Safety-related characteristics – KROHNE TT 51 SERIES EN User Manual
Page 18
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SAFETY-RELATED CHARACTERISTICS
18
TT 51 SERIES
www.krohne.com
09/2010 - 4000869801 - AD TT 51 SIL R01 en
Single TC + Single RTD 2/3w
Single TC + Single RTD 4w
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
146 535
41
94.3
2.09E-04
3.86E-04
9.20E-04
1.81E-03
4.10E-08
SIL 2
Close
coupled high
stress
0
146 3334
54
98.4
3.38E-04
5.72E-04
1.27E-03
2.45E-03
5.40E-08
SIL 2
Extension
wires low
stress
0
146 1853
50
97.5
2.83E-04
5.00E-04
1.15E-04
2.23E-03
5.00E-08
SIL 2
Extension
wires high
stress
0
146 29693
235
99.2
1.83E-03
2.85E-03
5.93E-03
1.10E-02
2.35E-07
(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
146 538
40
94.4
2.04E-04
3.77E-04
8.98E-04
1.76E-03
4.00E-08
SIL 2
Close
coupled high
stress
0
146 3381
48
98.6
3.10E-04
5.18E-04
1.14E-03
2.18E-03
4.80E-08
SIL 2
Extension
wires low
stress
0
146 1883
45
97.8
2.60E-04
4.55E-04
1.04E-03
2.02E-03
4.50E-08
SIL 2
Extension
wires high
stress
0
146 30283
145
99.5
1.42E-03
2.05E-03
3.93E-03
7.08E-03
1.45E-07
(SIL 2)
.book Page 18 Thursday, September 9, 2010 4:19 PM