KROHNE TT 51 SERIES EN - Manual (Page 16)

7
SAFETY-RELATED CHARACTERISTICS
16
TT 51 SERIES
www.krohne.com 09/2010 - 4000869801 - AD TT 51 SIL R01 en
Single RTD 4w sensor
Dual RTD 4w sensor with activated sensor drift monitoring (only for TT 51 R SIL versions); in
preparation
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
0 146 436 43 93.1 2.16E-04 4.02E-04 9.62E-04 1.89E-03 4.30E-08 SIL 2
Close
coupled high
stress
0 146 1338 90 94.2 4.62E-04 8.52E-04 2.02E-03 3.97E-03 9.00E-08 (SIL 2)
Extension
wires low
stress
0 146 883 45 95.8 2.36E-04 4.31E-04 1.024E-03 1.99E-03 4.50E-08 SIL 2
Extension
wires high
stress
0 146 10288 140 98.6 9.15E-04 1.52E-03 3.34E-03 6.38E-03 1.40E-07 (SIL 2)
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
Close
coupled high
stress
0
Extension
wires low
stress
0
Extension
wires high
stress
0
.book Page 16 Thursday, September 9, 2010 4:19 PM