TR СU 012/2011 On safety of the equipment for operation in explosive atmospheres

What is TR CU 012/2011?

The Technical Regulation TR CU 012/2011 provides strict safety requirements for electrical and non-electrical equipment operated in potentially explosive surroundings. Its primary goal is the protection of life, health, property, and the environment by ensuring that an explosion or a fire resulting from the use of the appliance is reliably prevented.

Explosion protection standards have evolved over decades. While the European Union relies on the ATEX Directive, the countries of the Eurasian Economic Union (EAEU) have established TR CU 012/2011 as their supreme legal framework for hazardous areas.

Equipment intended for use in potentially explosive environments must be designed and manufactured to withstand the effects of an explosion—including impact and heat—without sustaining damage, while continuing to operate normally or failing safely without igniting the surrounding atmosphere.

Area of application of TR CU 012/2011

The regulation strictly defines which products must undergo conformity assessment and which are exempt. The classification depends entirely on the presence of integrated explosion protection means.

Conformity Assessment under TR CU 012/2011

According to the regulation, the only permissible form of conformity assessment is EAC Ex Certification. A simple EAC Declaration is not legally valid for explosion-proof equipment under any circumstances.

The regulation requires mandatory involvement of an accredited certification body and an accredited testing laboratory within the EAEU. For serial production, a mandatory manufacturing audit is also required to verify that the quality management system ensures continuous compliance with Ex-standards.

Mandatory Technical Documentation

Article 6 of TR CU 012/2011 outlines specific requirements for the technical documentation that must be submitted in Russian (or the official language of the member state). Aside from standard documents like technical drawings and the Technical Passport, the regulation explicitly demands:

• Safety Justification: A comprehensive risk assessment evaluating hazards throughout the equipment's lifecycle.
• Ignition Hazard Assessment: Required particularly for non-electrical equipment, proving the absence of potential ignition sources (sparks, hot surfaces).
• Operating Manuals: Must include specific safety requirements, maintenance procedures, and conditions for safe operation in hazardous areas.

Marking Requirements according to TR CU 012/2011

The regulation sets extremely strict rules for marking. Products confirmed to conform with TR CU 012/2011 must be marked with both the official EAC conformity mark and the special Ex symbol.

Technical Requirements for the Ex Symbol:

• It consists of stylized letters “E” and “x”. The height of “x” must be 5/9 of the height of “E”.
• The minimum height of the symbol is 10 mm, with a height-to-width ratio of 11:8.
• The mark must be placed on a contrasting background and remain legible throughout the product's entire life cycle, even in harsh industrial environments.

Understanding the EAEU Ex Marking String

TR CU 012/2011 uses a detailed alphanumeric code to define exactly where and how the equipment can be used safely. This code must appear on the nameplate.

1. Equipment Level of Protection (EPL)

• 0 – Very high level: Ignition is unlikely even in case of rare malfunctions.
• 1 – High level: Safe in normal operation and expected malfunctions.
• 2 – Enhanced level: Safe in normal operation; provides protection during expected malfunctions.

For mining equipment (Group I), the Russian acronyms PO (Very High), PB (High), and RP (Enhanced) are used based on GOST 12.2.020-76.

2. Type of Ignition Protection

3. Equipment Group & Subdivision

• Group I: Mines and underground works susceptible to firedamp (Methane/Coal dust).
• Group II: Gas explosive atmospheres in surface industries.
  • Subdivisions: IIA (Propane), IIB (Ethylene), IIC (Hydrogen/Acetylene - highest danger).
• Group III: Dust hazardous areas.
  • Subdivisions: IIIA (Combustible flyings), IIIB (Non-conductive dust), IIIC (Conductive dust).

4. Temperature Class

Defines the maximum allowed surface temperature of the equipment to prevent it from igniting the surrounding gas/air mixture.

Example of a complete EAEU marking string: 1 Ex d IIC T4 Gb X

Overlapping Regulations

It should be noted that products subject to TR CU 012/2011 frequently fall under other general technical regulations of the EAEU simultaneously. Ex-equipment must often also comply with:

• TR CU 010/2011 On safety of machinery and equipment
• TR CU 004/2011 On safety of low-voltage equipment (if operated at 50-1000V AC)
• TR CU 020/2011 On electromagnetic compatibility
• TR CU 032/2013 On safety of pressure equipment (for pressurized systems in hazardous areas)

In such cases, a single EAC Ex Certificate may cover the Ex-aspects, while an additional EAC Declaration/Certificate might be issued to cover the EMC or Machinery requirements.