Safety-related Equipment
Yokogawa supplies safety-related elements like the safety P/dP transmitter EJX and the ProSafe family logic solvers. Recently, this family grew to accommodate the ProSafe-RS, safely integrated within the Centum-CS process automation system, but at the same time segregated from it so that the requirements of IEC 61508 are fully met.
EJX claims SIL 2 capability in single use, and SIL 3 in redundant safety architecture. ProSafe-RS claims SIL 3 even in single use. Can these claims be justified?
The EJX certificate gives, among others, the following information:
These figures are well-founded in the accompanying report and are sufficient for end- users, contractors and/or system integrators to define the SIL of the SIF in which they will be applied. The SFF justifies according IEC 61508, indeed SIL 2 capability in single use (PFDAVG calculation even higher) and SIL 3 in redundant architecture; so far it concerns the hardware safety integrity. What about its systematic safety integrity? The TÜV report states that our software and hardware development processes are on SIL 3 level. This justifies the SIL 3 claim for redundant safety architecture.
Does the SIL 3 claim for single ProSafe-RS conflict with the architectural constraints as per IEC 61508? No, because ProSafe-RS has built-in redundancy. Every module has double circuitry with 1oo2 voting and extended diagnostics. And not only the hardware has been examined – TÜV have thoroughly assessed the software and hardware development processes. In other words, systematic safety integrity also complies with the standards SIL 3 requires.
SIS Suppliers
Yokogawa is also supplier of safety solutions. As a system integrator it is responsible for either a part of a safety instrumented system (SIS) or for the complete SIS. To that end, it has organised its operations in such a way that it complies with the requirements for functional safety management (FSM) in accordance with both IEC 61508 and 61511. Two of its affiliates, being Yokogawa System Center Europe at Apeldoorn, The Netherlands, and Yokogawa East Asian’s Safety Center Asia at Kuala Lumpur, Malaysia, have been certified by TÜV Rheinland, TÜV Industrie Service GmbH, Automation, Software and Information Technology Certification Body for Functional Safety Management Systems.
A group of functional safety experts, independent from the operational groups that realise the systems, executes safety assessments on every safety system before shipment. This group also maintains the FSM by executing safety audits on a periodical base. As usual for quality systems, every year the certifying body executes a surveillance audit to confirm that the achieved level of systematic safe integrity is still being maintained.
Category:
Health & Safety
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