# Instrumental Uncertainty of Conductance Transducers for
## 6 Discussion  
The performed study showed that the proposed metrological characterization methods are suitable for the determination of the instrumental measurement uncertainty of conductance transducers used in maritime reduced-scale models, and can be used as a \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Uncertainty** & **Source of** & **Probability** & **Standard** & **Sensitivity** & **Contribution** & **Degrees of** \\
**Component** & **Uncertainty** & **Distribution** & **Uncertainty** & **Coefficient** & **for Uncertainty** & **Freedom** \\ \hline \(u(t)_{\text{lin}}\) & Linearity & Uniform & 2 mm/\(\sqrt{3}\) & 1 & 1.2 mm & 50 \\ \(u(h)_{\text{rev}}\) & Reversibility & Uniform & 0.5 mm/\(\sqrt{3}\) & 1 & 0.29 mm & 50 \\ \(u(h)_{\text{rep}}\) & Repeatability & Gaussian & 0.10 mm & 1 & 0.10 mm & 5 \\ \(u(h)_{\text{stb}}\) & Stability & Gaussian & 0.007 mm & 1 & 0.007 mm & 29 \\ \(u(t)_{\theta,t}\) & Temperature & Uniform & 2 mm/\(\sqrt{3}\) & 1 & 1.2 mm & 50 \\ \(u(h)_{\theta,r}\) & Thermal & Uniform & 0.5 mm/\(\sqrt{3}\) & 1 & 0.29 mm & 50 \\ \(u(h)_{\text{cur}}\) & Calibration & Gaussian & 0.72 mm & 1 & 0.72 mm & 43 \\  & curve & & & & & \\  & Slope & Gaussian & 0.13 mm\(\cdot\)V\({}^{-1}\) & 5 V & 0.65 mm & \\ \(u(m)\) & parameter & Gaussian & 0.78 mm & 1 & 0.78 mm & \\ \(u(b)\) & Parameter & Gaussian & 0.0013 V & \(-\)29.74 & \\ \(u(V)\) & Output voltage & Gaussian & 0.0019 V & mm\(\cdot\)V\({}^{-1}\) & 0.039 mm & 30 \\ \(u(V)_{\text{cal}}\) & Multimeter & Gaussian & 0.00019 V & 1 & 0.00019 V & 50 \\ \(u(V)_{\text{drf}}\) & Drift & Uniform & 0.000024 V/\(\sqrt{3}\) & 1 & 0.000014 V & 50 \\ \(u(V)_{\text{res}}\) & Resolution & Uniform & 0.000005 V/\(\sqrt{3}\) & 1 & 0.000003 V & 50 \\ \(u(V)_{\text{stb}}\) & Signal stability & Gaussian & 0.0013 V & 1 & 0.0013 V & 29 \\ \hline \end{tabular}
\end{table} 
Table 6: Measurement uncertainty budget for the \(\pm\) 140 mm conductance transducer. regular laboratorial calibration method, making water level measurements traceable to the SI. In this context, improvements are still possible, namely, the conductance transducer testing only in a wet condition, which should improve the repeatability and the reversibility of the conductance transducers measurements. Special care should also be given to measurements performed in extreme regions of the measurement interval. The developed instrumental measurement uncertainty evaluation procedure is now available for application in the wide range of LNEC's conductance transducers. The obtained values can be accounted for in field and computational simulations, therefore, improving the study of the physical phenomena. Future work will be focused in the metrological study of in situ application of LNEC's conductance transducers in maritime reduced-scale models, since this study revealed a significant impact of the electrical and environmental influence in the measurement accuracy. Validation of in situ on-the-job verification procedures is a key issue, which will be considered in the near future, namely, the development of measurement standards and methods able to provide in situ traceability transfer. [PERSON] and [PERSON] conceived and designed the performed investigation; the testing methodology was defined by [PERSON], [PERSON], and [PERSON]; [PERSON] was responsible for the development and validation of software related to data acquisition and analysis; [PERSON] and [PERSON] performed the experiments; [PERSON] validated the obtained results; [PERSON] wrote the paper, which was reviewed by [PERSON], [PERSON], [PERSON], and [PERSON] All authors have read and agreed to the published version of the manuscript. This research was funded by LNEC--National Laboratory for Civil Engineering, integrated in the Portuguese Ministry of Infrastructures and Housing. Not applicable.