The safety manual is a document required for any system or product certified in accordance with IEC 61508: 2 “Functional safety of electrical, electronic and programmable electronic systems for safety applications”, where the safety manual is a mandatory document that the manufacturer must enclose to any SIL device.
Definition and table of contents of a Safety Manual
The safety manual is a document designed to provide all relevant information on Functional Safety with the aim of maintaining the reliability and the safety performance of the device over time. Therefore, the safety manual has a fundamental importance, since it constitutes, together with the Functional safety Assessment report, the documentation that certifies the conformity of a product with the IEC 61508: 1-7 standard, as well as the SIL level that can be reached.
The regulatory references for a safety manual can be found in Appendix D of 61508-2.
The safety manual table of contents must refer to:
- The identification of the supported versions of the product and the necessary skills required to the operator for using a certain device
- A clear description of the safety functions that can be performed together with the related input / output interfaces
- Special instructions and limitations for configuring the product for safety applications
- Limitations on the use of the compliant product and / or assumptions on which the analysis of behavior and reliability parameters are based
- Random (hardware) failure rates, classified either as safe / dangerous or detected / undetected.
- Hardware fault tolerance and type of product (A or B)
- The value of Systematic capability (on a scale from 1 to 4) including the procedures that had been followed during the realization of the product in order to prevent systematic failures
- Requirements and procedures for the maintenance of the product
- Requirements, times and procedures for the execution of the Proof Test, which is the complete and voluntary execution of the safety function that highlights potential failures of a SIS, that could compromise the whole safety of the system
- Indications on other possible external diagnostic solutions that could be implemented on a system.
What the safety manual is for
The safety manual gathers in a single document all the helpful information to let an end user safely integrate a component (or a complex component) into an instrumented safety system. Furthermore, any device that is not accompanied by the manual does not comply with the minimum requirements applicable to any SIL level dictated by the IEC 61508, as well as required by other related application standards (i.e. EN 62061 and EN 61511, ISO 26262 and so on).
The table of contents of the safety manual reveals its importance as a closing element of the certification process. All the information and data on the reliability and safety parameters, that are reported therein, derive from the technical documentation drawn up during the SIL certification process (for example FMEDA analysis or the Systematic Capability analysis). In conclusion, only in the presence of a safety manual is it possible to ensure product compliance.
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