NF X70-100: Toxicity tests for railway materials

Toxicity testing according to NF X70-100-1 and -2 standards is performed to determine the Conventional Index of Toxicity for non-listed products (CIT_NLP) used on trains.

Testing is needed to meet requirements R22 and R23, as specified in standard EN 45545-2 on the fire behavior of materials used in railway vehicles. These requirements apply to products such as window seals, door joints, isolators, coils, pipes, and hoses.

During the analysis, the sample is burned in a tube furnace at 600 °C, and toxic smoke emissions evolving from the sample are collected and analyzed. The concentrations of the following eight gasses are measured and used to calculate the CIT_NLP parameter:

• Carbon dioxide (CO₂)

• Carbon monoxide (CO)

• Hydrogen fluoride (HF)

• Hydrogen chloride (HCl)

• Hydrogen bromide (HBr)

• Hydrogen cyanide (HCN)

• Sulfur dioxide (SO₂)

• Nitrous oxide (NO_x), including both NO₂ and NO, expressed as NO₂