Overview of ATEX Equipment Markings and Protection Levels

This document provides detailed explanations of ATEX (ATmosphères EXplosibles) equipment markings, focusing on equipment groups, categories, types of protection, temperature classifications, gas groups, and equipment protection levels relevant to explosive atmospheres.

1. Equipment Group and Category

• Equipment Group II: Intended for surface industries (non-mining).
• Equipment Category (1G, 3G): Indicates the level of protection and intended use in explosive gas atmospheres. Category 1G is for very high protection (safe in normal operation and rare faults), while 3G is for equipment with lower protection levels.

2. Type of Protection

• Ex ia (Intrinsically Safe): Equipment designed to be safe even in the presence of explosive atmospheres by limiting energy to prevent ignition.
• Ex nA (Non-sparking): Equipment designed to prevent sparks during normal operation but not necessarily intrinsically safe.

3. Gas Group and Subgroup

• Gas Group II C: Covers the most easily ignitable gases (e.g., hydrogen, acetylene).
• Gas Subgroup [ia Ga]: Indicates intrinsic safety level and suitability for use in explosive atmospheres continuously present.

4. Temperature Classification

• Defines the maximum surface temperature the equipment can reach to avoid ignition of surrounding gases.
• Classifications include T4 (max 135°C) and T6 (max 85°C), with T6 being the most restrictive.

5. Equipment Protection Level (EPL)

• Ga: Equipment safe in explosive atmospheres continuously present or likely to occur.
• Gc: Equipment safe in explosive atmospheres during normal operation only.

6. Application Context

• Equipment marked with II 1G Ex ia IIC T6 Ga is suitable for mining and surface industries with the highest safety requirements, intrinsically safe, and suitable for the most easily ignitable gases.
• Equipment marked with II (1) 3G Ex nA [ia Ga] IIC T4 Gc is non-sparking, suitable for surface industries, and safe under normal operation conditions.

Summary Table of Key Parameters

Critical Points and Best Practices

• Selection of equipment must consider the gas group and temperature classification to prevent ignition risks.
• Intrinsic safety (Ex ia) provides the highest level of protection and is preferred in environments with continuous explosive atmospheres.
• Non-sparking equipment (Ex nA) is suitable where explosive atmospheres are less likely or only present during normal operation.
• Understanding the Equipment Protection Level (EPL) is essential for compliance and safety assurance.

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