Safety-related characteristics – KROHNE TT 51 SERIES EN User Manual
Page 15
SAFETY-RELATED CHARACTERISTICS
7
15
TT 51 SERIES
www.krohne.com
09/2010 - 4000869801 - AD TT 51 SIL R01 en
Single RTD 2/3w sensor
Dual RTD 3w sensor with activated sensor drift monitoring
Failure category
SFF PFD
avg
at T
proof
=
PFH
SIL AC
λ
SD
λ
SU
λ
DD
λ
DU
[FIT]
[%]
1 year
2 years
5 years
10 years
Close
coupled low
stress
0
146 427
49
92.1
2.44E-04
4.57E-04
1.09E-03
2.16E-03
4.90E-08
SIL 2
Close
coupled high
stress
0
146 1175 213
86.1
1.05E-03
1.97E-03
4.74E-03
9.36E-03
2.13E-07
(SIL 2)
Extension
wires low
stress
0
146 768
135
87.1
6.63E-04
1.25E-03
3.00E-03
5.93E-03
1.35E-07
(SIL 2)
Extension
wires high
stress
0
146 7988 1940 80.7
9.45E-03
1.79E-02
4.31E-02
8.52E-02
1.94E-06
(SIL 1)
The boxes marked in light grey in the following tables mean that the calculated PFD
avg
and/or
PFH values are within the allowed range for SIL 2 according to table 2 / 3 of IEC 61508-1 but do not
fulfill the requirement to not claim more than 35% of this range, i.e. to be better than or equal to
3.50E-03 respectively 3.50E-07 1/h.
The boxes marked in medium grey mean that the calculated PFD
avg
and PFH values are within the
allowed range for SIL 2 according to table 2 / 3 of IEC 61508-1 and do fulfill the requirement to not
claim more than 35% of this range, i.e. to be better than or equal to 3.50E-03 respectively
3.50E-07 1/h.
The boxes marked in dark grey indicate that the PFD
avg
respectively the PFH values do not fulfill
the requirements for SIL 2 of table 2 / 3 of IEC 61508-1.
Failure category
SFF PFD
avg
at T
proof
=
PFH
SIL AC
λ
SD
λ
SU
λ
DD
λ
DU
[FIT]
[%]
1 year
2 years
5 years
10 years
Close
coupled low
stress
0
146 483
41
93.9
2.07E-04
3.85E-04
9.18E-04
1.81E-03
4.10E-08
SIL 2
Close
coupled high
stress
0
146 2291
57
97.7
3.27E-04
5.74E-04
1.35E-03
2.55E-03
5.70E-08
SIL 2
Extension
wires low
stress
0
146 1329
50
96.7
2.71E-04
4.87E-04
1.14E-03
2.22E-03
5.00E-08
SIL 2
Extension
wires high
stress
0
146 19198
230
98.8
1.56E-03
2.56E-03
5.55E-03
1.05E-02
2.30E-07
(SIL 1)
.book Page 15 Thursday, September 9, 2010 4:19 PM