New data on the toxicity of thermal decomposition products from flame-retardant cable insulation

Introduction. Experimental studies of the toxicity of the thermal decomposition products of the insulation of non-combustible electrical cables are relevant due to the lack of specific coefficients for the formation of toxic gases, which are necessary for fire-technical calculations.

Goals and objectives. The purpose of the paper is to obtain new experimental data on the specific coefficients of formation of an extended list of toxic gases that are formed during the thermal decomposition of the insulation of non-combustible cables. To achieve this goal, experiments were conducted in a small-scale experimental setup to determine the fire hazard of condensed materials in the case of thermal decomposition of the KVVGng(A)-LS 4 × 1.5 electric cable.

Methods. Measurement of the partial densities of toxic gases and oxygen, as well as the specific mass burn-out rate of cable specimens in a small-scale pilot plant. Processing of experimental data and analysis of the obtained results.

Results and discussion. It was found that during the thermal decomposition of the cable specimens under test, a mixture of toxic gases (carbon monoxide and dioxide, hydrogen chloride, hydrogen cyanide, phosgene, nitrogen dioxide, and acrolein) is formed, which is not taken into account in fire-technical calculations.
The dependence of the partial densities of oxygen and the above-mentioned toxic gases, the specific absorption coefficient of oxygen, and the specific formation coefficients of toxicants, as well as the specific mass rate of combustion of the specimens, on the test time was obtained.
To account for the scale factor (the difference in size between the small-scale experimental setup and the real room), the partial densities of toxic gases were plotted against the change in partial density of oxygen.
The analysis of the results showed that the partial densities of toxic gases exceeded or were comparable to their critical values for humans.

Сonclusion. The new experimental data on the specific coefficients of formation of the above-mentioned toxic gases can be used in the calculation of fire risks in rooms where non-combustible cables are used or manufactured.

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