Plastic has become a ubiquitous part of life. Due to its strong but lightweight qualities, plastic is used in literally thousands of consumer products ranging from automobile components, residential and commercial building products, packaging, electronic components, and much more.

Because plastic is a combustible material, testing plastic materials for Flammability—or Reaction to Fire—is a crucial step in strengthening consumer confidence. Manufacturers of plastic products or those who utilize plastic components must assure consumers that their products are reasonably fire-safe and that their brand is a trusted resource for goods. Using an accredited testing lab is one important way to show that your products live up to industry standards and protect against unnecessary injury or death.

In addition to providing consumer confidence, manufacturers of plastic products often must demonstrate compliance with applicable safety codes, standards, and regulations. Consumer goods are most commonly tested against fire test standards written by nationally-recognized Standards Development Organizations such as ASTM International, UL, or the National Fire Protection Association (NFPA), among others.

When discussing fire tests, the test lab will first determine the necessary standards required for a particular plastic product, perhaps based on its intended end-use. The standards are designed to test specific properties, so products may be subject to multiple tests that measure or rate various characteristics, such as the following:

  • Resistance to fire – measurement of a product’s ability to resist catching on fire.
  • Ignition rate and/or flame spread – measurement of a product’s characteristics for fire expansion.
  • Reaction to fire – measurement of a product’s response when exposed to fire.
  • Smoke density – measurement of smoke generated in the presence of flame.
  • Decomposition – measurement of a product’s degradation when exposed to fire.
  • Afterflame – measurement of length of time for flaming to cease.
  • Afterglow – measurement of length of time for flaming and glowing to cease.
Smoke Development Chamber with vent
Smoke Development Chamber with vent

Depending on the product size and form, plastic materials can be tested using small-scale (or benchtop) fire tests. Specialized testing apparatuses are utilized by accredited testing labs to evaluate Fire Resistance and Reaction to Fire characteristics on a variety of products. Additionally, all plastic building products to be approved for outdoor use in Miami-Dade County, Florida must be tested for ASTM D635 rate of burn, ASTM D2843 smoke density, and ASTM D1929 self-ignition temperature, as well as undergo 4,500 hours of ASTM G155 xenon arc weathering exposure (or 5 years of outdoor exposure in Southern Florida).

Vertical Tube Furnace
Vertical Tube Furnace

Following is a list of several common small-scale benchtop fire tests:

  • ASTM D635 – Standard Test Method for Rate of Burning and/or Extent and Time of Burning of Plastics in a Horizontal Position – Utilizing a rate of burn apparatus, material is given a value based on rate of burning or extent and time of burning characteristics, or both. This fire-test-response test method covers a small-scale laboratory screening procedure for comparing the relative linear rate of burning or extent and time of burning, or both, of plastics in the form of bars, molded or cut from sheets, plates, or panels, and tested in the horizontal position. (ASTM, n.d.).
  • ASTM D1929 – Standard Test Method for Determining Ignition Temperature of Plastics – This test utilizes a vertical tube furnace to assign a value that represents the lowest temperature that will cause ignition of the material. This test is not intended to be the sole criterion for fire hazard. In addition to ignition temperatures, fire hazards include other factors such as burning rate or flame spread, intensity of burning, fuel contribution, products of combustion, and others. (ASTM, n.d.).
  • ASTM D2843 – Standard Test Method for Density of Smoke from the Burning or Decomposition of Plastics – This fire-test-response test method covers a laboratory procedure for measuring and observing the relative amounts of smoke obscuration produced by the burning or decomposition of plastics. It is intended to be used for measuring the smoke-producing characteristics of plastics under controlled conditions of combustion or decomposition. (ASTM, n.d.).
  • ASTM D3801 – Standard Test Method for Measuring the Comparative Burning Characteristics of Solid Plastics in a Vertical Position – This test method was developed for polymeric materials used for parts in devices and appliances. The results are intended to serve as a preliminary indication of their acceptability with respect to flammability for a particular application This fire-test-response standard covers a small-scale laboratory procedure for determining comparative burning of solid-plastic material, using flame applied to the base of specimens held in a vertical position. (ASTM, n.d.).
  • ASTM D4804 – Standard Test Method for Determining the Flammability Characteristics of Nonrigid Solid Plastics – This fire-test-response test methods describe small-scale laboratory procedures for determining the comparative burning characteristics of solid plastic materials that, due to specimen thinness and nonrigidity, distort, shrink, and/or are consumed up to holding clamp when tested using Test Method D3801. A flame is applied to the base of specimens held in a vertical position and the extinguishing times are determined upon removal of the test flame. (ASTM, n.d.).
  • ASTM D4986 – Standard Test Method for Horizontal Burning Characteristics of Cellular Polymeric Materials – This test method provides a means of measuring the time and extent of burning for cellular polymeric materials. It also provides a means of measuring burning rates for materials that continue to burn past the specified gage marks. This fire-test-response standard contains a test method for small-scale laboratory procedures to be used to determine the relative rate of burning and the extent and time of burning of horizontally oriented cellular polymeric materials having a density less than 250 kg/m3. (ASTM, n.d.).
  • ASTM E136 – Per ASTM E136, “this test method uses a furnace to expose building materials to a temperature of 750°C (1382°F) until failure occurs or for at least 30 minutes… While actual building fire exposure conditions are not duplicated, this test method will assist in indicating those materials which do not act to aid combustion or add appreciable heat to an ambient fire.”
  • UL 94 – Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances – The UL standard includes four of the tests outlined above: ASTM D635, D4986, D3801, and D4804. These requirements cover tests for flammability of polymeric materials used for parts in devices and appliances. They are intended to serve as a preliminary indication of their acceptability with respect to flammability for a particular application. (UL, 2013).

If your products fall under the above-mentioned standards, small-scale benchtop testing via an accredited testing lab is a good solution for you. These tests are reliable and can provide valuable data about your products and how they perform under specified fire conditions. Knowing this information about your products not only demonstrates code compliance, but can assist in getting them to market faster, improve current manufacturing processes, gain a marketing advantage over competitors, and assist in developing new and innovative products for the marketplace.

ICC NTA provides both small-scale and large-scale tests for Fire Resistance and Reaction to Fire. For additional information, please see our fire testing page here or speak to an expert by calling ICC NTA at 574-773-7975. Our team is highly trained to guide you through the testing process, discuss expected timelines for conducting tests, and answer any other questions you may have regarding testing for Fire Resistance and Reaction to Fire.

References:
ASTM D635-18, Standard Test Method for Rate of Burning and/or Extent and Time of Burning of Plastics in a Horizontal Position, ASTM International, West Conshohocken, PA, 2018, www.astm.org

ASTM D1929-16, Standard Test Method for Determining Ignition Temperature of Plastics, ASTM International, West Conshohocken, PA, 2016, www.astm.org

ASTM D2843-16, Standard Test Method for Density of Smoke from the Burning or Decomposition of Plastics, ASTM International, West Conshohocken, PA, 2016, www.astm.org

ASTM D3801-19, Standard Test Method for Measuring the Comparative Burning Characteristics of Solid Plastics in a Vertical Position, ASTM International, West Conshohocken, PA, 2019, www.astm.org

ASTM D4804-19, Standard Test Method for Determining the Flammability Characteristics of Nonrigid Solid Plastics, ASTM International, West Conshohocken, PA, 2019, www.astm.org

ASTM D4986-18, Standard Test Method for Horizontal Burning Characteristics of Cellular Polymeric Materials, ASTM International, West Conshohocken, PA, 2018, www.astm.org

UL 94, Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances, UL LLC, Northbrook, Illinois, 2013, https://standardscatalog.ul.com