## 6 Systems Encapsulation and Installation
For the battery cells, it is suggested they be placed at the bottom of the tube. This helps the centroid of the tube to be underground. Moreover, the rich set of pipe management accessories, e.g., expansion adaptors, fittings, tees, sleeves, connectors, bends, flanges, etc. can be creatively used for sensory installation above the surface or underground. Figure 29a displays a SensoTube-based WSAN node in an orchard. As it is shown, the plastic tube has been used not only for the encapsulation of the electronic systems but also as a support pole. The solar panel of the node has been easily adapted to the top cap of the plastic tube, as it is shown in Figure 29b. In contrast with the traditional installation methods, such as that of Figure 27, in the proposed installation method the RF antenna is encapsulated within the tube and in this way they are fully protected from the external environment. \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{2}{c}{**Pressure Tolerance**} \\ \cline{2-3}  & **4 atms** & **6 atms** \\ \hline Material & & PVC-U \\ Outer Diameter & & 90 mm \\ Thickness & 1.8 mm up to 2.2 mm & 2.7 mm up to 3.2 mm \\ Mass & 0.785 kg/m & 1.15 kg/m \\ Standards & EN1452-2 [157], DIN 8061, DIN 8062 \\ Cost & & 4 USD/m \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Specifications of a 90 mm diameter PVC tube that can be used as the encapsulation and support pole of WSAN node according to the SensoTube architecture. Figure 28: A typical example of the encapsulation of a WSAN functional shield based on the SensoTube architecture. The electronic components of the node are designed in the form of expansion shields able to be inserted within plain irrigation PVC tubes of 90 mm diameter. (**a**) A three-dimensional view showing a SensoTube shield inside a tube; (**b**) a real implementation of the proposed encapsulation method. The advantages of the SensoTube approach for the WSAN hardware enclosures are numerous. Some of them are listed below:  
* _Ruggedness:_ The drain and water PVC tubes by default assure the coveted resistance to water, chemicals, salinity, acids, etc. * _Non-metallic support poles:_ the use of the plastic tube as the support pole benefits the total system because the weight is greatly reduced. Furthermore; the material is inexpensive compared to traditional metallic constructions. In addition, it provides better lightning protection. Finally, it is not attractive to thieves looking for scrap metal. * _Underground installation:_ It is a robust enclosure solution for WSAN nodes in underground installation where the whole of the node, or the most of it, has to be buried underground [158]. * _Internal temperature stability:_ The temperature of the air mass inside a PVC tube is slightly different from that of the open air, because this plastic material has a very low thermal conductivity. Also, as deeper the tube is installed underground, the temperature difference is increased due to the facts that a certain part of the enclosure are not directly exposed to the external environment, and that the temperature under the surface is almost constant during the day and night periods. Thus for deployments in environments with high temperature and high sunlight radiation it is possible to keep the temperature of the enclosed electronics at a lower level with regard to the open air temperature. Such a feature is of great importance for the energy balance of the WSAN system. * _Easy deployment:_ PVC tubes are easily transported and, due to their convenient centroid, they do not require deep paddles and cableways for their support on the ground. * _Larger inner space:_ e.g., in a 2.5 m PCV tube of 90 mm diameter and 2.7 mm thickness, the total inner useful volume is about 13,723 cm\({}^{3}\) whereas the inner volume of a 170 mm \(\times\) 170 mm \(\times\) 75 mm electrical enclosure, such as the one displayed in Figure 26a, is just about 2100 cm\({}^{3}\).