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EN ISO 11612: Heat & Flame Protective Clothing Standards and Performance Codes Explained
In the field of industrial safety, EN ISO 11612 is the gold standard for evaluating the performance of heat and flame-resistant protective clothing. For procurement professionals in Oil & Gas, Metallurgy, Utilities, and Manufacturing, understanding the A-F performance codes of this standard is critical to ensuring compliance and safeguarding worker lives.
This guide provides a comprehensive breakdown of the EN ISO 11612 test methods, the meaning of the six performance modules (A-F), and the core differences between this standard, the welding standard EN ISO 11611, and the American standard NFPA 2112.
What Is EN ISO 11612?
EN ISO 11612:2015 (Protective clothing — Clothing to protect against heat and flame) is an international standard specifying performance requirements for protective clothing made from flexible materials. Its core purpose is to protect workers from second-degree burns during short-term exposure to flame, radiant heat, or molten metal splashes.
Key Facts:
- Mandatory Baseline: All fabrics compliant with this standard must first pass the Code A (Limited Flame Spread) test.
- Exclusions: This standard does not apply to structural firefighting gear (refer to EN 469) or dedicated welding protection (usually requires EN ISO 11611).
Which Industries Require EN ISO 11612?
EN ISO 11612 is a versatile industrial heat protection standard. Its “modular” nature makes it applicable to various industries with thermal hazards. If your work environment involves the following risks, this certification is typically mandatory:
- Oil & Gas: For flash fire risks on drilling platforms and refineries (often combined with anti-static EN 1149-5).
- Utilities & Power: To prevent clothing ignition from electric arcs (often combined with IEC 61482-2).
- Metallurgy & Foundries: High-risk environments involving molten metal splashes (Focus on Codes D and E).
- Automotive & General Manufacturing: Assembly lines involving sparks and heat transmission.
- Cement & Glass Manufacturing: Roles involving high-temperature kiln operations (Focus on Code C Radiant Heat).
EN ISO 11612 Core Test Methods & Technical Parameters
To achieve EN ISO 11612 certification, protective clothing or fabrics must undergo a rigorous series of physical tests. Each performance code (A-F) corresponds to a specific ISO test standard. Below is the technical mapping table:
| Performance Code | Test Name | ISO Standard | Test Purpose |
|---|---|---|---|
| Code A | Limited Flame Spread | ISO 15025 | Evaluates self-extinguishing properties after contact with a naked flame. |
| Code B | Convective Heat | ISO 9151 | Tests thermal insulation when surrounded by flame. |
| Code C | Radiant Heat | ISO 6942 | Tests time to burn when facing a strong radiant heat source. |
| Code D | Molten Aluminum Splash | ISO 9185 | Tests resistance to adhesion and burn-through by molten aluminum. |
| Code E | Molten Iron Splash | ISO 9185 | Tests resistance to adhesion and burn-through by molten iron. |
| Code F | Contact Heat | ISO 12127 | Tests protection time when contacting objects at 250°C. |
Detailed Explanation of Performance Codes (A-F)
The numbers following the codes on a certificate (1-3 or 1-4) indicate the level of protection. Higher numbers represent stronger protection. Here are the specific definitions:
A: Limited Flame Spread (Based on ISO 15025)
This is the entry threshold. During the test, the fabric must not drip, shrink, or develop a hole.
- A1 (Surface Ignition): Flame applied directly to the fabric surface for 10 seconds.
- A2 (Edge Ignition): Flame applied to the bottom edge of the folded fabric for 10 seconds.
Procurement Tip: Most high-spec tenders require fabrics to pass both A1 + A2.
B: Convective Heat (Based on ISO 9151)
This measures the time required for heat to penetrate the fabric and raise the temperature of a calorimeter (simulating skin) by 24°C (HTI 24).
| Level | HTI 24 (Seconds) | Protection Level |
|---|---|---|
| B1 | 4.0 – < 10.0 | Basic Protection |
| B2 | 10.0 – < 20.0 | Medium Protection |
| B3 | ≥ 20.0 | High Protection |
C: Radiant Heat (Based on ISO 6942)
Simulates heat radiation from high-temperature sources. The test measures the time to reach a second-degree burn threshold (RHTI 24) under specific heat flux density.
| Level | RHTI 24 (Seconds) | Typical Application |
|---|---|---|
| C1 | 7.0 – < 20.0 | General Industrial |
| C2 | 20.0 – < 50.0 | Proximity to Heat Sources |
| C3 | 50.0 – < 95.0 | High Radiant Environments |
| C4 | ≥ 95.0 | Extreme Environments (Aluminized fabric usually required) |
D & E: Molten Metal Splash (Based on ISO 9185)
Evaluates if molten metal adheres to the fabric or damages the skin simulation behind it.
- D (Levels 1-3): Uses Molten Aluminum and Cryolite.
- E (Levels 1-3): Uses Molten Iron.
Grading is based on the minimum weight (grams) of molten metal required to damage the artificial skin. Higher levels withstand larger splashes.
F: Contact Heat (Based on ISO 12127)
Simulates accidental contact with hot objects at 250°C.
- F1: 5.0 – < 10.0 Seconds
- F2: 10.0 – < 15.0 Seconds
- F3: ≥ 15.0 Seconds
EN ISO 11612 vs. NFPA 2112: Core Differences
This is the most common question in global procurement. While both are FR standards, their focus and testing logic differ significantly:
| Comparison Dimension | EN ISO 11612 (EU/International) | NFPA 2112 (USA/North America) |
|---|---|---|
| Core Logic | Modular Grading (A-F), rates specific thermal hazards individually. | Pass/Fail System, focuses on overall Flash Fire protection. |
| Mannequin Test | Optional (ISO 13506). Not mandatory for certification. | Mandatory (ASTM F1930). Requires <50% body burn after a 3-second flash fire. |
| Washing Test | Typically tested after 5 or 50 wash cycles. | Mandatory testing after 100 Industrial Wash cycles. |
| Target Market | Europe, Asia, Middle East, General Industry. | USA, North America, Offshore Oil Rigs. |
EN ISO 11612 vs. EN ISO 11611: Welding Differences
Many clients confuse these two standards. Simply put, EN ISO 11612 is the “General Heat & Flame” standard, while EN ISO 11611 is the “Welding & Allied Processes” standard. EN ISO 11611 is ‘specialized professional gear’ for welders, while EN ISO 11612 is ‘general-purpose fire-resistant clothing’ for industrial heat hazards. Here is the detailed comparison:
| Comparison Dimension | EN ISO 11612 (General Heat) | EN ISO 11611 (Welding Specific) |
|---|---|---|
| Primary Use | Protection against radiant, convective, contact heat, and large molten splashes. | Protection against welding Spatter, radiant heat, and accidental electrical shock. |
| Electrical Insulation | No Requirement. | Mandatory. Resistance must be > 10^5 Ω at 100V DC to prevent electric shock. |
| Metal Splash Test | Large Splash (D/E): Tests massive amounts (grams) of molten metal poured onto fabric. | Small Spatter (Impact): Tests the number of small drops required to raise temperature. |
| Grading System | A-F Performance Codes. | Class 1 (Light Welding) and Class 2 (Heavy/Confined Welding). |
Conclusion: If workers are engaged in professional welding, EN ISO 11612 alone is insufficient. They must also be certified to EN ISO 11611 to ensure electrical insulation and protection against small spatters.
Often Overlooked Design Requirements
Passing the fabric test alone does not make a garment EN ISO 11612 compliant. The finished garment must adhere to strict design specifications to prevent heat entrapment or molten metal retention:
- Pocket Flaps: All external pockets must have flaps, and the flap width must exceed the pocket opening by at least 20mm to prevent sparks from entering.
- Covered Metal: Zippers, buttons, and other metal accessories must not be exposed on the garment surface; they must be covered by fabric to prevent heat transfer burns.
- Cuffs & Hems: No turn-ups (cuffs) are allowed on trouser legs to prevent the accumulation of molten metal or flammable chemicals.
How to Select Certified Fabrics?
Choosing the right fabric material depends entirely on your specific working conditions:
- FR Cotton: Treated via Proban or Pyrovatex technologies. Cost-effective and breathable. Suitable for general industry (A1, B1, C1).
- Modacrylic/Cotton Blends: Inherently flame resistant, soft hand-feel, and typically offers good electric arc protection properties.
- Aramid (Nomex/Kevlar): Inherently flame resistant, high heat resistance, and high strength. Suitable for extreme environments like petrochemicals (Achieves higher ratings).
- Aluminized Fabrics: Designed specifically for C3/C4 high radiant heat environments (e.g., working near foundry furnaces).
Frequently Asked Questions (FAQ)
Q: Does EN ISO 11612 compliance guarantee Arc Flash protection?
A: No. While EN ISO 11612 covers heat and flame resistance, Arc Flash is a distinct hazard. If you require arc flash protection, you must verify that the product also meets the IEC 61482-2 standard and check its ATPV or EBT rating.
Q: Why do some certificates only show A1 and not A2?
A: This depends on the test selection. A1 tests surface ignition, while A2 tests edge ignition. Some fabrics or specific end-uses may only require A1. However, for global versatility, we recommend procuring fabrics that pass both A1 + A2.
Q: What is the difference between EN ISO 11612 and EN ISO 14116?
A: EN ISO 14116 (formerly EN 533) is a lower-level standard solely for “Limited Flame Spread.” It does not include tests for Convective Heat (B), Radiant Heat (C), etc. If the risk is minimal (occasional exposure only), 14116 may suffice; but for regular industrial hazards, 11612 is mandatory.
