One of the main challenges for the EU DEMO reactor is to achieve tritium self-sufficiency by means of the Tritium Extraction and Removal System (TERS). The Permeator Against Vacuum (PAV) is a candidate to become the tritium extractor for the TERS: it has a shell-and-tube configuration, where tritium is dissolved in the carrier liquid metal (PbLi) and is forced to cross a metallic (niobium) membrane by pumping vacuum on the secondary side. However, currently there are huge uncertainties in the tritium transport properties, particularly regarding solubility values, which pose a significant challenges for the modeling of tritium permeation. This work aims at comprehensively understand tritium transport within the PAV.