ABB Endura AZ20 - Zirconia probe as part of the safety function system

ENDURA AZ20 & AZ30 | OXYGEN ANALYZER | SI/AZ20/AZ30-EN REV. A
5
4 Other applicable documents and
papers
Table 2 AZ20 reference documents
Data Sheet
Endura AZ20 oxygen analyser
Combustion Gas Analysis
DS/AZ20-EN
Maintenance Guide
Endura AZ20 oxygen analyser
Combustion Gas Analysis
IM/AZ20M-EN
User Guide
Endura AZ20 oxygen analyser
Combustion Gas Analysis
IM/AZ20P-EN
Manual
Endura AZ20 oxygen analyser
Combustion Gas Analysis
IM/AZ20E-EN
Table 3 AZ30 reference documents
Data Sheet
Endura AZ30 oxygen analyser
Combustion Gas Analysis
DS/AZ30-EN
Maintenance Guide
Endura AZ30 oxygen analyser
Combustion Gas Analysis
MI/AZ30M-EN
User Guide
Endura AZ30 oxygen analyser
Combustion Gas Analysis
OI/AZ30P-EN
Programming Guide
Endura AZ30 oxygen analyser
Combustion Gas Analysis
COI/AZ30E-EN
5 Zirconia probe as part of the
safety function system
The AZ20 or AZ30 transmitter generates an analog signal (4 to
20 mA) proportional to the oxygen % content. The analog signal
is fed to a downstream logics unit such as a PLC or a limit signal
generator, and is monitored for exceeding a specified
maximum or minimum value.
The following elements of the detector are considered to be
within the boundary of the safety system covered in this
manual:
• AZ20 or AZ30 probe
• AZ20 or AZ30 transmitter
• Interconnecting cable (only applicable to remote transmitter
versions)
The safe operation of anything else beyond the above
components falls outside the scope of this document.
Note:
HART is not considered part of the SIL output
Device-specific data related to functional
safety
Table 4 Device-specific data
Device type AZ20 oxygen analyzer
AZ30 oxygen analyzer
Type of assessment IEC61508
Hardware type tolerance 0
Component type B
Failure rates
Table 5 Failure rates
High demand Low demand
Safety integrity SIL 1 SIL 2
“hazardous” failure
(revealed)
0.28 10
-2
per annum 3.11 10
-6
per hour
“hazardous” failure
(unrevealed)
2.72 10
-2
per annum 3.22 10
-7
per hour
“safe” failure
(revealed)
0 0.54 10
-6
per hour
“safe” failure
(unrevealed)
0 0
Diagnostic coverage >91 % 90.6 %
Safe failure fraction >91 %
Probability of failure
on demand
1.6 10
-3