<A2. SAFETY INSTRUMENTED SYSTEMS INSTALLATION>
A2-5
IM 01R01B02-00E-E 12th edition October 01, 2014 -00
All Rights Reserved. Copyright © 2003, Rota Yokogawa
A2.4 Assessment results
A2.4.1 Safety related parameters
The following results have been obtained from the assessment report Report No.: ROTA YOKOGAWA 05/04-
20 R001 Version V4, 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 A2.2: Summary for RAMC ([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)
143 FIT
197 FIT
Fail Dangerous Detected (
λ
DD)
0 FIT
0 FIT
Fail Dangerous Undetected (
λ
DU)
55 FIT
94 FIT
SFF
4
72.4%
67.8%
MTBF
528 years
349 years
SIL AC
5
SIL2
SIL2
Safety metrics according to ISO 13849-1
6
:
MTTF
d
(years)
2076
1214
DC
0%
0%
Category (CAT)
CAT 1
CAT 1
Performance Level (required)
PL
r
= c
PL
r
= c
Performance Level (calculated)
5.50E-08 1/h
9.40E-08 1/h
T[Proof] = 1 year
T[Proof] = 5 years
T[Proof] = 10 years
PFDAVG = 2.63E-04
PFDAVG = 1.22E-03
PFDAVG = 2.41E-03
Table A2.3: Summary for RAMC ([V1]) with standard limit switches
7
– Failure rates
Profile 2
Profile 4
Fail Safe Detected (
λ
SD)
0 FIT
0 FIT
Fail Safe Undetected (
λ
SU)
174 FIT
228 FIT
Fail Dangerous Detected (
λ
DD)
0 FIT
0 FIT
Fail Dangerous Undetected (
λ
DU)
94 FIT
133 FIT
SFF
4
65.0%
63.2%
MTBF
400 years
288 years
SIL AC
5
SIL2
SIL2
Safety metrics according to ISO 13849-1
6
:
MTTF
d
(years)
1214
858
DC
0%
0%
Category (CAT)
CAT 1
CAT 1
Performance Level (required)
PL
r
= c
PL
r
= c
Performance Level (calculated)
9.40E-08 1/h
1.33E-07 1/h
T[Proof] = 1 year
T[Proof] = 5 years
T[Proof] = 10 years
PFDAVG = 4.49E-04
PFDAVG = 2.08E-03
PFDAVG = 4.12E-03
Summary of Contents for RAMC
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