Flame resistant clothing standards: EN ISO 11612 codes, EN ISO 11611 classes and arc protection

How to read ‘A1 A2 B1 C1 E2 F1’ on a label

The label line is shorthand for a test report. In the laboratory report mentioned in the first section, the fabric was an FR twill that the applicant declared as 245 g/m², 80% cotton, 19% polyester and 1% antistatic fibre. After five washes it scored 5.7 s in convective heat (B1), 11.8 s in radiant heat (C1), 8.6 s in contact heat (F1) and 283 g with molten aluminium (D2). None of four molten iron pours of about 200 g damaged the film behind it (E3). Its label line is A1 A2 B1 C1 D2 E3 F1.

Worked examples from the UK Health and Safety Executive (HSE) show the same logic on the shop floor. Casting iron into floor moulds from a ladle on an overhead crane: trousers marked E1. Hand-charging an induction furnace with aluminium scrap, bales and ingots, where trapped air or moisture can throw out molten metal: jacket and trousers marked D3.

Codes describe the fabric, not the cut. HSE's guidance covers the cut too: when the wearer bends down the jacket should still cover the trouser waist, trouser legs should have no turn-ups and be cut to sit over the top of the boot, and outer garments should have fastenings that release quickly in an emergency. Those points belong in the same quote discussion as the code.

The line in this section's heading, EN ISO 11612 A1 A2 B1 C1 E2 F1 on a coverall, reads element by element like this:

• A1 and A2: the fabric put itself out whether the flame hit its face or its edge. A2 matters wherever hems, cuffs and sleeve ends can catch.
• B1: in direct flame, the sensor behind the fabric took between 4 and 10 seconds to rise by 24 °C. That is a short margin for getting clear of a flash, not a working time inside flame.
• C1: under 20 kW/m² of radiant heat the same rise took 7 to 20 seconds. Jobs that keep people in front of a furnace for long stretches need a higher C level.
• E2: the molten iron splash index, worked out from the pour mass at which the PVC skin-simulant film behind the fabric starts to be damaged, fell between 120 and 200 g, with the iron poured at around 1,400 °C. A higher index means the fabric can carry more metal before the film is harmed. HSE treats the E codes as generally acceptable for molten steel, copper and brass as well.
• F1: pressed onto a 250 °C surface, the fabric reached its threshold time after 5 to 10 seconds. Think of leaning on a hot pipe or catching a hot casting with an elbow.
• No D: no claim for molten aluminium. A good iron result tells you nothing about aluminium, so this coverall does not belong in an aluminium foundry.

EN ISO 11611 Class 1 vs Class 2 for welding clothing

EN ISO 11611 covers the coveralls, jackets, trousers, aprons, sleeves, gaiters and hoods worn for welding and allied processes. It deals with small splashes of molten metal (spatter), short contact with flame and radiant heat from the welding arc. The clothing must also have enough electrical resistance to reduce the risk of shock from brief, accidental contact with live conductors at up to roughly 100 V DC.

The two classes follow the severity of the job. Class 1 is for techniques and situations that throw less spatter and radiant heat; Class 2 is for heavier spatter and more heat. Two tests draw the line, and Annex A of the standard lists typical work for each class.

One Annex A detail is easy to miss: plasma cutting by machine sits under Class 1, while the same cut made by hand moves to Class 2. Another: a high E level under EN ISO 11612 does not make a fabric Class 2 for welding. The E3 fabric from the report above stopped at 17 drops in the spatter test and gave 11.8 s in radiant heat, which made it Class 1 under EN ISO 11611.

There is an edition gap as well. ISO published a third edition, ISO 11611:2024, on 18 June 2024; it deals with protection against UV radiation in three risk levels. CEN, the European standards body, deleted its project to adopt that text as EN ISO 11611 in August 2024. A revision is still under way, but the European text in force remains EN ISO 11611:2015, which is why that date keeps appearing on labels and certificates.

Arc flash clothing: IEC 61482-2, APC classes, ATPV and ELIM

An electric arc is a different load from a flame. It releases a large amount of heat in a fraction of a second, and none of the EN ISO 11612 tests measure it. Arc flash clothing is therefore assessed to IEC 61482-2. The international edition dates from 2018 and replaced the 2009 text; the European version is EN 61482-2:2020. The standard deals only with the thermal effects of the arc. Electric shock, noise, light and pressure are outside its scope, and so is eye, face, hand and foot protection, which comes from separate products.

There are two routes to a rating. In the box test (IEC 61482-1-2) the arc is directed at the sample inside a box and lasts 500 milliseconds. A fabric or garment that passes the 4 kA test is classed APC 1; one that passes at 7 kA is APC 2. Passing means no melting through to the inner side, afterflame of no more than 5 seconds, no hole larger than 5 mm, and every sensor reading below the Stoll curve, the heat-versus-time line that marks the onset of a second-degree burn.

The open arc test (IEC 61482-1-1) exposes samples to rising incident energies and reports a number. ATPV is the energy at which there is a 50% probability that heat through the fabric reaches the second-degree burn threshold. ELIM is the energy below which every result stayed under the Stoll curve with no breakopen; it entered the requirements as a rating value in 2018 and is the more conservative figure. EBT is the energy at which there is a 50% probability of the fabric breaking open.

Ratings are given in kJ/m² or cal/cm². One cal/cm² equals 41.868 kJ/m², so 8 cal/cm² is about 335 kJ/m². Selection starts from the incident energy that the arc risk assessment calculates at the working distance, and the clothing's arc rating should not fall below it. For layered clothing the rating comes from testing the layers together. It cannot be worked out by adding up individual ratings.

EN ISO 14116: when limited flame spread is enough

EN ISO 14116 makes no claim about heat. Its job is narrower: to stop clothing from catching and becoming a hazard itself during occasional, brief contact with a small flame. Where heat protection is needed too, the standard points to EN ISO 11612. Materials are tested with the surface-ignition procedure of ISO 15025 and graded into one of three indices, Index 3 being the strictest.

Index 1 carries a condition of use that is easy to overlook. Index 1 material must not touch the skin, and an Index 1 garment has to be worn over an Index 2, Index 3 or EN ISO 11612 garment. An Index 1 hi-vis vest worn over an FR coverall keeps that order. The same vest over an ordinary T-shirt breaks it. The criteria for each index:

• Index 1: the flame does not reach the top or side edge, no flaming debris falls, and afterglow does not spread from the charred area into sound fabric. Holes may form.
• Index 2: everything in Index 1, plus no hole formation.
• Index 3: everything in Index 2, plus afterflame of no more than 2 seconds.

Flame resistant vs flame retardant: inherent and treated fabrics

The two terms get swapped all the time, though careful usage keeps them apart. Flame resistant is a behaviour: the fabric resists ignition and stops burning soon after the flame source is removed. Flame retardant usually refers to the chemistry, often a finish, that gives an otherwise flammable fibre that behaviour. Neither term means the fabric cannot burn.

Inherent FR fabrics owe their flame resistance to the fibre's own chemical structure; aramid and modacrylic blends belong here. Washing cannot strip the property away, and what ends the garment's life is abrasion, thinning and tears. Treated FR fabrics start as cotton or a cotton-rich blend and receive a durable flame retardant finish. An FR fabric listed as 100% cotton is therefore treated, because cotton on its own is not flame resistant.

Durable is not the same as indestructible. The results on a fabric's certificate hold for the washing method and the number of washes its maker specifies. Where protection depends on a finish, as it does in treated fabric, stepping outside those conditions is a bigger risk than with inherent fabric. Two questions settle most choices: how, and how often, will the garment be washed, and after how many washes does the fabric's technical data sheet show it was tested?

Washing flame resistant clothing: softener, bleach and base layers

ASTM F2757 covers home laundering of flame resistant and arc-rated clothing, and ASTM F1449 covers industrial laundering; in practice the garment's care label is still the first reference. FR care instructions share a common list of products to avoid: chlorine bleach, hydrogen peroxide, fabric softener and any detergent that contains them. Most products sold as ‘oxygen’ stain removers are based on hydrogen peroxide or on percarbonate, which releases peroxide in water, so they belong in the same group.

Oil and fuel are a separate problem. Flammable liquid soaked into FR fabric acts as fuel in a flash, and a garment with oil or solvent contamination that laundering cannot remove is taken out of service. Heavily soiled items go in at the hottest temperature the label allows, the machine is not overloaded, and FR clothing is washed inside out and apart from everyday laundry. A low dryer setting, with garments taken out while slightly damp, limits shrinkage.

Shrinkage is not cosmetic. A garment that tightens sits against the body, loses the air gap between fabric and skin and becomes harder to strip off in an emergency. EN ISO 11612 caps dimensional change in washing at ±3% for woven fabric. A loose fit is part of the thermal protection.

The base layer rule is just as firm. NFPA 70E, the US standard for electrical safety at work, does not permit meltable fibres such as acetate, nylon, polyester, polypropylene and spandex in underlayers next to the skin. Wear cotton or FR base layers, and never put a non-FR jacket or fleece on top of FR clothing: if the outer layer burns, the FR garment underneath cannot prevent the injury on its own. Turkey's regulation on PPE use at work says the same in general terms, requiring equipment worn together not to undermine each other's protection.

How EN ISO 11612 relates to NFPA 2112

NFPA 2112 is the North American standard for flame-resistant garments that protect industrial personnel against short-duration thermal exposure from fire, which in practice means flash fire. The current edition is 2023. OSHA's 2010 enforcement policy for oil and gas drilling, well servicing and production points employers to NFPA 2112 and to NFPA 2113, which covers selection, care, use and maintenance.

The method differs from EN ISO 11612. Under NFPA 2112 the fabric must show no more than 100 mm (4 in) char length and 2 seconds afterflame in the vertical flame test, both as received and after 100 industrial launderings. Heat transfer performance must reach at least 25 J/cm² (6.0 cal/cm²) spaced and 12.6 J/cm² (3.0 cal/cm²) in contact, and the fabric may not shrink by more than 10% at 260 °C. The defining test is the manikin: a garment on a life-size, sensor-fitted manikin is engulfed in flame for 3 seconds, and predicted body burn must not exceed 50%. Compliance requires third-party certification.

Neither standard stands in for the other, and one certificate proves nothing about the other's tests. Some fabrics carry both. In Europe and Turkey, EN ISO 11612 is the reference standard for heat and flame; crews heading to the US or Canada, or companies whose specification comes from a North American head office, may need NFPA 2112 as well. Settle which one applies before the order, not after delivery.

What to put in a specification or quote request

In Turkey the employer decides which PPE is used on the basis of its risk assessment (Regulation on the Use of Personal Protective Equipment at Workplaces, Official Gazette 2 July 2013, No. 28695). The same regulation requires CE marking and user instructions in Turkish. Design and manufacture fall under the PPE Regulation published on 1 May 2019 (No. 30761), drafted in line with Regulation (EU) 2016/425; Category II and III PPE need an EU type-examination by a notified body.

If nobody knows the code yet, start by describing the heat source on site: what it is, how long people are exposed and how close they stand.

A quote request to Formasan that covers the points below puts the first fabric and pattern proposal in the right place and shortens the sampling round:

• The task and the hazard: welding process, the metal being poured (aluminium, or iron and steel) and the incident energy from the arc risk assessment.
• The exact standard and code line, for example ‘EN ISO 11612 A1 A2 B1 C1 E2 F1’, ‘EN ISO 11611 Class 2 A1’, ‘IEC 61482-2 APC 1’ or a minimum ELIM.
• Additional properties: antistatic for explosive atmospheres (EN 1149-5) and high visibility for road and site work (EN ISO 20471).
• Fabric preference and laundering: inherent or treated, home washing or industrial laundry, and an estimate of washes per year.
• Documents required: EU type-examination certificate, test report and user instructions in the local language.
• Anything added later, such as logos, name tapes or reflective tape, which must not compromise the garment's protection class.