AFT Blog
In AFT Impulse you can directly model a submerged pump. First, you will define your pump data exactly as you would normally, however you will only draw the discharge piping and not a suction piping. After doing this, you will check the box “Submerged Pump” at the bottom of the Pump Specifications Window. You now have an additional required input field. The “Suction Pressure” can be entered as a Head (HGL) or a Pressure. When entered as a Head (HGL) value, this value is the actual liquid elevation in the supply reservoir. When entered as a pressure, this is the actual...
The ability to specify default input parameters is a feature that is common to all AFT software products. Diameter, Friction Model, and Design Factors can be specified by default for pipes. Input properties for Junctions are specific to each junction type, so the only common default property is elevation. The default input options are found in “Parameter and Unit Preferences”. In general, this feature makes model building faster and more efficient. The user should, however, be aware of how this affects the “Status” of pipes and junctions. The “Status”, to which I am referring, is the green light to run the...
AFT Fathom 8 can be used to quickly and easily model multiple pump configurations with different pump speeds and impeller sizes. First, determine a particular pump curve to use from either a manufacturer’s pump curve or pump curve verification test data. Next, determine new pump curves for head and flow using the affinity laws considering either a change in pump speed or impeller size. The multiple pump curve data sets will then be entered for each particular pump configuration. In Figure 1 (click on the image to see it larger), there are a few pump configurations that have already been defined. ...
AFT Fathom has the ability to model heat transfer. The default mode (found in system properties) is “Constant Fluid Properties”. To avoid confusion in the default mode, several of the heat transfer input fields and option boxes are invisible or disabled until one of the following heat transfer modes are employed: Heat Transfer With Energy Balance (Single Fluid)Heat Transfer With Energy Balance (Multiple Fluids) Upon selecting one of these heat transfer modes, the user may notice an option box labeled “Balance Energy at Junction”; found at the lower left of the first tab in the properties window for the Assigned Pressure...
AFT Fathom provides a Three Way Valve which increases the Engineer’s capability to model system control. The Three Way Valve Properties Window shows the three connecting pipes in drop-down lists, which allows users to specify which pipe is the combined flow pipe, and which two are the split flow pipes. By entering the loss profile through each flow path, and then by selecting the actual percent open, Fathom will calculate the actual loss values for each flow path. Using the Three Way Valve in conjunction with the Goal Seek & Control module (GSC) increases the Engineer’s capability to model I&C logic...
Relief valves can be modeled in four different configurations with AFT products and they are shown in the figure below. The required inputs for modeling a relief valve are the valve type, cracking pressure, valve loss model, and the exit pressure in the case of relieving to the atmosphere. There are three types of relief models available: Internal (Cases 1 & 1a), Relief Valve at Exit (Case 2), and Inline Exit (Case 3). In cases 1 and 1a, the relief valve is relieving into vent piping downstream of the valve. Note that there is initially no flow in the pipe downstream...
One of the many new features in Fathom 8 is the ability to show images in the annotation box. This simple feature will allow the engineer to easily and clearly communicate a vast array of information through the Workspace and Visual Report. To add an image to the Workspace or Visual Report, as seen above, select the Annotation tool from the toolbox. Then select the “Line/Arrow/Image” tab and specify the file path to your image. Once the image is selected, click OK. The image box shown on the workspace can be easily moved and resized.