Density of Smoke from the Burning or Decomposition of Plastics
ASTM D2843 Smoke Density Test, also known as the Exit Sign Smoke Test, is intended to be used for measuring the smoke-producing characteristics of plastics under controlled conditions of combustion or decomposition. The measurements are made in terms of the loss of light transmission through a collected volume of smoke produced under controlled, standardised conditions. This test is used by model code organisations in controlling the use of plastic materials in light transmitting applications. It can be used as an alternative to the ASTM E84 smoke measurement test because this test method can readily be performed on thermoplastic materials that may drip and fall out of the E84 test apparatus. Other smoke test apparatus, for example, ASTM E1354 Cone Calorimeter, E662 Smoke Density Chamber etc. are also available at FTT.
FTT Exit Sign Test Apparatus ASTM D2843:
The FTT Exit Sign Test is designed for the measurement and observation of the smoke-producing characteristis of plastics under controlled conditions of combustion or decompisition according to ASTM D2843-10 but not to be used for measuring any other characteristics of the plastic combustion.
The apparatus consists of:
- Combustion Chamber
- Specimen Holder
- Ignition System
- Photometric System
- Control Unit (incl. Smoke Meter
The test specimen is exposed to flame for the duration of the test and the smoke is substantially trapped in the chamber in which combustion occurs. A 25mm x 25mm x 6mm specimen is placed on a supporting metal screen and burned in the test chamber, under active flame conditions, using a propane burner operating at a pressure of 276 kPa (40 psi). The 300mm x 300mm x 790mm test chamber is instrumented with a light source, photoelectric cell and meter to measure light absorption horizontally across the 300mm light beam path. The chamber is closed during the 4 minute test period, except for the 25mm high ventilation opening around the bottom of the chamber.
Measurement is by means of transmitting a beam of light through the smoke generated by the sample under test to a light measuring receiver. Results obtained are in units of light absorption (%). The light absorption data are acquired by a user-friendly software tool and are plotted versus time. Two indexes, the maximum smoke produced and the smoke density rating, are used to rate the material. A heat resisting glass door is fitted to allow observation of the test whilst it is in progress.