Honeywell BCU 465 - Safety Characteristic Values for SIL and PL

BCU 460, BCU 465 · Edition 11.19 136
Converting units
18 Converting units
See www.adlatus.org
19 Safety-specific characteristic values for SIL
and PL
Certificates – see Docuthek.
For systems up to SIL 3 pursuant to EN 61508.
Pursuant to EN ISO 13849-1:2006, the BCU can be
used up to PLe.
Suitable for Safety Integrity Level Up to SIL 3
Diagnostic coverage DC 91.3%
Type of subsystem Type B to EN 61508-2:2010
Mode of operation
High demand mode pursuant to EN
61508-4:2010
Mean probability of dangerous
failure PFH
D
32.9 × 10
-9
1/h on BCU 4xx..F1,
38.3 × 10
-9
1/h on BCU 4xx..F3
Mean time to dangerous failure
MTTF
d
MTTF
d
= 1/PFH
D
Safe failure fraction SFF 99.0%
Mean probability of dangerous failure PFH
D
of
individual safety functions
Burner control with 2 gas valves 23.2 × 10
-9
1/h
Burner control with 3 gas valves 28.5 × 10
-9
1/h
Valve check 15.0 × 10
-9
1/h
Proof of closure 3.3 × 10
-9
1/h
Flame control 8.4 × 10
-9
1/h
Temperature monitoring 2.2 × 10
-9
1/h
Air pressure switch monitoring 3.3 × 10
-9
1/h
Gas pressure switch monitoring 3.3 × 10
-9
1/h
Purge with air pressure switch 4.3 × 10
-9
1/h
K-SafetyLink 1.0 × 10
-9
1/h
Safety interlocks (limits) 2.2 × 10
-9
1/h
Valve check with redundant pressure switch 12.9 × 10
-9
1/h
Air pressure switch monitoring with red. pressure switch 1.3 × 10
-9
1/h
Gas pressure switch monitoring with red. pressure switch 1.3 × 10
-9
1/h
Purge with red. air pressure switch 2.3 × 10
-9
1/h
Relationship between the Performance Level (PL)
and the Safety Integrity Level (SIL)
PL SIL
a –
b 1
c 1
d 2
e 3
Max. service life under operating conditions:
10 years after date of production.
For a glossary of terms, see page141 (Glossary).