[SystemSafety] Units for Functional Safety variables ? - A Friday afternoon question on a Wednesday.

From: Jon Hind < >
Date: Wed, 2 Oct 2013 15:49:23 +0100

I posted this (only partially) frivolous question on out internal system, without any reply.

So trying here for some erudition...

What dimension and or units does Hardware Fault Tolerance (HFT) have ? - A Friday Poser on Functional Safety Terminology (FST).

I remember being taught at university in the last century that everything has a dimension in terms of Length (L) , Mass (M) and or Time (T), or is a ratio (factor). A good check of the validity of an equation is that it must balance dimensionally.

Availability Common Cause Factor (, CCF) and Safe Failure Fractions (SFF) are dimensionless ratios, failures rates () are T^-1, Proof Test intervals are T etc.

And HFT ? HFT is an integer - In our (oil & gas process) world, 0 1 or 2 ; is it part of a case statement, or heaven forbid a pointer like in the C language ?

I don't want to call it a factor as we already have that in CCF and SFF.

Answers on a postcard please....

Jon Hind

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systemsafety_at_xxxxxx Received on Wed Oct 02 2013 - 16:49:52 CEST

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