The risk of textiles catching fire is a significant factor contributing to fatalities in fire incidents. To enhance safety, especially in clothing, it’s crucial to implement accurate flammability standards and test fabrics for flame resistance.
These measures aim to reduce the chance of injuries and deaths during a fire.
Testing the flame retardant properties of fabrics not only ensures safety but also helps manufacturers improve their products.
Different environments and applications require specific tests, so understanding these differences is essential.
This article explores the common tests used to evaluate how well a fabric can resist catching fire.
Flame Retardant Fabric Classification
Fabric is categorized variably according to its fire retardant properties. For instance, a fabric certified to be flame retardant is topically treated with a chemical after its weaving process. Natural fibers like cotton are categorized as flame retardant when topically treated with fire retardant chemicals. However, topical treatments can wear out over time, particularly if regularly cleaned.
Another category is permanently flame retardant fabrics. These are the fabrics that are woven from non-combustible fibers, and their fire retardant characteristic will last for the fabric’s life. Even if the fabric is cleaned, its fire retardant properties will not dissipate.
Flame-Retardant Test for Fabric
Fabric flame retardant test methods vary in terms of purpose, equipment, and principles, and it is hard to compare the results of the various methods. However, in any case, the tests are intended to measure the fabric’s flammability when it is exposed to a certain flame source. The flame retardant certification is provided after the conduction of the tests to endorse that the fabric has passed certain criteria and is safe for use in different environments.
Flame retardant testing can be confusing for customers, particularly if they do not have the know-how of flame retardant criteria. To make it easier, here are a few tests conducted specifically for protective garments usually worn in the industrial setting.
Flame Retardant Clothing standards
Clothing that doesn’t easily catch fire must meet certain standards.
One main standard is NFPA 2112, which ensures garments protect against intense fires often found in industries like oil and gas.
Another important standard is NFPA 70E, which ensures clothes guard against hot electric arcs common in welding.
NFPA 70E allows companies to declare their compliance themselves, whereas NFPA 2112 needs approval from an independent organization.
Vertical Combustion Test Method for protective clothing
The vertical flame test is done to specify the garment’s protection level against heat and ignition. It is based on the fabric’s burning rate and determines the standard it must meet to provide protection when it is presented with fire in a vertical flame test. The textile product that meets the standard requirement is considered to be flame retardant.
For this test, every individual layer of the group is tested separately. If the fabric tag specifies that the fabric must be washed, then the fabric needs to be tested before and after at least a hundred washing and drying cycles. The standard time for flame exposure for this test is twelve seconds.
Once the fabric is exposed to flame and cooled down, an appropriate amount of weight is hung to provide an adequate amount of tearing force. The material and the reflective tape usually used in fire retardant garments must have a charred length of around four inches, and the post-burning duration must not be more than two seconds. Moreover, the fabric must not drip or melt.
To conduct the test, a fabric sample of a certain size is vertically placed in a combustion test chamber and is ignited for twelve seconds via a pre-specified ignition source. Once the source is removed, the fabric’s protraction and burning time are measured. Once the smoldering stops, the fabric’s charred or damaged length is measured per the stated method. The vertical combustion method is usually used to ascertain the flame retardant characteristics of garments, decorative fabric, tent fabric, etc.
Fabric Flame Retardant Testing Via Special Equipment
Another method through which manufacturers can test the flame retardant properties of textiles involves the use of special equipment. A flame retardant box is used that is suitable for testing the flame retardant characteristics of garments, tents, or decorative fabric. This method is usually employed in scientific research departments, the rubber industry, or textile inspection units.
The flame retardant box is designed to conform to a set of standards outlined for the vertical combustion performance test for textiles and also the standards for fire-blocking materials.
The box used an electrical heating wire ignition and automatically records the fabric’s burning continuation time after exposure to ignition and its flame retardant time.
The timing for the ignitor is set anywhere between 0 and 100 seconds, but the standard is twelve seconds. Moreover, the height of the flame can be adjusted while the temperature gauging device can also be configured.
The Test Method for Protective Clothing Used in Welding and Similar Processes
Clothes used in welding or similar jobs are checked to ensure their effectiveness against fire. These tests are done based on minimum safety standards the fabric needs to maintain.
Such protective gear helps guard against bursts of hot metal and burning heat due to electric arc use in welding. This testing is vital where only brief touches with flames occur.
These approved protections help reduce electric shock dangers in situations where parts might contact electric conductors with voltages reaching up to about 100 volts.
Different test types provide safety from flames, intense heat, and bits of molten metal. Detailed tests also assess the fabric’s electrical resistance, strength, and how much pressure it can withstand.