A device for conveying a substance that comprises: a first duct for containing the substance; an optical fiber connected to the first duct and extending along the duct, the optical fiber including several detection members spaced along its length, each detection member having a separate reflection spectrum that varies with the presence of the substance to be detected; a control device including a light source capable of emitting a light in the reflection spectrum of each detection member, a light receiver capable of detecting the light amplitude in the detection spectrum of each detection member, and an analysis module capable of determining the presence of a leak of the substance based on the light amplitude provided by the light receiver.