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All tips refer to the current version of the applicable software
product. Tip applicability is shown by the products listed below
the tip title.
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Fathom Tips
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Building Multiple Models
Fathom, Arrow, Mercury, Impulse
While we usually think of building a system model in the Workspace (and, of course, we can have multiple models within a file in different scenarios), you can have multiple, disconnected system models within the work space simultaneously. This has many uses, including facilitating parametric modeling. For example, you're modeling a system with a defined supply flow and want to evaluate the results for various supply flow rates. After building the model, select the whole model (Edit/Select All or ctl+a), then duplicate it (Edit/Duplicate or ctl+d) as many times as desired. For each instance specify a different supply flow and, after running the model, can now compare results for the different supply flows within the same Output window.
Eliminating 'negative' flows
Fathom, Mercury, Impulse
Flow direction arrows are for reference only, the actual direction being determined by the analysis and, if the direction is opposite the reference direction you've specified, values for flow, velocity and pressure drop will be negative. If you don't want negative values, simply select the pipe, press F3 to toggle the direction arrow and rerun your model. While this is fine for one or a few pipes, what if you have many pipes with negative flow values? Within the Workspace, open Select Special (on the Edit menu or by pressing F6). For 'Selection Type', select 'Pipe Output Properties', then 'Volumetric Flow Rate' for the 'Pipe Property'. Next to 'Range', input a negative flow value in the 'From' field larger than the largest negative flow in your output and '0' in the 'To' field, then click on 'Select Pipes'. Click on 'OK' and you'll be back in the Workspace with all of the pipes with negative flows selected. Now, simply press F3 to reverse the flow direction arrows of all the pipes and rerun your model. No 'negative' flows. P.S. You can also Select Special pipes based on negative velocity.
Moving a junction without moving the pipe
Fathom, Arrow, Mercury, Impulse
Click on the junction to be moved once to select it. Then hold the Ctrl key down while you drag the junction icon and the pipes will remain in their current location. Note this results in the pipes being disconnected from the junction.
Merging two models together
Fathom, Arrow, Mercury, Impulse
Models may be merged together by selecting Merge... from the File menu. Before starting this process it is always advisable to save your current model. You will be asked for the file name to merge into the current Workspace. The model being merged in will be placed on the Workspace and each object will be selected. Move the merged model by positioning the mouse pointer on a selected junction and holding down the left mouse button and dragging it to the desired location on the Workspace. If you accidentally click somewhere off the selected items they will be come unselected and it may be more difficult to move the merged model into position. If this happens, simply reload the original model and start the merging process over again.
Building large models - The building block approach
Fathom, Arrow, Mercury, Impulse
Very large and complex models may be constructed by building smaller models and merging them together. It is a good idea to break the large system into logical parts where there known boundary conditions (flowrates or pressures).
Quick inspection of pipe and junction properties
Fathom, Arrow, Mercury, Impulse
The inspection feature saves time by displaying the properties of a Workspace object in a read-only fashion. To inspect an object, position the mouse pointer on the object and hold down the right mouse button.
Quick inspection of the connected pipes or junctions while in a specification window
Fathom, Arrow, Mercury, Impulse
To check the properties of the objects connected to the one you are specifying, position the mouse pointer on the connected object's ID (listed in the specification window) and hold down the right mouse button.
Highlight the required data fields for pipes or junctions
Fathom, Arrow, Mercury, Impulse
The areas on the Specification Window which are required can be highlighted by either pressing the F2 key or by double-clicking on a blank area somewhere on the Specification Window.
Jumping to the pipe or junction which is not completely defined
Fathom, Arrow, Mercury, Impulse
To show the undefined pipes or junctions click the magnifying glass toolbar icon or selecting Find.. from the View menu. Then choose the option to Show Undefined. The lists now contain only those pipes or junctions which are not completely defined. Select the item from the list and click on the Find button.
Jumping from Pipe to Pipe or Junction to Junction
Fathom, Arrow, Mercury, Impulse
You can jump from junction to junction or from pipe to pipe by pressing F5 while in a specifications window.
Keyboard Shortcuts
Fathom, Mercury
Selection Drawing Tool
Double-clicking tool - Tool remains active
Control key - Tool remains active above +
Shift key - Deselects pipes and junctions
Alt key - Toggles pipe and junction selection
Pipe Drawing Tool
Double-clicking tool - Tool remains active
Control key - Tool remains active
Shift key - Draws horizontal or vertical pipes
Zoom Select Tool
Shift key - Zoom state will always be 100%.
Dragging junctions from Toolbox
Control key - Morphs junction
Shift key - Splits pipe
Inspecting pipes and junctions
Right click +
Shift key - Shows undefined items
Control key - Shows Output data
Alt key - Shows optimized data (AFT Mercury only)
Control and Alt key - Shows Output and (AFT Mercury only) Optimized data
Moving junctions with connected pipes
Control key - Move junctions but not pipes (no snap)
Pipe and junction specifications window
F2 - Highlight feature toggle
F5 - Jump to next higher pipe or junction
Ctrl+F5 - Jump to next lower pipe or junction
Selection Drawing Tool
Double-clicking tool - Tool remains active
Control key - Tool remains active
Above +
Shift key - Deselects pipes and junctions
Alt key - Toggles pipe and junction selection
Pipe Drawing Tool
Double-clicking tool - Tool remains active
Control key - Tool remains active
Shift key - Draws horizontal or vertical pipes
Zoom Select Tool
Shift key - Zoom state will always be 100%.
Dragging junctions from Toolbox
Control key - Morphs junction
Shift key - Splits pipe
Inspecting pipes and junctions
Right click +
Shift key - Shows undefined items
Control key - Shows Output data
Alt key - Shows optimized data (AFT Mercury only)
Control and Alt key - Shows Output and (AFT Mercury only) Optimized data
Moving junctions with connected pipes
Control key - Move junctions but not pipes (no snap)
Pipe and junction specifications window
F2 - Highlight feature toggle
F5 - Jump to next higher pipe or junction
Ctrl+F5 - Jump to next lower pipe or junction
Edit
Ctl+Z - Undo
Ctl+C - Copy
Ctl+X - Cut
Ctl+V - Paste
Ctl+D - Duplicate
Ctl+A - Select all
F6 - Select special
View
Ctl+H - Show object status
Ctl+F - Find
Ctl+K - Open Calculator (within Specification window)
Analysis
Ctl+R - Run model
Arrange
Ctl+E - Pipe segments
Ctl+L - Lock object
F3 - Reverse (flow) direction
Modeling a valve opening
Fathom XTS Module
To model a valve opening transient from the closed position, apply the Special Condition / Closed on the specifications window Optional tab. Transient Data then starts with Cv = 0, increasing to the full open Cv value, or, if modeling the valve loss as a K value, transient data starts with K = -1 (K = infinity), decreasing to a K value for the open position (all K values other than the full closed K value are positive).
Pipe elevations at a reservoir
Fathom XTS Module
Specifying a pipe connected to a reservoir using a pipe depth will keep the pipe at a constant elevation relative to a changing liquid elevation. For a constant absolute pipe elevation, specify the connected pipe using pipe elevation.
Generating a pump/system curve for a selected time step
Fathom XTS Module
System and Pump vs System curves always reflect the conditions at the first time step. To graph curves at a different time step, run the simulation to the time step of interest, then create a disconnected scenario from the View menu. Load this new scenario and use it to generate the system / pump vs system curve.
Limiting variables to a desired range
Fathom GSC Module
Specify upper and/or lower bounds to force a GSC solution within desired limits, such as a pump speed not exceeding 100%.
Creating a model with GSC solution variable values
Fathom GSC Module
To create a version of your model with input values equal to the solved GSC variables, with the Output window open, make a disconnected scenario from the View menu.
Changing input values to obtain a GSC solution
Fathom GSC Module
If GSC is unable to find a solution, try changing the specified input value of the variable(s) to provide the solver a different starting point.
Hiding/Showing items with zero costs in the Cost Report
Fathom CST Module
You can specify if pipes, junctions or fittings that do not have any cost calculated should be included in the Cost Report in the Output Control. Open Output Control from the Analysis menu and click on the Format & Action tab. In the Cost Report Formatting area, check or clear the Don’t Show Object With Zero Costs option.
Changing the order of magnitude displayed in the Cost Report
Fathom CST Module
If you are displaying very large numbers in the Cost Report, you can change the order of magnitude scale that is displayed to reduce the number of digits shown. For example, you can specify that the table show millions of US Dollars (or what ever monetary unit you are using) and all the cost values will be divided by 10^6. This setting is shown in the upper left corner of the table, just below the monetary units used. To set the magnitude, open the Output Control from the Analysis menu and click on the Format & Action tab. In the Cost Report Formatting area, choose the appropriate Unit Style from the drop-down list. You can also specify the number of decimal places used for both the items and the subtotals.
Possible causes for not getting costs in the Cost Report
Fathom CST Module
There are several reasons why costs are not being calculated or shown in the Cost Report. If you are having trouble, please go through this checklist which may help pinpoint the problem.
1) Is “Calculate Costs” set in the Cost Settings from the Analysis menu?
2) Is a cost type (e.g. Material, etc.) selected in the Cost Definition area of the Cost Settings?
3) Is a cost database connected through the Database Manager and is the correct database section selected?
4) Does the cost database have the correct information for the object? You can verify the contents of a cost database by opening it in the Cost Database editor and clicking on the Summary tab.
5) Does the object have “Include in Cost” set on the Cost tab in the Specifications Window?
6) Does the object have either “All connected cost database” or the correct specific cost database selected in the Cost Information area on the Cost tab in the Specifications Window?
7) Are the Cost Multipliers non-zero in the Cost Information area on the Cost tab in the Specifications Window?
8) If the object is a junction, is it set to a junction from Database? This is set near the top of the Specifications Window in the Database List drop-down. If it is empty, it is not connected to a database item, from which a cost is calculated.
9) Are the correct items selected to be shown in the Cost Report? These are set in the Output Control, Summaries tab. Choose Cost Report from the list and verify that the appropriate parameters (e.g. Material, etc.) are checked.
10) For recurring costs, does the Service Time of the object match the System Life?
11) Are zero-cost items being hidden? This is set on the Format & Action tab of the Output Control.
Limit Pipe & Junction Label Movement
Fathom, Fathom CST Module, Fathom GSC Module, Fathom XTS Module, Arrow, Mercury, Impulse, Titan
You can specify that pipe or junction labels can only be moved on the Workspace when the Shift key is pressed. Sometimes the labels get in the way of selecting the pipes of junctions themselves and are moved accidentally. You can change this to use the Shift key in the Allowable Workspace label movements are in Workspace Presference (on the Options menu).
Selecting English or SI Units
Fathom, Fathom CST Module, Fathom GSC Module, Fathom XTS Module, Arrow, Mercury, Impulse, Titan, SteamCalc, ChemPak
To choose only English or SI units for all parameters, select Parameter and Unit Preferences from the Options menu, then select the Unit Prefrences tab, choose the Default Unit System and click the Apply Default Units button. This will use will the default units and change the preferred units.
Morphing Junctions
Fathom, Fathom CST Module, Fathom GSC Module, Fathom XTS Module, Arrow, Mercury, Impulse, Titan
If you hold down the CTRL key while you drag a junction onto the Workspace and drop onto an existing Workspace junction, the old junction will 'morph' (change) into the new one. Pipes will be connected to the new junction and related data will be copied into the new junction.
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