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<A1. SAFETY INSTRUMENTED SYSTEMS INSTALLATION>
A1-5
IM 01R01B30-00E-E 6th edition October 01, 2014 -00
All Rights Reserved. Copyright © 2003, Rota Yokogawa
A1.4 Assessment results
A1.4.1 Safety related parameters
The following results have been obtained from the assessment report Report No.: ROTA YOKOGAWA
08/07-23 R002
Version V2, Revision R1; August 2010 issued by exida.
Average PFD values have been calculated assuming a Diagnostic Coverage (DC) of 99%, a mission time
of 10 years and a Mean Time To Restoration of 24 hours.
Table 2: Summary for RAKD ([V1]) with fail-safe limit switches 3 – Failure rates
Profile 2
Profile 4
Fail Safe Detected (
λ
SD)
0 FIT
0 FIT
Fail Safe Undetected (
λ
SU)
132 FIT
174 FIT
Fail Dangerous Detected (
λ
DD)
4 FIT
19 FIT
Fail Dangerous Undetected (
λ
DU)
62 FIT
108 FIT
SFF
4
68.7%
64.1%
MTBF
486 years
310 years
SIL AC
5
SIL2
SIL2
Safety metrics according to ISO 13849-1
6
:
MTTF
d
(years)
1730
899
DC
6%
15%
Category (CAT)
CAT 1
CAT 1
Performance Level (required)
PL
r
= c
PL
r
= c
Performance Level (calculated)
6.60E-08 1/h
1.27E-07 1/h
T[Proof] = 1 year
T[Proof] = 5 years
T[Proof] = 10 years
PFDAVG = 2.96E-04
PFDAVG = 1.37E-03
PFDAVG = 2.72E-03