# Identification of the Wear Margin of a Pipeline-Machine Subsystem
## 6 Results and Discussion
To fill the vessel from pressure \(p_{1}\) (1.0 bar) to pressure \(p_{2}\) (6.5 bar), the subsystem absorbed energy \(E_{el}\) was 0.231 kWh and the time of filling was 85 s. The subsystem efficiency, for such pressures calculated by Formula (50), was  
\[\eta_{ez}\ =\ \frac{V_{z}\cdot(p_{2}-p_{1})}{E_{el}};\eta\ =\ 0.264 \tag{64}\]  
In the second case, the filling capacity of a hydrophore \(\dot{V}_{zh}\) (Equation (54)), the efficiency of filling the hydrophore \(\eta_{ezh}\) (Equation (61)) and efficiency of subsystem filling \(\eta_{ezh}\) (Equation (63)) were calculated by Equations (54), (61) and (63) for the filling of a subsystem consisting of an open vessel-pipeline-pump-pipeline-hydrophore vessel. That subsystem had a single-acting positive displacement plunger pump. According to the maker, the pump capacity is 1.40 (m\({}^{3}\)/h)/0.39 (L/s), the discharge head is 60 m H\({}_{2}\)O/6.0 bar (1 m H\({}_{2}\)O = 0.098 bar) and the motor power is 0.45 kW. The hydrophore vessel had a total volume of 70 L (0.070 m\({}^{3}\)). The measurements included air pressure \(p_{1}\) and \(p_{2}\), filling time \(\Delta t\) and electric energy \(E_{el}\) of the electric power used by the motor during water volume change in the vessel by \(\Delta V\) = 30 L (\(V_{1}\) = 0.015 m\({}^{3}\), \(V_{2}\) = 0.045 m\({}^{3}\)). Volumes were measured by a water level gauge integrated with the hydrophore. Time was measured with a stopwatch, and the pressure was measured with a manometer. No impact of pressure in the examined interval on filling time was found. The measured time of filling was 78 s. The calculated filling capacity of a hydrophore (vessel filling capacity) \(\dot{V}_{zh}\) was 0.38 L/s. The other results of measurements and calculations are given in Table 1. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**\#** & \(\mathbf{p_{1}(bar)}\) & \(\mathbf{p_{2}(bar)}\) & \(\frac{p_{2}}{P_{1}}\) & \(\mathbf{n}\) & \(\mathbf{L_{1-2}}\)Polytropic (Nm) & \(\mathbf{p_{c}(bar)}\) & \(\mathbf{E_{el}(Wh)}\) & \(\mathbf{\eta_{ezh}}\) & \(\mathbf{\eta_{ezh}}\) \\ \hline
1 & 1.0 & 3.15 & 3.15 & 1.452 & \(-\)5254.4 & 1.751 & 7.0 & 0.208 & 0.327 \\
2 & 1.5 & 4.7 & 3.13 & 1.447 & \(-\)7829.9 & 2.609 & 8.0 & 0.271 & 0.428 \\
3 & 2.0 & 6.1 & 3.05 & 1.414 & \(-\)10,265.7 & 3.422 & 9.0 & 0.317 & 0.502 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of the test results for a displacement pump subsystem and a hydrophore vessel. It follows from theoretical and experimental tests that, within the specific boundaries of a pipeline-machine subsystem with a machine driven by an electric motor, the methods and resources for identification tasks depend on the way the subsystem works. In the case of an open subsystem, particularly in steady-state conditions, it is desired and possible to determine the initial, suction, discharge and final fluid pressures; the initial, suction, discharge and final fluid temperature; the volume flow rates at the beginning and at the end of a subsystem; and the electric energy or input power of the electric motor. The measured values of these quantities allow us to calculate values of the efficiency of the whole subsystem, the hydrodynamic efficiency of the suction and discharge pipes, the hydrodynamic efficiency of the machine (pump) and the efficiency of the motor-machine set. Desired value ranges can be defined for the hydrodynamic efficiency of the suction and discharge pipes and the efficiency of the whole set. If a real value of suction/discharge pipe hydrodynamic efficiency is found to be outside the desired range, we should start looking for the cause, using the relationships between efficiency, pressure drop and coefficients of hydraulic resistance. The characteristics of the wear margin affecting the value of a given hydraulic resistance coefficient make up a list of probable causes.