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Lookup Tables Revit mep

One coded parameter that is unique is the Lookup Table Name parameter. This parameter exists in some families and can utilize a lookup table for dimensions. These are primarily duct, conduit, and pipe-fitting families. When you install Revit MEP 2012, an extensive library of lookup tables is installed that can be referenced by families.
Lookup tablesare CSV files that work like a type catalog. They provide values for dimensions based on other dimensions within the family. The data in lookup tables can be driven by design codes or manufacturing standards to ensure the graphical accuracy of your components. Pipe fittings, for example, have a nominal diameter that is used to identify the size, but the actual
outside diameter is slightly different, especially for different pipe materials. A lookup table can provide the outside diameter dimension for each nominal diameter that exists in the table.
The Lookup Table Name parameter is used to identify which CSV file the family is referencing.
The location of your lookup tables is defined in your Revit.inifile. When you type in the name of a lookup table, you do not need to include the full path to the file, only the name and file extension. As with parameter names, referencing a lookup table name is case and context sensitive.
Once you have referenced the lookup table with the Lookup Table Name parameter, you can access the data in the table by using a formula for the value of a parameter. The formula using lookup table data is as follows:
text_file_lookup(Lookup Table Name, “Column Name”, Value if notfound in table, Value found in table)
The result of this formula will apply the value found in the table to the parameter, or will apply the defined value given in the formula if none is found in the table. The following image is the formula used to determine the value of the Fitting Outside Diameter (FOD) parameter of a pipe-fitting family. The FOD column is searched for a value that coincides with the value given
for the Nominal Diameter and applies it to the FOD parameter. If the Nominal Diameter value given in the family does not match one in the table, then the Nominal Diameter + 1⁄8″is used for the FOD.

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For more information on working with parameters in family files, see the Families Guide, which can be accessed from the Autodesk WikiHelp site under Revit English 2012 Help Revit User’s Guide Build the Model Revit Families

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