EN ISO 11612:2015

Clothing to Protect Against Heat & Flame

EN ISO 11612:2015 outlines the test methods that lay the minimum performance requirements for protective workwear constructed from flexible materials, intended to protect the wearer's body (excluding hands) from heat and flame. The standard applies to protective clothing claiming to protect while conducting industry applications, which pose risk of radiant heat, convective or contact heat or exposure to splatters of molten metal (aluminium or iron).
This standard replaces EN 531 which has been formally withdrawn by European Standards. However, the pictogram has remained the same.

EN ISO 11612:2015 lists and categorizes safety hazards that are the result of heat and flame risks. With each of these hazard categories, three performance levels denote if exposure to low, medium or high risks can be withstood. For radiant heat, there is a fourth level which considers protection against extreme exposure to heat from high-performance materials such as aluminised materials.

Letter A

Limited Flame Spread

The two tests conducted for letter A - A1 and A2 - are performed following EN ISO 15025:2016 Protective Clothing - Protection against flame - Method of test for limited flame spread. These test methods dictate procedures for determining flame spread as a result of surface or bottom-edge ignition. It measures the effects of the sample fabric on heat exposure against specified set tolerances.

A1-Surface Ignition

Surface ignition is tested by applying the flame horizontally and measuring flame spread. For fabrics to meet A1 requirements, they must demonstrate a mean afterflame and afterglow time of less than two seconds. The fabric sample must not generate flaming or molten debris. Additionally, there should be no hole formation of greater than 5mm evident on the sample, excluding inner-lining specifically for other forms of protection.

Performance RatingSeconds

A2-Edge Ignition

Edge ignition tests are conducted by applying the flame laterally to the fabric sample. Likewise, the sample must not create flaming or molten debris and must demonstrate a mean afterflame and afterglow time of less than two seconds. The flame must not reach upper or vertical edges.

Performance RatingSeconds

Letter B

Convective Heat

A garments outer surface that does not ignite can still cause the wearer damage through the heat that forms when the wearer comes in contact with the flame. A convective heat test, conducted in accordance with EN ISO 9151:2016, measures the heat that passes through the garment when in contact with flame. The fabric is exposed to a flame. The time it takes for the topside of the sample to reach 24°C is measured with a calorimeter and used to assign a number value.

Performance RatingSeconds
B14 - 10s
B210 - 20s
B321s and longer

Letter C

Radiant Heat

Radiant heat can put a wearer at risk of injury even at a low temperature if exposed over long periods. Testing garments to EN ISO 6942:2002 involves two complementary methods of determining how the material of a garment will behave when subjected to heat radiation. During the test, a fabric sample is exposed to radiant heat or infrared rays, while the temperature of the materials unexposed side is measured using a calorimeter. Similar to the convective heat test, the duration for the fabric taken to reach 24°C is recorded, and the results translated into a 1-4 performance rating.

Performance RatingSeconds
C17 - 20s
C220 - 50s
C350 - 95s
C495s and longer

Letter D

Molten Aluminium Splash

The heat penetration resistance of a fabric intended to protect the wearer from large splashes of molten metals is measured and judged using the test method EN ISO 9185:2007. Within this standard, performance levels are set in terms of the mass of iron and aluminium that can be splashed onto a test sample without producing damage to the heat sensor film. To achieve a D level performance rating, the garment must prevent the wearer from coming into contact with molten aluminium splashes of a minimum weight of 100 grams.

Performance RatingGrams
D1100 - 200g
D2200 - 350g
D3300g or more

Letter E

Molten Iron Splash

Molten Iron is also classified amongst the wide range of hot molten metals that can potentially penetrate clothing, as tested using the EN ISO 9185:2007 test method. The amount of molten iron the garment fabric can protect against is given a performance level from 1-3.

Performance RatingGrams
E160 - 120g
E2120 - 200g
E3200g or more

Letter F

Contact Heat

The fabrics protection against direct contact with hot substances or hot surfaces is determined using ISO 12127:1996. The test observes the heat transferred between a heated cylinder and the fabric sample when brought close together. An extensive range of potential conditions and hazards can arise with exposure to high contact heat. However, the test method indicates how well the fabric sample will protect the wearer from contact temperatures within 100°C and 500°C.

Performance RatingSeconds
F15 - 10s
F210 - 15s
F315s or longer

ISO 11612:2015 excludes head, hands and feet protection, only referencing gaiters, hoods and overboots. There is no reference to gloves or requirements for visors and respiratory equipment for wear alongside hooded garments for adequate fire protection. Additionally, an optional manikin flame engulfment test outlined in ISO 13506-1 or ISO 13506-2 could be conducted, with a minimum expected result of 4 seconds exposure.