Standards and Testing Overview

The following segments provide a brief overview of the commonly cited standards and test methods for testing Personal Protective Clothing (PPC) against the thermal hazards associated with flame, heat, electric arc and hydrocarbon flash fire and chemical and molten metal splash. There are six segments noted as:

• Testing for Flame Resistance

• Exposure to Flash Fire

• Exposure to Electric Arc

• Exposure to Electric Arc and Flash Fire (Protective Rainwear)

• Protection Against Heat, Flame and Thermal Hazards (European Standards)

• European Standards (ENs)

Testing for Flame Resistance

Federal Test Standard (FTS) 191A, Federal Test Method 5903.1

The most commonly used test measure is FTM 5903.1 of US Federal Test Standard 191A. FTSM 5903.1 does not establish a standard – it only establishes a test method with a no pass/fail criteria. The ASTM equivalent of this test is D6413.

ASTM D6413

• This test method determines the response of textiles to a standard ignition source, deriving measurement values for afterflame time, afterglow time and char length.

• The vertical flame resistance, as determined by this test method, only relates to a specified flame exposure and application time.

• This test method maintains the specimen fabric in a static, draft-free vertical position and does not involve movement except that resulting from the exposure.

• This standard must be used to measure and describe the response of materials, products or assemblies to heat and flame under controlled laboratory conditions and shall not be used to describe or appraise the fire hazard or fire risk of materials, products or assemblies under actual fire conditions.

Testing Flame Resistance of Fabric

In an enclosed cabinet, twelve inch fabric specimens are vertically suspended in a holder with the fabric restrained on three sides. A controlled flame is impinged on the bottom cut edge of the fabric for twelve seconds. The flame is extinguished at the end of twelve seconds and three sets of data are recorded.

Recorded Test Data

• Afterflame – the number of seconds (in tenths of seconds) during which there is a visible flame remaining on the fabric.

• Afterglow – the number of seconds (in tenths of seconds) during which there is a visible glow remaining on the fabric.

• Char Length – the length of the fabric (in tenths of inches) destroyed by the flame that will readily tear by application of a standard weight.

Overall Results

Five fabric specimens in each fabric dimension (length and width) are tested. The individual results of the five specimens are averaged and reported as the test results.

Exposure to Flash Fire

NFPA 2112

Standard for Flame Resistant Garments for Protection of Industrial Personnel Against Flash Fire.

This standard specifies the minimum performance requirements and test methods for FR fabrics and components and the design and certification requirements for garments developed to protect workers from a flash fire hazard. It requires FR fabrics to pass a comprehensive number of thermal tests including the following:

• ASTM D6413 - Vertical Flammability Test - maximum 2.0 seconds afterflame and 4.0 inch char length.

• ASTM F1930 - Thermal Mannequin Test - maximum predicted body burn after 3.0 second thermal exposure.

• ASTM F2700 - Heat Transfer Performance (HTP) test - minimum HTP of 6.0 cal/cm² spaced and 3.0 cal/cm² contact.

• Thermal Stability Test - fabric must not melt or drip, separate or ignite after 2.0 minutes in a 260° C (500° F) oven.

• Thermal Shrinkage Test - fabric must not shrink more than 10% after 5.0 minutes in a 260° C (500° F) oven.

NFPA 2113

Standard on Selection, Care, Use and Maintenance of Flame Resistant Garments for Protection of Industrial Personnel Against Flash Fire.

This standard serves as a user's guide for industrial FR clothing. It addresses topics such as hazard assessment, purchasing, cleaning, repairs, storage, decontamination, retiring garments and proper use procedures. This standard requires that garments be certified NFPA 2112.

NFPA 2112/2113 Standards

These standards specify design, performance, certification requirements and test methods for flame resistant garments for use in areas at risk from flash fires. Third party certification is required. NFPA 2112 sets a flame resistant requirement of less than or equal to 4.0 inches of char length damage.

• NFPA 2112 test exposure is set at 3.0 seconds.

• CGSB and NFPA define a flash fire as "typically 3.0 seconds or less."

• NFPA 2112 sets failure above 40% of predicted body burn. For a garment to pass NFPA 2112 testing, it must exhibit 40% or less total predicted body burn using a standardised burn injury model.

• Under NFPA 2112 all flame resistant clothing must not melt, drip or exhibit afterflame burning.

Flame Resistance

Each fabric layer is required to be tested as received and after 100 cycles of washing and drying and/or dry cleaning.

Thermal Protective Performance (TPP)

The TPP is the amount of heat it takes to pass through the fabric and cause a second-degree burn when a person is wearing a fabric. The higher the TPP, the more protective the fabric. The passing criteria for NFPA 2112 is a minimum TPP of 6.0 cal/cm² when tested in a spaced configuration and a minimum TPP of 3.0 cal/cm² in the contact configuration.

Heat Transfer Performance (HTP)

The HTP is the amount of heat it takes to pass through the fabric to cause second-degree burns based on the skin burn curve. NFPA 2112 requires a fabric to have a minimum of 6.0 cal/cm² when tested with a spacer and 3.0 cal/cm² in contact.

Fabric must be tested both with the fabric specimen in contact with the sensor assembly and separated from the sensor by a ¼ inch spacer. A minimum TPP/HTP of 6.0 cal/cm² is required for spaced and 3.0 cal/cm² for contact tests.

NFPA 1975

Standard on Station/Work Uniforms for Emergency Services

This standard outlines the requirements for the design, performance, testing and certification of non-primary protection station and work uniforms. It also includes performance requirements for both non-FR and FR fabrics and garments, including heat and thermal shrinkage, thermal stability, seam strength and label durability. The optional FR station wear must meet the non-FR requirements as well as the flammability testing of the fabric and other small textile components.

Standard requires:

• Approval by third party listing organisation.

• Certified garments must not ignite, melt and drip or separate in a forced air oven test.

• FR or untreated 100% Cotton or Wool fabrics are acceptable.

CGSB 155.20.2000

Work Wear for Protection Against Hydrocarbon Flash Fire.

In addition to flame resistance, heat resistance and thermal shrinkage requirements, this standard also requires that the garment label be in English and French. For single layer garments, the TPP values for both spaced and contact tests must be reported on the garment label.

Profile of a Flash Fire

• Temperature in excess of 800° C (1470° F).

• Heat fluxes up to 4.0 cal/cm².

• 2.0 to 5.0 seconds in duration.

• Heat exposure energies up to 20 cal/cm².

Exposure to Electric Arc

ASTM F1506

Standard Performance Specification for Flame Resistant and Arc Rated Textile Materials for Wearing Apparel for Use by Electrical Workers Exposed to Momentary Electric Arc and Related Thermal Hazards.

This specification provides performance requirements for clothing worn by electric utility workers and other personnel working around energised parts. In addition to non-thermal requirements, the standard requires the fabric to be FR. FR here is measured using ASTM D6413 Vertical Flame Test (maximum 2.0 seconds afterflame and 6.0 inch char length). The arc rating is either Arc Thermal Performance Value (ATPV) or Arc Break-open Value (E_bt) as measured by the ASTM F1959-06ae1 Arc Thermal Performance Test.

The standard has a general requirement that thread, findings and closures do not contribute to the wearer’s injuries in an electric arc exposure. Knit or woven fabrics may not melt and drip or have more than 2.0 seconds afterflame or 6.0 inches char length. Arc ratings must appear on garment labels.

NFPA 70E

This standard addresses electrical safety-related work practices for employee workplaces. These safety measures are necessary for the practical safeguarding of employees relative to the hazards associated with electrical energy during activities such as installation, inspection, operation, maintenance and demolition of electrical conductors, electric equipment, signalling and communication conductors and equipment and raceways. This standard also includes safe work practices for employees performing other work activities that can expose them to electrical hazards. 

NFPAE 70E Requirements

The FR fabric and garment requirements are those shown in ASTM F1506. Tables of common electrical tasks are included and assigned one of five PPE Categories (0, 1, 2, 3 or 4). Each PPE Category has a minimum arc rating for protective clothing measured in cal/cm² plus other PPE requirements.

Employers must use safe work practices and PPE which includes arc rated clothing based upon the incident energy associated with the specific task. Total system arc rating of layered ensembles must be determined by a multilayer arc test. If PPE is selected using the NFPA 70E tables, all layers used to determine the total system arc rating must be flame resistant. Employers must document an overall safety program including hazard/risk assessment and job briefing procedures which must be audited annually. For layered systems, arc ratings cannot be added together. Each ensemble must be tested layered as it will be worn. CSA Z462 is the Canadian standard for electrical workplace safety. As currently written, the PPE requirements are virtually identical to NFPA 70E.

ASTM F1958 Electric Arc Testing

Determines the probability of ignition at a range of arc exposures. Used to test FR and non-FR materials. Fabrics are tested as shirts mounted on mannequins.

ASTM F1959-99 Electric Arc Testing

Determines arc rating of materials based on electric arc exposure. Fabrics are mounted on flat panels for testing. Ratings are expressed in cal/cm². The E_bt is determined if material shows break-open response above the ATPV.

Occupational Safety & Health Administration (OSHA) 1910.269 Standard for Electric Power, Transmission and Distribution

This standard covers the operation and maintenance of electric power generation, control, transformation, transmission and distribution lines and equipment. The provisions apply to:

• Power generation, transmission and distribution installations including related equipment for the purpose of communication or metering, which are accessible only to qualified employees.
  

• The types of installations covered by the provisions include generation, transmission and distribution installations of electric utilities as well as equivalent installations of industrial establishments. Supplementary electric generating equipment that is used to supply a workplace for emergency, standby or similar purposes only is covered under Subpart S.

Exposure to Electric Arc and Flash Fire (Protective Rainwear)

ASTM F1891

Standard Specification for Arc and Flame Resistant Rainwear

Applies to rainwear for use by workers who may be exposed to thermal hazards of momentary electric arcs and open flames.

ASTM F2733

Standard Specification for Flame Resistant Rainwear for Protection Against Flame Hazards.

Establishes the requirements for workers exposed to industrial hydrocarbon fires or other petrochemical fire and thermal hazards.

ASTM F1891/F2733

Both standard specifications establish applicable test methods, minimum physical and thermal performance requirements, suggested sizing charts and suggested purchasing information for rainwear.

• Material must withstand 30 PSIG water pressure without leaking.

• Seam hydrostatic resistance requirement is 3 PSIG for 2 minutes.

• No melt and drip is permitted in vertical FR testing. Maximum allowable char length is no more than 4.0 inches for F2733 and 6.0 inches for F1891.

• For rainwear for protection from electric arcs, the arc rating (either ATPV or E_bt) must be equal to or greater than 5.0 cal/cm². The material response characteristics are evaluated at the arc rating and no dripping is permitted at twice the exposure level of the arc rating.

• Rain wear for protection from hydrocarbon fires and related hazards must have an average predicted total burn area equal to or less than 40% when exposed to a 3.0 second simulated flash fire.

• Garments meeting the requirements of F1891 and/or F2733 must be labelled with a statement that the garments conform to the specification, the manufacturer’s name, style designation, size information, care instructions and fibre content. Garments for protection from electric arcs are required to be labelled with the arc rating (ATPV or E_bt) of the base material.

ANSI Standard 107 (American National Standard for High Visibility Safety Apparel and Head Wear Devices)

This standard specifies performance requirements for high visibility safety apparel and head wear PPE. For the purpose of this standard, the term ‘garment’ shall be used to mean apparel and head wear PPE. These garments are intended to provide conspicuity to the user in hazardous situations under any light conditions by day and under illumination by vehicle headlights in the dark. Performance requirements are included for colour, reflection and minimum areas, as well as the recommended configuration of the materials. Performance requirements are also provided for the physical properties of background materials used in the construction of high visibility safety apparel and head wear. Test methods are provided in the standard to help ensure that a minimum level of visibility is maintained when garments are subjected to ongoing care procedures.

Organisation References

ANSI – American National Standards institute
ASTM - American Society for Testing and Materials
CGSB – Canadian General Standards Board
FTSM – Federal Test Standard Method
NFPA - National Fire Protection Association. NFPA documents may be cited by any government level and therefore take on the force of law.

Protection Against Heat, Flame and Thermal Hazards (European Standards)

EN ISO 11612:2008 Protective Clothing to Protect Against Heat and Flame

European requirements for workers exposed to heat and flame.

This standard replaces EN 531:1995 however protective garments which have an EN 531 certification remain valid.

• The standard specifies the performance requirements for garments which protect the body from heat and flame (except the hands).

• The standard is not applicable for fire fighters (EN 469) and welders (EN 470 - EN ISO 11611).

• EN ISO 11612 tests the whole fireproof garment, not just the fabric used to produce it. This is to stop the influx of sub-standard flameproof protective clothing flooding the market.

• The standard tests finished garments, so now fabric, design specifications and garment features, such as seams must also comply.

• EN 11612 now includes an F Code for contact heat.

• Flame spread for EN 11612 is tested before and after laundering.

• Standard EN 531 used to test only the flame spread after 5 cycles, but with the new standard EN 11612 all of the tests are made after 5 laundry cycles.

• Each wash cycle is now followed by drying, so for example, 100 washes goes through 100 dry cycles. Prior to this the garments were only dried after the final wash.

The following test parameters are used:

Flame Spread EN 532:1992

A single layer or multi-layer system is tested by face ignition. Limited spread of flame of the specimen is determined when a calibrated flame is applied to the surface of the vertically oriented specimen for 10 seconds.

Pass A1 (surface ignition), Pass A2 (edge ignition) - no flaming to the top or edge, no hole formation, no flaming or molten debris, mean afterflame time ≤ 2 seconds, mean afterglow time ≤ 2 seconds.

Convective Heat EN 367:1992

Heat transmission through FR clothing depends on the thickness, type of fibres used and the textile's composition (blend, weight). Air gaps between layers (with undergarments or in multi-layer systems) can also affect heat transmission. In this test, a horizontally oriented specimen is subjected to a gas flame from a gas burner beneath it. The heat passing through the fabric is measured by means of a calorimeter. The rise in temperature to 24° C/75° F (HTI 24) is recorded in seconds for classification.

Classification Level B (B1>B5)

Radiant Heat EN 366:1993

A thermal sensor is mounted behind and in contact with the specimen, which is in front of a radiator. The rise in temperature (as recorded by the sensor) over time at a given level of incident radiant source is measured. Time for reaching threshold of pain (t1) and second-degree burn (t2) is calculated for classification. The following classifications are performed:

• Changes in appearance of fabric, for example, shrinkage, charring, discolouration, scorching, melting, dripping and glowing.

• Heat transfer levels (t1, t2) and heat flux (t3).

• Heat transmission factor - a measure of the fraction of heat transferred through a specimen.

Classification Level C (C1>C4)

Molten Metal Splash EN 373:1993

Single layer and multi-layer fabrics are tested by pouring measured quantities of molten metal at a specific angle onto the test specimen. The damaged is assessed by placing a PVC film (having similar qualities to human skin) underneath the test specimen and noting damage after pouring. Any adherence of metal to the specimen is noted. Classification is done on the basis of the minimum quantity of molten metal required to cause damage to the PVC film. Aluminium, copper, iron and soft steel can be used as test metals.

Contact Heat ISO 12127-1:2007

Clothing for Protection Against Heat and Flame - Determination of contact heat transmission through protective clothing or constituent materials - Part 1: Test method using contact heat produced by heating cylinder.

ISO 12127-1:2007 specifies a test method for the determination of contact heat transmission. It is applicable to protective clothing (including hand protectors) and its constituent materials intended to protect against high contact temperatures.

Application of ISO 12127-1:2007 is restricted to contact temperatures between 100° C and 500° C.

Arc Thermal Performance Value (ATPV)

EN 61482-1-2:2007 - Protective Clothing Against Thermal Hazards of Electric Arc

The arc rating is most commonly quantified by the Arc Thermal Performance Value (ATPV) determined by the open arc test method IEC 61482-1. This test method is currently being revised to IEC 61482-1-1/CDV.

The ATPV represents the maximum incident thermal energy in units of energy per surface area, for example, kJ/m2 or cal/cm², that a fabric can support before the wearer will suffer second-degree burns. The break-open threshold energy (E_bt) is another fabric characteristic. It represents the highest incident energy exposure value on a fabric where the garments do not exhibit break-open. The formation of holes in the fabric caused by break-open would allow heat or flames to pass through. Workers are assumed safe if the arc rating of their clothing (ATPV value) exceeds the electric arc incident energy as calculated in the worst case scenario of a risk assessment.

The box test is another way to measure the protective performance of clothing against the thermal effects of an electric arc and is defined in the IEC 61482-1-2 test method. In this test, the fabric is exposed to an electric arc confined in a specific box with a specific electrode arrangement.

A fabric passes the test if:

• The heat transferred behind the fabric does not cause second-degree burn (that is, is below the Stoll curve).

• The afterflame time is below 5 seconds.

• There is no melting to the inner side of the fabric.

• A hole caused by the arc is not larger than 5 mm in every direction (in the inner most layer).

Test conditions for Class 1 try to simulate typical exposure conditions for a short circuit current of 4 kA protected by devices limiting the duration of the arc to 0.5 seconds in confined space and of 7kA respectively for Class 2.

Electric arc protective clothing can receive IEC 61482-2/CDV certification if one of the following requirements is met:

• The ATPV value of the clothing must be at least 4 cal/cm².

• The clothing has to pass at least the electric arc box test Class 1.

Recommendations:

• That all layers are made of inherently flame resistant materials.

• Inappropriate underwear could ignite or melt, thus having an adverse effect on protection and aggravating the outcome of an electric arc incident.

EN 13034:2005 Type PB* [6] (*PB: Partial Body Protection)

Protective Clothing Against Liquid Chemicals – Limited Protective Performance

This standard specifies the performance requirements of garments offering limited protective performance against liquid chemicals and covers garments for intended use in cases where there is potential exposure to low volume splashing. Garments should be suitable for use in situations where there is exposure to small quantities of liquid chemicals but not where a complete permeation barrier is required.

Overview of EN ISO 11612:2008 - Protective Clothing to Protect Against Heat and Flame

Heat transmission performance requirements:

European Standards (ENs)

A European Standard (EN) is one which has been adopted by one of the three recognised European Standardisation Organisations (ESOs): CEN, CENELEC or ETSI. A standard is produced by all interested parties through a transparent, open and consensus based process. European Standards are a key component of the Single European Market. Although rather technical and often unknown to the public and media, they represent one of the most important issues for businesses. Often perceived as boring and not particularly relevant to some organisations, they are actually crucial in facilitating trade and hence have high visibility among manufacturers inside and outside Europe. A standard represents a model specification, a technical solution against which a market can trade. It codifies best practice and is usually state of the art.

Directive 89/686/EEC on personal protective equipment is EU law. Standards are not legislated; however they provide technical translation of the essential requirements of the PPE Directive.