Radiant Apparatus Research Articles

Comparison of smoke component yields between room‐scale and bench‐scale experiments

SummaryA standard procedure is needed for obtainingaccurate values of the yields of fire effluent components that are associated with harm to people from a singleacute exposure to the effluent from a fire involving realistic commercial products. We compare yields of toxic gases generated by four bench‐scale apparatus to the yields from previously conducted room‐scale fires. The apparatus is the radiant apparatus in NFPA 269 and ASTM E 1678, the smoke density chamber in ISO 5659‐2, a controlled‐atmosphere version of the cone calorimeter (ASTM E 1354), and the tube furnace specified in ISO/TS 19700. The bench‐scale specimens were cut from the same products that were burned in the room‐scale tests: a sofa, bookcases, and household electric power cable. The yields of CO2 CO, HCl, and HCN were determined. The yields of other toxicants (NO, NO2, formaldehyde, and acrolein) were below the detection limits, but were shown to be of limited importance relative to the four measured gases. We developed a criterion of a factor of two for satisfactoryscale agreement. Using this, the yields from the modified cone calorimeter were the most promising, but still imperfect, match to the room fire yields. The results of this study provide an improved basis for obtainingaccurate combustion product yield data for fire hazard and risk modeling over what currently exists.

Comparison of the smoke toxicity of four vinyl wire and cable compounds using different test methods

AbstractFour vinyl wire and cable materials were tested using five smoke toxic potency test methods: the NBS cup furnace test (in its flaming and non‐flaming modes), the NIST radiant test, the NIBS IT50 test (also using the radiant apparatus) and the UPITT test. One of the materials is a standard poly(vinyl chloride) (PVC) flexible wire and cable material, used commercially for wire insulation. The three other materials tested represent a new family of vinyl thermoplastic elastomer alloys, which are advanced materials with good fire performance, particularly in terms of heat release and smoke obscuration. It was found that the smokes from all four materials are similar in terms of their toxic potencies, and that they are all within the ‘common’ range of toxic potency found. In particular, the toxic potencies of the smoke from the new vinyl thermoplastic elastomer alloys are not significantly different from those of other traditional vinyl wire and cable compounds. The results of the tests were also interpreted in terms of the toxicities and concentrations of the individual gases emitted. The fractional effective dose of the toxicants analysed was sufficient to account for the toxicity of the smoke for the NBS cup furnace and the NISt radiant test. It was not able to account for the toxicity found in the UPITT test. The adequacy of the test protocols themselves was also investigated. It was found that the UPITT and the NIBS IT50 method are inadequate for measurement of smoke toxicity. It was also found that the NIST radiant test protocol is the one most likely to lead to the smallest amount of future testing.