Probability & Failure Question

[jdhariwal]

Hi All,

I was wondering if someone could provide some input:

I have failure rates per million years for certain equipment.


How do I convert this to Probability Failure on Demand?

I know P = 1 - exp (-lambda x time), is this the correct formula to use?


Many thanks

J

[safetyuser]

I would say yes but this will be a simplistic reply not an engineering one, as equipment reliability is a wide matter. For example: electronic equipment failure would be better modelled by a Weibull or Lognormal statistical distribution rather than an exponential; exponential does not account for wear-out or early natality failure as well. However exponential is simple and well understandable by almost all engineers and if you have a very small lambda you also could add more simplification by using the approximation P = 0.5*lambda*time Let me suggest to have a good read of one of the books you can find on this matter, it could help more.