## 5 Conclusions  
Four series of three polymeric and one inorganic flat membranes were analyzed using a precise, accurate, and fast automated CFP/LEP commercial device. The device designed and marketed by IFTS is an accurate CFP porometer that has been improved by connecting it to an analytical balance and proper LEP cell. The setup was able to analyze filters ranging from UF to particle filtration membranes. Both techniques (CFP and LEP) were developed to provide information about the PSD of membranes and filter media, and make use of the same Young-Laplace equation to convert experimental data into pore size values. The techniques differ in the role of wetting/pushing fluids in the process of emptying membrane pores from a previous filling fluid.  
For two UF membranes, only CFP (by using two liquid phases, then LLDP) was used to obtain PSD information, while for bigger pores, the filter (MF and particle filtration) results from CFP and LEP were obtained and compared.  
The results are very interesting, and showed a nice agreement between different runs for both techniques (slightly better in the case of CFP) and reasonable agreement was also found when comparing the CFP and LEP outputs, except that the FM filter, which is hardly considered as a bundle of parallel pores as their fibrous structure is closer to a system of highly interconnected pores. This led to a broader PSD coming from LEP than that from the procedure based on the flow-rate curve (which in turn, was not able to discriminate bigger pores not contributing to flow). As a result, the information on the PSD, and mainly, the mean pore sizes obtained from it, can be questioned and must be assessed.  
In conclusion, we can assert that an accurate LEP technique measuring air-liquid capillary pressure curves of porous and non-porous structure materials has been developed, where the results are coherent with porous membranes, especially when these membranes are well resembled by a capillary pore model.  
**Author Contributions:** R.I.P. made the measurements and R.B.A. and J.I.C. collaborated in the interpretation of results and paper writing. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the French \"Ministere de l'Enseignement superieur, de la Recherche et de l'Innovation\" through by (Credit Impot de la Recherche CIR-IFTS-2020).  
**Conflicts of Interest:** The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Membrane** & \begin{tabular}{c} **Nominal \(d_{avg}\)** \\ **(\(\upmu\)m)** \\ \end{tabular} & \begin{tabular}{c} **Young-Laplace** \\ **Technique** \\ \end{tabular} & \begin{tabular}{c} \(d_{avg}\) (\(\upmu\)m) Flow-Based or** \\ **Mass Based** \\ \end{tabular} & **Wetting Liquid** \\ \hline \(\text{Al}_{2}\text{O}_{3}\) & 0.02 & LLDP & 0.0226 \(\pm\) 2.6\% & Alcoholic Phase \\ \hline PET & Not available & LLDP & 0.0274 \(\pm\) 2.1\% & Alcoholic Phase \\ \hline NC & 5 & \begin{tabular}{c} GLDP \\ LEP \\ \end{tabular} & \begin{tabular}{c} 3.1 \(\pm\) \(<\)1\% \\ 5.2 \(\pm\) 5.7\% \\ \end{tabular} & \begin{tabular}{c} FC-43 \\ Water Rich Phase \\ \end{tabular} \\ \hline FM & Not available & \begin{tabular}{c} GLDP \\ LEP \\ \end{tabular} & \
\begin{tabular}{c} 16.8 \(\pm\) 7.1\% \\ 33.5 \(\pm\) 7.0\% \\ \end{tabular} &
\begin{tabular}{c} Ultra-Pure Water \\ Ultra-Pure Water \\ Ultra-Pure Water \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}
Table 2: Mean pore diameters (\(d_{avg}\)) obtained via FCP and LEP for the four membranes tested.