Pressure Drops Main Dialog

Main dialog for calculating Pressure Drop

The main dialog for calculating the pressure drop of the duct is launched from the Add-ons tab -> Pressure Drops panel -> Pressure Drops button. The user selects elements for the pressure drop calculation either before starting the tool or is prompted for the selection of elements after the tool is started.

Pressure Drops application on the Add-Ins card

The main dialog displays all entities in the selected path. These properties of each element are displayed:

• Type Name

• Category

• Part Type

• Mark

• Length

• Size

• Cross-Sectional Area

• Velocity

• Flow

• Loss Factor

• Pressure Drop

Which properties are displayed can be setup in the settings dialog.

Pressure Drops main dialog

The only data column that the user can fill in is the "Loss Factor ζ" column. The user does not fill in the loss coefficient for straight pipe sections and flexible piping - pressure drop is calculated automaticall by the application. For the other elements the user enters the coefficient, which is obtained either from the manufacturer's sources, by engineer's own calculation or by other means. The tool writes these coefficients for each element in the CS_LOSSFACTOR parameter during the pressure drop calculation, so these can be later used again.

When the checkbox next to the element is unchecked, the element is not included in the total pressure drop calculation.

The Calculate button starts the calculation of the total pressure loss of the selected route. The resulting pressure drop is displayed in the dialog. The dialog offers a button for copying the calculated pressure drop to the clipboard.

Calculation of the total pressure drop

The pressure drop is calculated using Darcy-Weisbach equasion:

$Lp = ζ * ρ * V^2 / 2$

The application supports pressure drop calculation for rectangular, round and oval ducts.

The Pressure Drops main dialog is non-modal, so the user can work in Revit views along with the open Pressure Drops dialog. In the displayed list of route elements, when an element is double-clicked, it is displayed in the active view.

To select a new route for calculation, the Select from view button is available in the dialog, which allows the user to select a new route.