FLAMMABLE GAS SENSOR/TRANSMITTER
A T E X
M1
GROUP I & II
INTRINSICALLY
SAFE
25/28
INSTALLATION & OPERATING DATA
11 FUNCTIONAL SAFETY
11.2
Overview of Safety Integrity Level
The following instructions are applicable when the TX6383 Flammable Gas
Sensor/Transmitter is used as an element in a safety instrumented function that is
specified to achieve a Safety Integrity Level (SIL), eg. SIL 1, 2, etc.
The reliability of the TX6383 Flammable Gas Sensor/Transmitter has been
independently assessed in accordance with IEC 61508 for use in SIL applications. The
compliance with IEC 61508 includes hardware reliability (probabilistic type failures)
and measures to address systematic type failures.
The information that follows forms the 'Safety Manual' required by IEC 61508-2 and
is intended to allow correct product selection, system integration, installation,
operation and maintenance to enable the SIL specified for the safety instrumented
function to be achieved and maintained, as far as the TX6383 Flammable Gas
Sensor/Transmitter is concerned.
The actual SIL will depend on many system considerations that are outside the scope
of the TX6383 Flammable Gas Sensor/Transmitter and will rely on personnel who are
competent in the functional safety aspects of the various lifecycle activities
mentioned above.
SIL Suitability
The versions and configurations of the TX6383 Flammable Gas Sensor/Transmitter
identified in Table 1 in Section 11.3 below and are suitable for use in gas detection
safety functions that have a specified Safety Integrity Level (SIL) in accordance with
IEC 61508 or IEC 61511 up to and including:
SIL 2
- when used in a 'Low Demand' safety function
[1]
SIL 1
- when used in a 'High Demand' safety function
[1]
The functional safety data in Tables 1 and 2 in Section 11.3 must be taken into
account by integrators and end-users, including compliance with the restrictions in
use (Section 11.4) and all other provisions and conditions in this manual.
System integrators and end users responsible for other lifecycle phases (system
specification, integration, installation, commissioning, operation, maintenance, etc)
need to perform assessments on the complete scope of their activities to ensure a
target SIL for the safety function is and continues to be met.
[1]
Low Demand and High Demand modes of operation are defined in IEC 61508-4, 3.5.16
11.1
TT X
X 66 33 88 33
ISSUE S 01/15
