NE 146 has been revisedfrom 2021-05-06
This document differs from NE 146: 2013-10-21 as follows:
- Separate German and English versions
- Normative references updated
- Definitions and terms updated and added
- Figure 1, Workflow of planning, evaluation and field testing extended
- Figure 2 revised
- Table 1, Minimum hardware fault tolerance updated
- Examples added
- Approach to determining common cause failures added
- Former sections 126.96.36.199 IEC 61508-based determination, 188.8.131.52 Markov model-based determination, 184.108.40.206 Cluster approach deleted
- Mathematical formulae in Annex C reviewed and corrected
- Editorial changes
Abstract NE 146 ‘Process analyser technology systems as part of safety instrumented systems’
PAT measuring equipment is used, for example, in process industry as sensor components of safety instrumented systems. In many cases it represents the only or most efficient method for monitoring a process variable which, for its part, enables a reliable evaluation of designated use of the system to be protected. Due to the direct material interaction with the process medium, PAT measuring equipment is in general more susceptible to failure than the sensors widely used for pressure, temperature, level and flow.
NE 146 addresses already existing experiences from PAT measuring equipment as part of safety instrumented systems and relates them directly to characteristics of existing standards. It is designed to aid users at planning, installation and operation of PAT measuring equipment as part of safety instrumented systems.