ISO 11612 Clothing Providing Protection Against Heat and Flame - Minimum Performance Requirements

The standard “ISO 11612 Protective clothing - Clothing providing protection against heat and flame - Minimum performance requirements” published by the International Organization for Standardization (ISO) describes the performance requirements for protective clothing made of flexible materials designed to protect the body of the wearer, excluding the hands, from heat and flame.

To protect the wearer's head and feet, the only items of protective clothing covered by this standard are gaiters, hoods, and overboots. However, visors and respirator requirements are not specified for hoods.

These Internationally declared performance requirements apply to protective clothing that can be worn for a wide variety of end uses where clothing with limited flame spread characteristics is needed and where the wearer may be exposed to radiant, convective or contact heat or molten metal splashes.

The purpose of this standard is to provide minimum performance requirements for heat and flame protective clothing that can be worn for a wide range of end uses. Other standards related to heat and flame protective clothing have also been published, but these are primarily applicable to specific products or end uses.

There are three performance levels for most of the hazards specified in the ISO 11612 standard:

• Level 1 to indicate low risk exposure
• Level 2 to indicate medium risk exposure
• Level 3 to indicate high risk exposure

For protection against excessive exposure to radiant heat, a fourth performance level must be considered: high-performance materials such as aluminized and similar materials. The level of personal protection to be provided depends on the results of the risk assessment, and some comments on the risk assessment are included in the annex to this standard (Annex D).

For complete protection against exposure to heat and flame, the head, face, hands and feet may need to be protected with appropriate personal protective equipment and, in some cases, appropriate respiratory protection may also be required.

In short, the ISO 11612 standard specifies the performance requirements for protective clothing made of flexible materials designed to protect the wearer's body, excluding the hands, from heat and flame. This standard is widely applied in industries such as welding, foundry, metalworking, petrochemical, and other environments where workers are exposed to risks from radiant, convective, or contact heat, as well as molten metal splashes.

ISO 11612 also covers special protective equipment for the head and feet, such as gaiters, hoods, and overboots, but does not cover requirements for visors or respirators. This standard is applicable to a wide range of end uses where limited flame spread characteristics are required and workers may encounter radiant heat, convective heat, contact heat, or molten metal splash.

The general design and performance requirements presented by this standard are briefly as follows:

• Design requirements: Garments must provide proper fit and drape, with at least 20cm of overlap between jacket and trousers when standing. Fasteners require protective flaps, and there are restrictions on features such as collars or side vents to minimise heat penetration.
• Material performance: Materials must be heat resistant at 180 degrees (can be tested at 260 degrees optionally) and must demonstrate limited flame spread, tensile strength, tear strength and seam strength.
• Labelling and marking: Garments must be clearly labelled with the CE marking indicating compliance and include information on protective features.

The ISO 11612 standard provides various test methods for assessing the protective performance of clothing. To comply with this standard, clothing must meet minimum performance levels for the limited flame spread test and at least one of the other indices.

The test methods described in this standard are:

• A. Limited flame spread: This test method evaluates the resistance of a fabric to flame spread. A flame is applied to the material, either on the surface (A1) or on the edge (A2), for 10 seconds. The material passes the test if it does not continue to burn, there is no hole formation, and no burning or molten material drips. The flame and glow durations should not exceed an average of 2 seconds.
  • A1 surface ignition
  • A2 edge ignition
• B. Convective heat resistance: This test method measures the time it takes for a 24-degree temperature increase to occur on the opposite side of the fabric when exposed to flame, using a calorimeter. The classification is as follows:
  • B1: 4 to maximum 10 seconds
  • B2: 10 to maximum 20 seconds
  • B3: At least 20 seconds
• C. Radiant heat resistance: When using this test method, the fabric is exposed to radiant heat (20 kW/m2) and the time it takes to reach a temperature increase of 24 degrees is measured using a calorimeter. The classification is as follows:
  • C1: 7 to maximum 10 seconds
  • C2: 20 to maximum 50 seconds
  • C3: 50 to maximum 95 seconds
  • C4: At least 95 seconds
• C. Molten aluminum splash: This test method involves pouring a specific amount of molten aluminum onto a fabric with a membrane that mimics human skin placed underneath. The membrane must not show any damage or deformation. The classification is as follows:
  • D1: 100g to maximum 200g
  • D2: 200g to maximum 350g
  • D3: At least 350 g
• E. Molten iron splash: When using this test method, similar to the molten aluminum test, a certain amount of molten iron is poured onto a fabric and a PVC film that mimics leather is placed underneath. The film must remain undamaged. The classification is as follows:
  • E1: 60g to maximum 120g
  • E2: 120g to maximum 200g
  • E3: At least 200 g
• F. Contact heat resistance: When using this test method, the fabric is exposed to a heat source at 250 degrees Celsius and the time it takes to reach the temperature increase on the opposite side is measured. The classification is as follows:
  • F1: 5 to maximum 10 seconds
  • F2: 10 to maximum 15 seconds
  • F3: At least 15 seconds

The ISO 11612 standard is critical in industries where workers are exposed to thermal hazards, including:

• Welding: Provides protection against sparks and heat resulting from welding operations.
• Foundry industry: Protects workers in iron, steel or aluminum production from molten metal splashes.
• Oil and gas: Provides protection against flash fires and heat exposure.
• Heavy industry and maintenance: Provides safety in environments with high heat or flame risks.
• Refineries: Provides protection against potential fire hazards.

Compliance with the ISO 11612 standard ensures that protective clothing provides a reliable barrier against heat and flame hazards, reducing the risk of serious injury or death. Flame-retardant materials self-extinguish once the ignition source is removed, making them essential for high-risk environments. Employers should select certified clothing and ensure proper use and maintenance to maximize safety.

Ultimately, the ISO 11612 standard is a vital framework for ensuring the safety of workers in environments exposed to heat and flame. By establishing rigorous testing and performance requirements, it ensures that protective clothing can withstand a variety of thermal hazards while maintaining functionality and comfort. Understanding this standard, its test methods, and its applications helps employers and workers select appropriate personal protective equipment and create safer workplaces in high-risk industries.

Our organization, which has been operating for many years and meticulously follows global developments in science and technology, employs a team of experienced professionals and a broad infrastructure to conduct testing, measurement, and analysis in a wide range of areas for businesses across all sectors. In this context, we also provide testing services in accordance with the ISO 11612 Protective clothing - Clothing providing protection against heat and flame - Minimum performance requirements standard.