NAMUR (German: Interessengemeinschaft Automatisierungstechnik der Prozessindustrie, the User Association of Automation Technology in Process Industries) is a German-founded but now international group of process-industry end users, including chemical, pharmaceutical, and oil and gas operators. It is deliberately not a standards body or an instrument vendor. NAMUR publishes recommendations (NE, short for NAMUR-Empfehlung) and worksheets (NA) that the automation world has quietly adopted as de facto standards.
For functional safety work, two NAMUR recommendations can be relevant, and most North American practitioners meet them on an instrument datasheet before they ever meet the name:
- NE 130 — “Selection of field devices for safety instrumented systems taking prior use into account” (Edition 2023-07-14): a user side selection and qualification methodology. Device selection and prior-use qualification, which feeds FMEDA inputs and prior-use justification on the data side of a PFD calculation.
- NE 43 — “Standardization of the Signal Level for the Failure Information of Digital Transmitters” (Edition 2021-07-26): a design standard that is the 4-20 mA fault-signaling convention, where an output of < 3.6 mA or > 21 mA , flags a device fault instead of a real reading. A manufacturer would state “meets NE 43” for example.
- Full texts are not free; they are obtained from the NAMUR Office or purchased through DIN Media.
Key Points
- NAMUR is a process-industry end-user association, not a standards body or vendor; its recommendations (NE) and worksheets (NA) are treated as de facto standards in process automation.
- Most North American automation/control engineers interface with the results of NAMUR although they may not know it, when they use the 3.6 mA or 21 mA rule established per NAMUR NE 43.
- A dedicated functional safety working group (WG 4.5) handles SIS topics; we at SIL Safe think NAMUR is worth knowing even for a US audience, since its conventions appear on nearly every European-built instrument you are likely to specify.
Example
A pressure transmitter on a SIF is specified as NAMUR NE 43 compliant. When its sensing element fails, the transmitter drives its output to 21.5 mA instead of holding a believable mid-scale value, so the logic solver reads the signal as a detected fault and takes the function to its safe state rather than trusting bad data.
Cited Sources
- NAMUR (User Association of Automation Technology in Process Industries), recommendations NE 43 and NE 130.
- NAMUR — official website
- NE 130
- NE 43