Endress+Hauser Liquiphant S FDL60 - Functional Safety Figures

Liquiphant S, Nivotester
8 Endress+Hauser
Functional safety figures The table shows the specific figures for functional safety for Liquiphant S + FEL67 + Nivotester FTL670:
Dangerous undetected failures in this scenario:
A dangerous, undetected failure is defined as an incorrect output signal where the tuning fork is covered while
the fail-safe contact is closed.3
Useful lifetime of electrical components:
The established failure rates of electrical components apply within the useful lifetime as per IEC 61508-2,
Section 7.4.7.4. Note 3.
Figures
according to IEC 61508
Value
Liquiphant S + FEL67 Nivotester FTL670 Liquiphant S + FEL67
+ Nivotester FTL670
Safety function MAX Level
SIL 3
HFT 1
Device type B
Mode of operation Low demand mode, High demand mode
SFF 91.4 % 90.1 % 91 %
MTTR 8 h
Recommended
proof-test interval T
1
15 years
λ
sd
*
2
401.4 FIT 179.5 FIT
λ
su
*
2
83.4 FIT 44.5 FIT
λ
dd
*
2
401.4 FIT 179.5 FIT
λ
du
*
2
83.4 FIT 44.5 FIT
λ
tot
*
2
969.5 FIT 447.9 FIT 1417.4 FIT
β 5 % 5 % -
β
D
2 % 2 % -
PFD
avg
for T
1
= 15 years *
1
1.73 × 10
-4
9.24 × 10
-5
2.66 × 10
-4
PFH for T
1
= 15 years *
1
2.64 × 10
-9
1.41 × 10
-9
4.04 × 10
-9
MTBF *
3
117 years 254 years 80 years
Diagnostic test interval *
4
30 s
Fault reaction time *
5
3 s
System reaction time *
6
0.5 s with tuning fork covered
1.0 s with tuning fork uncovered
*
1
The values correspond to SIL 3 as per ISA S84.01.
*
2
According to Siemens SN29500.
*
3
According to Siemens SN29500, including faults outside of the safety function.
*
4
During this time, all diagnostic functions are executed at least once.
*
5
Time between fault detection and fault reaction.
*
6
Step response time as per DIN EN 61298-2.