Conduit system for fluids in a fuel cell

An element of a conduit system for a fuel cell comprises an inner layer of polyester moulding material (in contact with the transported medium) and at least one of the following: (a) a layer of polyamide; (b) a layer of functionalised polyolefin; (c) a layer of non-functionalised polyolefin; and (d) a layer of EVOH. An independent claim is also included for a fuel cell system containing this element, especially for use in motor vehicle power units.