Table of Contents

Introduction

A gas detector installed in an oil & gas or petrochemical plant is itself electrical equipment in a potentially explosive atmosphere. If it is not correctly certified, it can become the ignition source. For buyers in Russia, Central Asia and the Middle East, understanding the certification landscape — EAC, ATEX and IECEx — is therefore not paperwork: it determines whether the instrument can be legally accepted on site and whether the safety case holds up in an incident.

This article explains what each certification means, how to read an Ex marking, and which scheme applies where. North American UL/NEC approvals are mentioned only briefly, as a secondary, regional note.

Why Explosion Protection Exists

Flammable gas or vapour mixed with air inside the explosive concentration range can ignite from a spark or hot surface. Protection standards divide hazards into zones based on how likely an explosive atmosphere is to be present: Zone 0 (continuously or for long periods), Zone 1 (likely in normal operation) and Zone 2 (not likely, and if present only briefly). Electrical equipment is then designed to one of several protection concepts, two of which dominate gas detectors:

Intrinsic safety “i”: limits the energy and temperature so the equipment cannot spark hot enough to ignite the gas — used in portable instruments and low-power devices, e.g. Ex ia.
Flameproof enclosure — “d”: contains any internal explosion and cools escaping gases so they cannot ignite the surrounding atmosphere — used in heavier fixed transmitters, e.g. Ex d.

EAC / TR CU 012/2011 (EAEU — Russia & Customs Union)

For the Eurasian Economic Union — Russia, Kazakhstan, Belarus, Armenia and Kyrgyzstan — equipment for explosive atmospheres must meet Technical Regulation TR CU (EAEU) 012/2011 “On safety of equipment for work in explosive atmospheres”. Compliance is demonstrated by certification, and the product must carry the EAC mark. Suppliers shipping gas detectors into Russia and the EAEU should confirm the TR CU 012/2011 certificate and Declaration before customs clearance; a private ATEX or IECEx certificate alone is generally not sufficient as the legal basis for EAEU market access.

ATEX (European Union)

ATEX refers to the EU directive 2014/34/EU (equipment and protective systems intended for use in potentially explosive atmospheres), supported by the EN 60079 series harmonised standards. A CE/ATEX-marked device can be placed on the EU market and, because EN 60079 is widely recognised, is frequently accepted by Middle East oil & gas operators and their contractors. ATEX defines both equipment protection levels (EPL Ga/Gb/Gc) and equipment groups and temperature classes.

IECEx (International)

The IECEx system applies the international IEC 60079 series and offers international certification to a common set of test methods. IECEx certificates are often the technical basis accepted across countries that do not run their own explosive-atmosphere regime, and they underpin many ATEX and national conversions. For exporters, holding IECEx plus the local EAC/TR CU document is the strongest, most transferable combination.

How to Read an Ex Marking

An Ex marking packs a lot of information. Two Hangwei examples make it concrete:

Ex ia IIC T4 Ga (HD620 portable): intrinsic safety, suitable for gas group IIC (including hydrogen/acetylene), temperature class T4 (surface/ignition temperature ≤ 135 °C), equipment protection level Ga (Zone 0).
Ex d IIC T6 Gb (HD9300 fixed): flameproof enclosure, IIC, T6 (≤ 85 °C), EPL Gb (Zone 1).

The temperature class (T-number) must be at least as cold as the gas’s auto-ignition temperature in the plant; the gas group must cover the hardest gas present. Match the marking to the site risk assessment — never assume a lower class is acceptable.

Comparing the Schemes

Scheme	Scope	Basis	Mark / acceptance
EAC / TR CU 012/2011	EAEU (Russia, KZ, BY, AM, KG)	EAEU technical regulation	EAC mark — mandatory for EAEU
ATEX	European Union	Directive 2014/34/EU + EN 60079	CE/ATEX — widely accepted in ME
IECEx	International	IEC 60079 series	IECEx certificate — global technical basis
UL / NEC (secondary)	North America	UL 60079 / NFPA 70 NEC	US/Canada — not required for EAEU/ME

For a Middle East hydrocarbon terminal, ATEX or IECEx is typically acceptable to the operator; for a project in Russia, the EAC/TR CU 012/2011 document is the legally required one. Confirm the exact requirement with the end customer before quotation.

Middle East Context

Gulf-region oil & gas, refining and seawater desalination plants run under high ambient temperatures and corrosive, salty air. Certification interacts with environmental ratings: even a correctly Ex-marked detector needs an adequate enclosure temperature range and ingress protection to survive -40°C cold snaps to 70°C summer surfaces and salt-laden humidity. The HD9300 fixed transmitter is specified over -40 to +70 °C with dual relays and IR remote calibration, suiting these demanding outdoor installations.

FAQ

What is the difference between ATEX and IECEx?

ATEX is the EU regulatory framework (directive + EN 60079 harmonised standards) for placing equipment on the EU market. IECEx is the international IEC 60079 certification system. They share test methods; ATEX has a regulatory/CE dimension while IECEx is an internationally recognised certificate.

Do I need EAC certification to sell gas detectors in Russia?

Yes. Equipment intended for explosive atmospheres must comply with TR CU 012/2011 and carry the EAC mark for the EAEU market. ATEX or IECEx alone does not replace it.

What does “Ex d IIC T6 Gb” mean?

Flameproof enclosure (d), suitable for gas group IIC, temperature class T6 (≤ 85 °C), equipment protection level Gb for Zone 1. It describes how safely the device behaves in an explosive atmosphere.

Is UL/NEC required in the Middle East or Russia?

Generally no. UL/NEC is the North American approach. EAEU projects require EAC/TR CU 012/2011; Middle East hydrocarbon operators usually accept ATEX or IECEx. UL/NEC is relevant only for North American-specified projects.

Can one detector carry multiple certificates?

Yes. Many manufacturers certify the same design to IECEx and ATEX, and separately to TR CU 012/2011 where required. Ask the supplier which certificates accompany the specific model you are buying.

Get Expert Guidance

Hangwei Sensors supplies explosion-protected fixed and portable gas detectors built to EN/IEC 60079 principles, with Ex markings such as Ex d IIC T6 Gb (HD9300 fixed) and Ex ia IIC T4 Ga (HD620 portable). We work with distributors and EPC contractors to assemble the correct certification package — EAC/TR CU 012/2011 for Russia and the EAEU, and ATEX/IECEx for Middle East hydrocarbon projects — backed by 20+ years of manufacturing, 20 patents and 10 production lines.

Fixed explosion-proof detector: HD9300 Fixed Gas Detector (Ex d IIC T6 Gb)

Intrinsically safe portable: HD620 Four-In-One Pump Detector (Ex ia IIC T4 Ga)

About the manufacturer: Hangwei Sensors — About Us

Contact Hangwei Sensors

Email: hw@hangweisensors.com · Phone: +86 371 6667 0886 · Website: https://www.hangweisensors.com/