Glossary Updates12 new terms added to the glossaries · October 2, 2026, 22:44 CEST
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Glossary · Process instrumentation and analytical measurement

Ex i protection

Also known as: Type of protection intrinsic safety, Ex i

German: Zündschutzart Ex i

In explosion protection, Ex i is the type of protection intrinsic safety, which limits the electrical and thermal energy in circuits so that neither sparks nor hot surfaces can ignite an explosive atmosphere. It is specified in IEC 60079-11 with the levels of protection ia, ib and ic.

  • Process instrumentation
  • Standards
  • Process industry

In one sentence

Ex i is the type of protection intrinsic safety per IEC 60079-11, limiting energy so circuits cannot ignite an explosive atmosphere.

Example

A pressure transmitter marked Ex ia IIC T4 Ga can be installed in zone 0, connected through an associated apparatus such as an isolating barrier.

How it applies

  • Engineering: The level of protection ia is suitable for zone 0 and zone 20, ib for zone 1, ic for zone 2, subject to the equipment protection level required for the area. The marking also shows the gas group and temperature class.
  • Installation: The field device alone is not enough: the whole circuit, including associated apparatus, cables and their capacitance and inductance, must be assessed. IEC 60079-14 covers installation.
  • Maintenance: Ex i allows some work on live circuits under defined conditions, but repairs and replacements must preserve the certified design.
  • Documentation: Keep the certificates, markings and the loop assessment for each intrinsically safe circuit. Instructions must name the conditions of the certificate that affect installation and use.

Ex i vs. other types of protection

Other types, such as flameproof enclosure (Ex d), contain an explosion inside the enclosure. Ex i prevents ignition by limiting energy, which is why it dominates for instrumentation.

By knowledge.aitechdoc.world · Published September 26, 2026 · Last reviewed

Source: IEC 60079-11, Explosive atmospheres — Part 11: Equipment protection by intrinsic safety "i"

Definitions follow the cited standards and specifications. Where a source is a copyrighted publication, such as an ISO, IEC or EN standard, the definition is a close paraphrase, not a verbatim quotation, so as not to infringe copyright. We recommend reading the original publication. The sections “How it applies” are editorial commentary by AI TechDoc Knowledge and are not part of any standard.

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