Experimental Study on Flammability and Flame Spread Characteristics of Polyvinyl Chloride (PVC) Cable

Abstract

Polyvinyl chloride (PVC) is widely applied in cables as insulation materials, which are vital for operation and control of industrial processes. However, PVC cables fires frequently occur, arousing public concern. Therefore, experimental methods are used to study flammability and flame-spread characteristics of PVC cable in this paper. Influences of cable structure and number are investigated, which is scanty in previous works. As cable core number of single cable or cable number of multiple cables rises, average flame height and width increase while the increment decreases. Formulas concerning dimensionless flame height and single cable diameter (or total width of multiple cables) are obtained. The former is negatively correlated with the latter. For single cable, convective heat transfer is dominant, and flame-spread rate decreases as cable core number increases. Cable maximum temperature, which drops first and then rises as cable core number increases, is observed in the cable core area. For multiple cable, the flame-spread rate increases as cable number increases. As the cable number rises, the length of pyrolysis and combustion zone increases while the maximum temperature of cable surface decreases. This work is beneficial to fire hazard evaluation and safety design of PVC cables.

An experimental study on the combustion process and thermodynamic characteristic parameters of copper wire overcurrent fault

“…Yu et al 5 simulated the critical condition of five times of overcurrent and studied the thermal characteristics of the insulating layer, the microstructural characteristics of the weld trace, and the macroscopic characteristics of the 2.5 mm 2 copper wire, which reflected the characteristics of the fire traces under the overcurrent condition; Gao et al 6 used common copper wire (AC 220 V) to conduct overcurrent experiments, and the results showed that overcurrent faults can be divided into three stages of smoke, redness, and breakdown; Babrauskas 7,8 reviewed the fire process of PVC wire insulation caused by typical electrical faults, and he also discussed the prior studies on ignition of electrical wiring due to overcurrent conditions; Orcajo et al 9 found that the overcurrent fault is generally the primary cause of fire by studying the mechanism of overcurrent faults; Wen et al 10 studied the functional relationship between the flame shape characteristics of the low-voltage overloaded wire and the flame spread speed, current, and inclination angle and derived the theoretical analysis method of the flame spread mechanism of the overloaded wire; Kobayashi et al 11 studied the influence of different core wires and insulated wires on the flame spreading process, and concluded that the influence of insulation type on flame spreading is limited; Meinier et al 12 studied the effect of an external heat source and cable distance on the fire characteristics of cables, and identified the significant role of insulating materials in combustion; Wang et al 13 studied the effect of wire aging thermal stability and aging degree on flame spread; Fisher. 14 studied the no-load, bending deformation, energization, and pyrolysis breakdown time of the wire under the condition of radiant heat using the PVC pyrolysis model and defined the fault occurrence process of the wire; Wang et al 15,16 studied the thermal degradation kinetics of new and old PVC sheaths and found that the aging sheaths usually undergo pyrolysis, mainly because the peak weight loss rate is higher at a higher initial decomposition temperature; An et al 17 studied the flammability and flame spread characteristics of PVC cables, and the results provided a foundation for fire risk assessment and safety design of PVC cables; Sun et al 18 simulated the short-circuit process of wires under different overcurrents, and revealed that in the identification of fire evidence, the type of short-circuit cannot be judged only by the metallographic structure characteristics; Cai et al 19 simulated overcurrent faults in copper wires at four to seven times the rated current and studied the differences in metallographic structure and microstructure characteristics under different currents; Bo et al 20 studied the heating, fusing, and burning phenomena of a flame-retardant single-core PVC-insulated copper conductor with different overcurrent values and the metallogr...…”

Experimental Study on Combustion Behavior of U-Shaped Cables with Different Bending Forms and Angles

“…Huang et al [7] studied the influencing factors of the flame spread behavior of the cable and the study found that the flame spread rate increases with the increase of oxygen concentration. An et al [8] conducted a fire experiment on PVC cables, demonstrating that, with the increase in the number of cables, both the length of the thermal decomposition combustion zone and the speed of flame propagation escalate. Zhao et al [9] carried out an experimental study on the impact of the current on the spread of fire in polyethylene cables and the study found that flames spreading downwards are more susceptible to the influence of the current.…”

Study on Combustion Characteristics of Cable Based on Cone Calorimeter

“…Some scholars used a cone calorimeter to study the combustion characteristics of PVC cables and obtain fire characteristics such as ignition time, heat release rate, mass loss rate, smoke generation rate and so on. It was found that the structure of PVC cables affected the ignition time [12][13][14]. At present, no article has studied the heat conduction process of XLPE cables.…”