Again, MTBF characterizes failures during normal service life.   
      
   Take a fan which usually fails after 5 years of operation due to wearout,   
   which happens on all of those fans after about the same amount of time -   
   those 5 years are *not* parts of the MTBF.  MTBF characterizes the   
   statistical mean time between failures *during* those 5 years due to *other*   
   reasons.   
      
   So you can have a MTBF of 50 years, and a lifetime of 5 years. If you take   
   100 of those fans, you can expect 2 failures per year - but after 5 years,   
   the failure rate will rise rapidly to reach 100%.   
      
   > What matters is how long the repair or the new fan will last. Not   
   > splitting hairs over MTTF versus MTBF   
      
   The important thing is to keep MTBF and lifetime separate - both will lead   
   to failures, but are separate mechanisms.   
      
   cu   
   Michael   
   --   
   Some people have no respect of age unless it is bottled.   
      
   --- SoupGate-Win32 v1.05   
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