Converting Units; Safety-Specific Characteristic Values For Sil; And Pl - Honeywell BCU 460 Technical Information

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