Instruction Manual Supplement
D103401X012
ED, ES, ET, EW, EZ, HP Valves
November 2017
3
Acronyms
FMEDA:
Failure Modes, Effects and Diagnostic Analysis
HFT:
Hardware Fault Tolerance
MOC:
Management of Change. These are specific procedures often done when performing any work activities in
compliance with government regulatory authorities.
PFD
AVG
:
Average Probability of Failure on Demand
SFF:
Safe Failure Fraction, the fraction of the overall failure rate of a device that results in either a safe fault or a
diagnosed unsafe fault.
SIF:
Safety Instrumented Function, a set of equipment intended to reduce the risk due to a specific hazard (a safety
loop).
SIL:
Safety Integrity Level, discrete level (one out of a possible four) for specifying the safety integrity requirements of
the safety functions to be allocated to the E/E/PE safetyrelated systems where Safety Integrity Level 4 has the highest
level of safety integrity and Safety Integrity Level 1 has the lowest.
SIS:
Safety Instrumented System – Implementation of one or more Safety Instrumented Functions. A SIS is composed
of any combination of sensor(s), logic solver(s), and final element(s).
