BS EN 61511-3:2017 provides information on:
- the underlying concepts of risk and the relationship of risk to safety integrity (see Clause
A.4);
- the determination of tolerable risk (see Annex K);
- a number of different methods that enable the safety integrity level (SIL) for the safety
instrumented functions (SIF) to be determined (see Annexes B through K);
- the impact of multiple safety systems on calculations determining the ability to achieve the
desired risk reduction (see Annex J).
In particular, this part of IEC 61511:
- a) applies when functional safety is achieved using one or more SIF for the protection of
either personnel, the general public, or the environment;
- b) may be applied in non-safety applications such as asset protection;
- c) illustrates typical hazard and risk assessment methods that may be carried out to define
the safety functional requirements and SIL of each SIF;
- d) illustrates techniques/measures available for determining the required SIL;
- e) provides a framework for establishing SIL but does not specify the SIL required for specific
applications;
- f) does not give examples of determining the requirements for other methods of risk
reduction.
NOTE Examples given in the Annexes of this Standard are intended only as case specific examples of
implementing IEC 61511 requirements in a specific instance, and the user should satisfy themselves that the
chosen methods and techniques are appropriate to their situation.
Annexes B through K illustrate quantitative and qualitative approaches and have been
simplified in order to illustrate the underlying principles. These annexes have been included to
illustrate the general principles of a number of methods but do not provide a definitive
account.
NOTE 1 Those intending to apply the methods indicated in these annexes can consult the source material
referenced in each annex.
NOTE 2 The methods of SIL determination included in Part 3 may not be suitable for all applications. In particular,
specific techniques or additional factors that are not illustrated may be required for high demand or continuous
mode of operation.
NOTE 3 The methods as illustrated herein may result in non-conservative results when they are used beyond
their underlying limits and when factors such as common cause, fault tolerance, holistic considerations of the
application, lack of experience with the method being used, independence of the protection layers, etc., are not
properly considered. See Annex J.
Figure 2 gives an overview of typical protection layers and risk reduction means.
Cross References:IEC 61511-2:2016
EN 61511-1 (IEC 61511-1:2003) AS ISA-S91.00.01
VDI/VDE 2180:2015
CEN ISO/TR 12489 (ISO/TR 12489:2013)AS
IEC TS 62556:2014
EN 61025 (IEC 61025:2006) AS
EN 61165 (IEC 61165:2006) AS
ISO/TR 12489:2013 ED1
IEC 61882:2001
IEC 61508-5:2010 Ed 2
EN 61508-6 (IEC 61508-6:2010) AS
IEC 61508-6:2010
IEC 61165:2006
IEC 61025:2006
IEC 62551:2012
EN 61508-5 (IEC 61508-5:2010) AS
EN 62551 (IEC 62551:2012) AS
All current amendments available at time of purchase are included with the purchase of this document. | File Size : | 1
file
, 6.3 MB |
| ISBN(s) : | 9780580791253 |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 106 |
| Product Code(s) : | 30264233, 30264233 |
| Published : | 05/22/2017 |
