What is Secondary Flame Resistant (FR) Protective Clothing?

Secondary single-use flame-resistant clothing is intended to be worn over primary flame-resistant protective clothing for several reasons:

  • It protects underlying primary FR clothing from wear, tear, and damage.
  • Primary flame-resistant clothing is often more expensive and intended for multiple uses, so protecting it helps extend its usage or “lifetime.”
  • It can help reduce harm to the individual by providing an extra layer of defense against thermal hazards.

What is the purpose of Secondary FR clothing?

Secondary FR clothing is designed to protect primary FR clothing worn underneath, and it provides an extra layer of protection against sparks, flames, and/or molten drips for the wearer. The protective clothing used should be selected after a hazard risk assessment is completed by a trained and qualified individual. A hazard risk assessment considers the end-user’s work activities or applications, as well as known and expected hazards.

Possible applications for secondary FR Clothing

The following applications often involve processes, materials, and/or handling of flammable or combustible materials. Certain paints, grease, oils, dust, and chemicals are flammable and should require end-users to wear flame-resistant clothing.

  • Chemical processing;
  • Hazardous materials remediation;
  • Pharmaceuticals operations;
  • Paint spraying;
  • Tank cleaning;
  • Laboratory operations;
  • Petrochemical operations;
  • Bulk chemical transfer/handling operations;
  • General manufacturing;
  • General maintenance;
  • Clean-up operations;
  • Industrial turnarounds;
  • Oil and gas manufacturing; and
  • Petrochemical applications

Definitions Related to Secondary FR Clothing

After-flame: When a material continues to burn after the ignition source has been removed.

After-flame time: The length of time a material continues to burn after the ignition source has been removed.

Char length: After the specified tearing force has been applied to the fabric, this measurement refers to the distance from the fabric edge that is directly exposed to the flame to the furthest point of visible fabric damage.

Compliance: An evidence-based determination that a product or service meets the requirements of a standard or regulation.

Conformity assessment: A demonstration that the specified requirements for a product, process, system, person, or body have been met.

Declaration of conformity: A statement by the manufacturer or supplier, based on a decision made after evaluation, that the requirements specified in a standard have been met.

Dripping: A material’s response to a flame, demonstrated by flowing of the polymer. Dripping is the formation of liquid droplets from the melted substrate material used in protective clothing resulting from flame contact or heat exposure.

Flame-resistance: The property of a material that prevents, terminates, or inhibits combustion after the application of a flaming or non-flaming source of ignition, with or without subsequent removal of the ignition source.

Flash fire: A sudden and intense fire caused by the ignition of a mixture of air and a dispersed flammable substance, which can be a solid, liquid, or gas. For example, combustible dust, a flammable chemical, or the vapors of a flammable liquid can cause a flash fire. Flash fires are characterized by a high temperature, a short duration, and a rapidly moving flame.

Garments: Clothing that includes but is not limited to coveralls, pants, shirts, and outerwear. A garment can be disposable (single-use) or reusable (multiple-use).

Melt: A material’s response to heat, resulting in flowing or dripping of the material.

Model: A term used to identify a group of items of the same basic design and components from a single manufacturer. A model is produced by the same manufacturing process(es) and quality assurance procedures that are covered in the declaration of conformity. For example, items 8048-M and 8048-L have the same model number, but they differ in size (-M = Medium; -L = Large).

Multiple use: Garments or items that are designed and intended to be worn multiple times.

Predicted total burn injury: In fire testing of clothing, this term refers to the manikin surface area that registers a predicted second-degree burn or a predicted third-degree burn based on readings from all thermal energy sensors. These burn predictions are expressed as a percentage.

Primary flame-resistant protective clothing: Protective clothing engineered for the primary purpose of protecting the wearer from flames and thermal hazards.

Protective clothing material: Refers to any material, or combination of materials, used in protective clothing to isolate and/or cover parts of the body from a known or potential hazard.

Sample: The amount of material or product to be tested that is representative of the item as a whole.

Secondary single-use flame-resistant protective clothing: Protective clothing designed to be worn over top of primary flame-resistant protective clothing without negatively affecting the burn injury protective levels of the primary flame-resistant (FR) clothing. Secondary FR clothing helps protect the underlying primary FR clothing, which is often more costly and intended for multiple uses. Secondary FR clothing also adds an extra layer of defense against thermal hazards such as sparks, flames, and molten drips.

Single use: Products or protective clothing items that are designed and intended by the manufacturer to only be worn once. Once damaged or contaminated, these items should be properly disposed of and replaced.

Specimen: The product or item that undergoes testing. In some cases, the specimen is also the sample.

Secondary FR Clothing Testing

Flame Resistance Test: ASTM D6413 tests the vertical flame resistance of secondary single-use flame resistant clothing. When tested in accordance with ASTM D6413, the materials used in the construction of the garment are to have an average char length of no more than 7 inches (178 mm) and an average after-flame time of no more than two seconds. Failure in either result (char length, after-flame time) constitutes a failure of the material. Furthermore, there should be no evidence of dripping or melting of the material.

For each test, a minimum of five specimens in each material direction (char length, after-flame time) should be used to calculate the average. The following results must be reported:

  • After-flame time and char length of each specimen tested
  • The calculated average of all specimens for char length and after-flame time
  • Observations related to the melting and/or dripping of each specimen tested


FR Testing References

ASTM D6413/D6413M, Standard Test Method for Flame Resistance of Textiles (Vertical Test), 2015

16 CFR 1610, Standard for the Flammability of Clothing Textiles, 2016

ANSI/ISEA 125, American National Standard for Conformity Assessment of Safety and Personal Protective Equipment, 2014

ASTM D3776/D3776DM, Standard Test Methods for Mass Per Unit Area (Weight) of Fabric, 2013

ASTM F1930, Standard Test Method for Evaluation of Flame-Resistant Clothing for Protection Against Fire Simulations Using an Instrumented Manikin, 2015

CAN/CGSB 4.2 No. 27.5, Textile Test Methods — Flame Resistance — 45° Angle Test — One-Second Flame Impingement, 2008

Learn more about International Enviroguard’s Secondary Single Use Flame-Resistant Coveralls