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EN ISO 11612: Comprehensive Guide for Heat Protective Clothing

EN ISO 11612 is the most widely recognized global standard for heat-protective textiles, used across Europe, Asia, and many other regions. It specifies performance requirements for protective clothing designed to protect workers from thermal hazards including flames, radiant heat, convective heat, contact heat, and molten metal splashes. Understanding this certification system helps safety managers and buyers select the right protective clothing for their specific workplace hazards.

Table of Contents

• What is EN ISO 11612?
• What Does EN ISO 11612 Protect Against?
• The EN ISO 11612 Letter Coding System: A–F
• How to Read an EN ISO 11612 Label
• Types of Products Covered by EN ISO 11612
• Areas of Applications for EN ISO 11612
• Geographic Adaptation of EN ISO 11612
• Standards Updates and Versions

What is EN ISO 11612?

EN ISO 11612 is a European standard that specifies minimum performance requirements for protective clothing used against heat and flame. Unlike application-specific standards, it focuses on fabric performance, how materials behave when exposed to different thermal hazards, making it applicable across multiple industries.

The standard is officially titled “Protective clothing, Protection against heat and flame, Minimum performance requirements" and is maintained by the International Organization for Standardization (ISO) and the European Committee for Standardization (CEN). It uses a letter coding system from A to F, which appears directly on garment labels to indicate the specific types of heat and flame protection provided, allowing safety managers and workers to quickly identify suitable protection.

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What Does EN ISO 11612 Protect Against?

EN ISO 11612 is used to protect where there is a need for garments with limited flame spread properties, and where the user is exposed to radiant, convective and/or contact heat and/or molten metal sprays or splashes.

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The EN ISO 11612 Letter Coding System: A–F

EN ISO 11612 uses a letter coding system from A to F to show different types of heat protection. Each letter represents a specific hazard and protective capability.

Code A: Limited Flame Spread

Code A tests for limited flame spread, meaning how well clothing resists catching fire and spreading flames across the material. This code has two levels:

Key Point: All certified EN ISO 11612 clothing must pass at least A1 or both A1 and A2. Code A is mandatory for all garments; you cannot have EN ISO 11612 certification without it.

Code B: Convective Heat Protection

Code B measures protection against convective heat from flames, the heat that travels through air currents and hot gases. Performance levels are measured using the Heat Transmission Index (HTI), which determines how long it takes for heat to reach a critical temperature (44°C/111°F) that would cause skin burns. Higher numbers indicate longer protection times:

The performance levels are:

Code	Time to Hole Formation
B1	4 to < 10 seconds
B2	10 to < 20 seconds
B3	20+ seconds

Key Point: Convective heat is a primary hazard in flash fire and welding environments.

Code C: Radiant Heat Protection

Code C shows protection against radiant heat like infrared rays, which travels directly from heat sources without requiring a medium. Performance levels are measured using the Radiant Heat Index (RHTI), similar to Code B methodology.

The four levels range from lowest to highest protection:

Code	Time to Hole Formation
C1	7 to < 20 seconds
C2	20 to < 50 seconds
C3	50 to < 95 seconds
C4	Minimum 95 seconds

Key Point: Radiant heat protection is critical in foundries, welding operations, and industrial settings with hot machinery.

Code D: Molten Metal Aluminum Splashes

Code D tests protection from molten aluminum splashes, measured by the weight of metal the garment can withstand in grams. A specific amount of liquid aluminium is poured onto the fabric with an underlying membrane simulating skin.

The membrane must remain intact after the test. The temperature of the molten aluminium is 780°C/1436°F (±20°C).

Code	Molten Metal Quantity
D1	100 g to < 200 g
D2	200 g to < 350 g
D3	Minimum 350 g

Key Point: Aluminium protection is commonly needed in the aerospace, automotive, and general manufacturing.

Code E: Molten Cast Iron

Code E measures protection from molten iron splashes. The test is carried out in a similar manner to Code D. Under the material being tested is a film of PVC to simulate human skin. The temperature of the molten iron is 1400°C/2552°F (±20°C).

The membrane must remain intact after the test. The temperature of the molten aluminium is 780°C/1436°F (±20°C).

Code	Molten Cast Iron Quantity
E1	60 to 120 g
E2	120 to 200 g
E3	Over 200 g

Key Point: Iron and steel foundries rely heavily on Code E protection.

Code F: Contact Heat

Code F tests contact heat protection when touching hot objects, direct contact with heated surfaces or equipment’s.

Code	Contact Heat Protection Time
F1	5 to 10 seconds
F2	10 to 15 seconds
F3	Over 15 seconds

Key Point: Contact heat occurs frequently in metalworking, welding, and manufacturing environments.

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How to Read an EN ISO 11612 Label

Every garment must be tested for Code A plus at least one other code. Higher numbers within each code indicate better protection levels. A typical EN ISO 11612 label might read:

EN ISO 11612: A1, B1, C3, E3, F0

• A1: Surface flame ignition
• B1: Convective heat protection for 4-10 seconds
• C3: Radiant heat protection for 50-95 seconds
• D3: Resistance to molten aluminium splash for a minimum of 350 grams
• E3: Resistance to molten cast iron for over 200 grams
• F0: No resistance to contact heat

The specific codes appear on the garment label to show what hazards it protects against. Understanding this shorthand helps to quickly match clothing to the workplace hazards.

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Types of Products Covered by EN ISO 11612

EN ISO 11612 applies to a wide range of protective clothing items. Understanding which products require this certification helps buyers identify appropriate PPE for their workplace.

Garments Certified to EN ISO 11612

• Shirts & jackets
• Pants & trousers
• Overalls & coveralls
• Aprons
• Waistcoats & vests
• Hood & head protection

Garments Not Certified to EN ISO 11612

Many manufacturers recommend wearing EN ISO 11612 certified garments as part of a complete protective ensemble that includes gloves (EN 407), footwear (EN ISO 20345), and headgear (EN 397). The overall protection level depends on the weakest link in the ensemble; all PPE must be appropriate for the hazard.

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Areas of Applications for EN ISO 11612

EN ISO 11612 protective clothing is essential across multiple industries where workers face thermal hazards:

• Welding & Metal Fabrication
• Foundries & Metal Casting
• Steel Mills & Iron Works
• Chemical Processing & Petrochemicals
• Glass & Ceramics Manufacturing
• Aerospace & Automotive Manufacturing

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Geographic Adaptation of EN ISO 11612

EN ISO 11612 is the mandatory standard across the European Union, governed by EU Directive 89/686/EEC on personal protective equipment. It is widely recognized and adopted in Asia, Australia, Canada, and many other regions as the primary heat protection standard.

European Union: Mandatory compliance for all heat-protective garments sold within EU member states. The Notified Body system ensures third-party certification and ongoing market surveillance.

United Kingdom: Following Brexit, the UK adopted EN ISO 11612 into British Standards (BS EN ISO 11612) and maintains equivalence with EU requirements through the UKCA (UK Conformity Assessed) marking system.

Asia-Pacific Region: Countries including Australia, New Zealand, and Singapore recognize EN ISO 11612 as the primary standard. Japan and South Korea have adopted similar standards with strong alignment to EN ISO 11612 requirements.

North America: In the United States and Canada, EN ISO 11612 coexists with NFPA standards (NFPA 2112 for flash fire protection). Many manufacturers design garments to meet both standards simultaneously to serve multinational companies and export markets. Canada’s CSA (Canadian Standards Association) recognizes EN ISO 11612 compliance.

Middle East and Africa: EN ISO 11612 is increasingly adopted, particularly in oil and gas operations where European regulatory influence is strong.

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Standards Updates and Versions

EN ISO 11612 is periodically revised to reflect new testing methods and fabric innovations. Always verify which edition a garment meets, as older versions may have different requirements or test parameters than current versions.

Official Sources for Current Information

For the most current information on EN ISO 11612 requirements, editions, and amendments, consult:

• The International Organization for Standardization (ISO): www.iso.org
• The European Committee for Standardization (CEN): www.cen.eu
• Notified Bodies and Competent Authorities in your jurisdiction

Employers and safety professionals should regularly review official standard documentation and regulatory guidance to ensure ongoing compliance and worker safety.