When designing railway vehicles, the safety and protection of passengers and on-board staff is essential, in particular in case of a fire.

LAPI, the accredited test laboratory based in Prato, Italy, has tested the combination of Peters’ conformal coating ELPEGUARD® SL 1307 FLZ/2 and ELPEPCB® solder resist Elpemer® SD 2467 SM-DG on both the base material Panasonic R-1755 and the prepreg Panasonic R-1650, in accordance with the EN 45545-2 standard ”Railway applications – Fire protection on railway vehicles: Requirements for fire behaviour of materials and components“, requirement sets R24 and R25.

The R24 requirement set implies to determine the limiting oxygen index (LOI) in accordance with EN ISO 4589-2, in view of evaluating the relative flammability of materials. With a result of 55.7 %, the oxygen index of the above combination of materials distinctly exceeds the minimum threshold of 32 % needed to achieve the highest hazard level 3, and is thus particularly flame-retardant.

The R25 requirement set specifies the testing of flammability by means of a glow wire according to EN 60695-2-11, where under extreme operating conditions simulated, individual components heat up strongly or start to glow, such as overloaded resistors or coils. The specimens coated with ELPEGUARD® conformal coating and Elpemer® solder resist did not ignite at a glow wire temperature of 850 °C and thus here, too, reached hazard level 3 of EN 45545-2 which describes the strongest requirements for the materials tested.

This way, using the conformal coating ELPEGUARD® SL 1307 FLZ/2 paired with ELPEPCB® solder resist Elpemer® SD 2467 SM-DG may contribute very effectively, when applied on the appropriate base materials, to reaching a high level of safety on trains.