BSS 7238 Smoke Density Test

The BS 7238 smoke density test is an important tool for evaluating the fire safety properties of materials, as smoke can often be more harmful than flames in a fire. The test provides a measure of the amount of smoke that material will generate when exposed to heat, allowing for the comparison of different materials and the selection of materials that are less likely to generate large amounts of smoke in the event of a fire.

Last Updated: September 18th, 2023 First Published :


Why Do BSS Tests Exist?

The Boeing Safety Standard, or BSS testing, is a technique for evaluating the gasses produced during combustion by particular materials. Materials that catch fire release gasses that, in some concentrations, could be harmful to people. To assess the safety of various materials, this test identifies and quantifies those harmful gasses.

By burning sample pieces of materials in a controlled environment, BSS testing identifies which harmful gasses are emitted and how much of each gas is created. The most used technique for determining the toxicity levels of the gasses is spectrophotometry. Since each molecule uniquely absorbs light, this method uses the way each compound absorbs light to determine what compound is there and in what quantity.

BSS examinations look for gasses like:

  • Carbon dioxide (CO)
  • Carbon monoxide (HCN)
  • Sulphur dioxide (HCL)
  • Hydrogen chloride (HF)
  • Hydrogen fluoride (HF)
  • Nitrogen oxides (NOx)
  • Hydrogen cyanide (HCN)

Similar tests are utilized in the government and railway industries as well as most frequently as a fire test for aeroplane materials. The purpose of BSS testing is to identify the properties of materials that cause smoke to be produced during combustion to assess their suitability for these sectors.

What Is Tested by BSS 7238?

Smoke density testing for aviation materials is done according to Boeing Safety Standard 7238. By recording the attenuation of a light beam through the smoke, it calculates the specific optical density of smoke created by burning aircraft material. Samples are placed in a smoke-density chamber that is closed and subjected to either radiant heat alone or radiant heat with a flame during this examination. The tester measures the light transmittance values to ascertain the optical density of the smoke while the substance goes through either flameless disintegration or blazing combustion.

To pass the test, the smoke produced must not exceed a certain smoke optical density value. Depending on the requirements of the evaluation, a different smoke density value will be needed.

The fire response of materials used in aeroplanes of the Boeing type is the focus of BSS 7238 smoke density testing. Plastic goods, wire ropes, non-metallic materials, and other like items will all be tested. Sample pieces may comprise wall panels, partitions, huge cabinet walls, and galley structures. The materials evaluated are ones frequently seen in passenger-occupied aircraft compartments.

Testing Requirements for BSS 7238

The BSS 7238 test must meet the following conditions:

  • a sample measuring 3 by 3 inches
  • at least three samples
  • The sample thickness must match the original component’s thickness.
  • A second set of samples might be used to determine whether the material response differently depending on which way it is cut.
  • The sample could either be a segment cut from a manufactured part similar to the ones placed in the aircraft or a part designed to mimic the component that is installed.
  • Testing needs to be done using sandwich panels and other constructed items.
  • Standards and Tests Related to
  • Another flammability test, the BSS 7239, is connected to the BSS 7238 test. The BSS 7239 gauges the smoke toxicity of composites, fabrics, and coatings used in the railroad, aerospace, and other government-related industries. Parts per million criteria must be met by materials used in these applications.
  • The results of this test reveal the volume of gasses released during the burning of a substance.

The ASTM E662 test, which also measures smoke density, is the basis for the BSS 7238 test. The flammability test ASTM E662 is frequently necessary for coatings and polymers used in the construction, railroad, and military sectors.

Video 01:Smoke Density Test Apparatus | Smoke Density Test Method | Smoke Density Test |Smoke Density Tester

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