Tank
The Tank junction type allows you to connect up to twenty-five pipes. One connecting pipe is required. The Tank junction is convenient for specifying a fixed pressure in your system.
A Tank junction applies a defined pressure and temperature at the junction location in the model. When solving a pipe flow system, a Tank causes the rest of the system to distribute the flow in a manner consistent with the defined pressure.
The Tank Properties window follows the second of the two basic Properties window formats. A table on the Loss Coefficients folder tab displays the connecting pipe information. This table grows to accommodate up to twenty-five pipes. After you add a fifth connecting pipe, a scroll bar appears, allowing you to review and enter loss factors for all pipes in the table.
The pipe table displays the reference positive flow direction of each connecting pipe. To enter loss factors, select the cell in the table and edit the value. Each pipe can use a different loss model or custom value.
Energy Balance
For an open system, most users desire that the temperature remains fixed, like the pressure does. However, for closed, recirculating systems, you will usually want the temperature to vary. See Open vs. Closed Systems - Balancing Energy for detailed discussion.