fluid conduit segments are provided that include , but are not limited to integrated heating systems for protection against freezing . to this effect ptc - fabric heating elements are provided that are integrated in the fluid conduit segments and that in the negative temperature range include , but are not limited to a ptc - temperature - dependent resistance . the heating system thus provides a higher output in the negative temperature range and a lower output in the positive temperature range , i . e ., the heating limits itself until temperature equalization has been reached .