# Result Charts - Pipes

For pipe results there are 10 different types of chart available. The availability of each chart depends on the fluid phase state. For all phase states a resistance chart is available. This shows the pipe friction loss at various flows. Figures 1 to 3 show examples for different fluids. Figure 1: Pipe friction loss for a Newtonian fluid Figure 2: Pipe friction loss for a settling slurry Figure 3: Pipe friction loss for a Non Newtonian fluid For gas flows the velocity, static pressure, static temperature and static density can vary significantly as the vapor flows down the pipe. Figs 4 to 7 show these properties as a function of pipe length. Figure 4: Gas static density with position Figure 5: Gas static pressure with position Figure 6: Pipe velocity increase Figure 7: Gas static temperature decrease with position For two phase flow the flow pattern map and the variation of quality with pipe length can also be considered. Figure 8: Flow Pattern Map (Friedel) Figure 9: Vapor mass fraction increasing with pipe length Hydraulic and Energy Grade Line Charts FluidFlow allows users to graphically represent the level of energy in a piping system by means of the Energy (EGL) and Hydraulic (HGL) Grade Lines. These imaginary lines allow the engineer to quickly identify any "trouble-spots" in the system (typically points of low pressure). This graph plot can be developed by selecting the "Tools | Composite Chart Setup..." menu item, then define the start and end boundary nodes for your EGL & HGL plot. Figure 10 provides details of the required information. Note, you can also change the length and head units for the graph plot. Figure 10: Hydraulic and Energy Grade Line Setup. Once you have completed the data entry noted in Figure 10, select "Make Plot" and FluidFlow will then develop a graph plot which should appear as set out in Figure 11. Figure 11: Sample Energy and Hydraulic Grade Line Chart. The Energy Grade Line (EGL) The Energy Line is a line that represents the total head available to a fluid. For a fluid flowing without any losses due to friction (major losses) or components (minor losses) - the energy line would be at a constant level. In practice, the energy line decreases along the flow due to various energy losses. The EGL is formed by the locus of points a distance v2/2g above the HGL, or a distance v2/2g + P/ρg + z above a pre-selected datum. The Hydraulic Grade Line (HGL) The Hydraulic Grade Line is a line representing the total head available to the fluid - minus the velocity head. If a pipe is under pressure, the hydraulic grade line is that level water would rise to in a small, vertical tube connected to the pipe. The following tips are useful when plotting the HGL & EGL graph: 1. As the velocity reaches zero, the HGL and EGL merge. 2. Both the HGL and EGL slope downwards in the direction of flow due to head loss in the system. 3. An abrupt change occurs in the HGL and EGL whenever a loss occurs due to a sudden geometry change, i.e., a valve or a reducer/expander. 4. A "pitch" occurs in a HGL and EGL whenever energy is added to a fluid, e.g. a pump. A dip will occur when energy is extracted from the system, e.g. a turbine. 5. When the HGL passes through the centerline of a pipe, the pressure is zero. If the pipe lies above the HGL, there is vacuum in the pipe The HGL is formed by the locus of points a distance P/ρg above the center of a pipe or P/ρg + z above a pre-selected datum.