Smoke and Corrosive Gas Tests

As with flammability, tests play a key role in studies of smoke formation from burning polymers. A wide variety of tests have been used, often in conjunction with flammability tests. Hirschler has given a brief description of most of the main tests [12]. 

Until recently, one of the main tests was the National Bureau of Standards (NBS) smoke chamber (ASTM E662) [13]. In this test, a vertical sample is decomposed under radiant heat in a sealed cabinet and the build up of optical density is monitored. The test can be run under both smouldering and flaming conditions, depending on whether a pilot ignition flame is present. 

Various parameters can be obtained from the NBS test. Those usually quoted are maximum optical density, time to maximum density, the time to reach an optical density of 16 (the critical observation time) and the optical density after 4 minutes. The critical observation time is an indication of how long before visibility would become too bad to allow one to find a way out of a room, while the density at four minutes is relevant to whether smoke would affect escape from, say an aircraft, before other life threatening aspects of a fire became important. 

smoke measurements are more and more being obtained by cone calorimetry as described in Section 6.3.5. 

Various corrosion tests are in use, often based on absorbing combustion or pyrolysis gases in water and determining the pH. In one test the effect of combustion gases on the electrical resistance of a printed circuit hoard is determined. Again, corrosion data can be obtained from the cone calorimeter. 

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