Specify a Pressure Loss Method for Fittings and Accessories for Duct and Pipe

You can specify a pressure loss method for fittings and accessories for duct and pipe in the Properties palette.

Third party developers can create calculation methods installed as add-ins to take the place of default calculation methods within Revit.

To specify a loss method

1. Select a duct or pipe fitting or accessory.
2. In the Properties palette, for Loss Method, select a pressure loss method from the list.
   For duct, the default loss methods are:

   • Coefficient from ASHRAE Table
   • Specific Coefficient
   • Specific Loss
   • Not Defined
   For pipe, the default loss methods are:

   • K Coefficient from Table
   • Specific Coefficient
   • Specific Loss
   • Use Definition on Type
   • Not Defined
   Note:

   • Specific Loss and Specific Coefficient are not available when a fitting or accessory with more than two connectors is selected, because there is more than one pressure loss on the fitting or accessory.
   • Third party developers can develop additional loss methods for fittings and accessories which may appear in this list.
3. When Specific Coefficient or Specific Loss is selected, you can specify a value for the selected loss method. For Loss Method Settings, click Edit.
4. In the Settings dialog, specify a value for the selected Loss Method.
Note: If a duct system is well-connected, the Pressure Drop parameter will report the pressure drop value of this fitting or accessory. If the fitting or accessory has more than one path (more than two connectors), Pressure Drop will display as empty. Note that the Pressure Drop value will include the pressure drop for connectors. For example, an accessory connector has a built-in pressure drop parameter, unlike a fitting. The final pressure drop on an accessory is the sum of the two pressure drop values.