Unit System

You can set the units you prefer to use in AFT Fathom in the Unit System section. Once selected as the preferred units, these units appear as the default units in all instances in which empty fields exist in the model input. Any model input existing prior to changing the Preferred Units will maintain the units used when the data was input, regardless of changes made to unit preferences. After saving your preferred units, a window appears asking if you would like the output parameters to be displayed in your preferred units. Choose Yes if you do want the output parameters to be displayed in the preferred units, or No if you want the output parameters to be displayed in the units used prior to making changes to the preferred units.

Preferred Units

To customize the units used by AFT Fathom, first select Preferred Units under the Unit System section in the User Options window under the Tools menu.

AFT Fathom allows you to specify certain units from a large selection to be displayed in the main interface.

The primary selection is the Unit System:

  • US - Only US units will be available

  • Metric - Only Metric units will be available

  • Both with US Defaults - All Units will be available, but US units will be chosen by default

  • Both with Metric Defaults - All Units will be available, but Metric units will be chosen by default

Additionally, a filter can be applied to limit the selection:

  • All Units - all units for the Unit System will be displayed

  • Common Only - only "common" units will be displayed

  • Common Plus Selected Industries - Units particular to certain industries can be included with the common units

If the selection has been limited to Common Only, there may units common for certain industries no longer present. The Additional Units for Industry section allows the user to append additional sets of units to the Common unit set. For example, barrels/day is a common unit in the petroleum industry but not many others. Checking the Petroleum box adds these units to the main interface.

Preferred Units allows fine grain control over what unit in the above selection is displayed as the default when defining model input. For example, it may be desired to have a particular parameter such as pipe diameter default to inches, while keeping other parameters metric. This area allows the user to define such defaults.

Show/Hide Unit Items

For additional control of the available units, select Show/Hide Unit Items under the Unit System section. From here, you can select which units for each Unit Family Type you would like to be available for the model input and output by checking the box next to each unit you would like to be used. Removing units that you do not wish to use as input or view as output can simplify your modeling and reduce errors associated with incorrect units.

Edit Custom Unit Names

A custom unit name can be assigned to display different names in the interface for units. For example "feet/min2" could be changed to display as "ft/min2."

To assign a custom unit name choose the appropriate Unit Type from the drop-down and enter the Custom Unit Name in the table.

To speed up the process of entering custom unit names the units can be exported to csv and re-imported as follows:

  1. Click "Save Units to CSV" and save the file where it will be easy to locate

  2. Open the CSV file in a spreadsheet editing software like Excel, and fill in the desired custom unit names in the Custom Name column

  3. Save the CSV file

  4. In the User Options window click "Load Units from CSV" and select the edited CSV file

Note: To use units with superscripts, make sure the csv file is saved with UTF-8 encoding. This can be done in Excel by choosing save as and selecting "CSV UTF-8" as the file type.

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