BCU 480 · Edition 03.16l 76
Technical data
9.3 Safety-specific characteristic values
In the case of ionization control,
suitable for Safety Integrity Level
SIL 3
Diagnostic coverage DC 92.7%
Type of subsystem Type B to EN 615082, 7.4.3.1.4
Mode of operation
High demand mode pursuant to EN
615084, 3.5.12
Mean probability of dangerous
failure PFH
D
1.92 x 10
8
1/h
Mean time to dangerous failure
MTTF
d
MTTF
d
= 1 / PFH
D
Safe failure fraction SFF 98.8%
The specified values apply for the combination with
ionization electrode (sensor) and a unit of the BCU 400
series. No characteristic values are available for flame
control with UVS sensor.
For flame control with UVD sensor, safety-specific
characteristic values are available for the Safety Integ-
rity Level SIL. Further information can be found in
TI UVD 1 at www.docuthek.com.
Relationship between the Performance Level (PL)
and the Safety Integrity Level (SIL)
PL SIL
a –
b 1
c 1
d 2
e 3
Pursuant to EN ISO 138491:2006, Table 4, the BCU
can be used up to PL e.
Max. service life under operating conditions: 20 years
after date of production.
For a glossary of terms, see page 79 (Glossary).
For further information on SIL/PL, see www.k-sil.de
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