User Manual

5.1 95-86307
TERMS AND DEFINITIONS
AMS Asset Management System
DU Dangerous Undetected
FMEDA Failure Mode Effects and Diagnostics
Analysis
HART HighwayAddressableRemoteTransducer
HFT HardwareFaultTolerance
LFL Lower Flammable Limit
PFD Probability of Failure on Demand
(Probability of Dangerous Failure)
PFDavg Average Probability of Failure on Demand
PIRECL Pointwatch Eclipse
®
IR Gas Detector
SFF Safe Failure Fraction
SIF Safety Instrumented Function
SIL Safety Integrity Level
SIS Safety Instrumented System
UD20 FlexVu
®
Model UD20 Universal Display
IEC 61508 Failure Rates in FIT
1
Failure Category
lsd lsu
2
ldd ldu
SFF
3
PIRECL IR Gas Detector, Analog Output 0 46 1655 123 93.3
PIRECL IR Gas Detector, Relay Output 106 222 1335 130 92.7
PIRECL IR Gas Detector with UD20 Universal Display,
Analog Output
0 46 1691 142 92.5
PIRECL IR Gas Detector with UD20 Universal Display,
Relay Output
106 222 1371 149 91.9
1
FIT = 1 Failure / 10
9
Hours
2
It is important to realize that the No Effect failures are no longer included in the Safe Undetected Failure category according to IEC 61508,
ed2, 2010.
3
Safe Failure Fraction needs to be calculated on (sub)system level.