Fire Performance Analysis of PVC and Cabtyre Cables Based upon the Ignition Characteristics and Fire Growth Indexes

The ignition characteristics and fire growth indexes of the PVC cable (Cable 1), the flame retardant PVC cable (Cable 2), the cabtyre cable (Cable 3), and the cabtyre cable with fireproof coating (Cable 4), were investigated experimentally. Twenty experiments were conducted by cone calorimeter, and the ignition time and fire growth index under different external radiation heat fluxes were focused primarily. Results showed that the ignition time of Cable 2 was longer than that of Cable 1, and the ignition time of Cable 4 was longer than that of Cable 3. The critical heat flux, under which the cable could be ignited for any length of time, was derived through data fitting. In the present study, the critical radiation heat fluxes for Cable 1–4 are 3.5, 9.5, 13.4 and 18.5 kW/m2. The ratio of peak heat release rate (HRR) to the time reached the peak HRR is defined as fire growth index. The fire growth index of Cable 1 is larger compared with that of Cable 2, and the fire growth index of Cable 3 is larger than that of Cable 4. The fire growth index of cables has well linear relationship with the external radiation heat flux in the present study.