For the calculation of the pipe network, it is necessary to enter the characteristics of the network which consist of pipes and nodes.

Note: In order to make easier the entry of data on the pipe network, I suggest that you first draw a sketch of the pipe network and mark all the pipes and nodes.

Pipes

For each pipe, it is necessary to enter its ID (integer greater than 0), inner diameter, length, and the roughness of the inner surface. It is also necessary to specify the ID numbers of two nodes that this pipe connects for each pipe. Actual flow direction from one node to another will be calculated and presented after calculation in terms of the arrow pointing from one node ID to another.

Nodes

Nodes are points where two or more pipes join. If the system contains a tank or pump, such places are defined as nodes.

There are two types of nodes.

Fixed pressure nodes - reservoirs and pumps

The first type are nodes where the pressure is constant and in such nodes, the pressure is not calculated - they are e.g. tanks or pumps. For pumps, it is necessary to insert two nodes with constant pressure in front of and behind the pump, and not to insert a pipe between those two nodes. All nodes of this type must be numbered with ID = 0. It is normal to have multiple nodes with ID=0 - like in the system with two or more reservoirs and pumps. This group of nodes are not required to be entered in the table “List of nodes”. Nodes with ID=0 are not possible to enter in the list.

Calculated pressure in nodes - where pipes meet

The second type is nodes in which two or more pipes connect and in which the pressure is the subject of calculation. Optionally, from this type of node, the volume of the flow that flows out of the node can be specified, and this volume is considered constant in the calculation. Normally, the amount of fluid that flows into the node and that flows out of that node is the same. All nodes of the second group must be numbered with an integer greater than 0 (1,2,3,4…).

This group of nodes are required to be entered in the table “List of nodes”.

For all nodes of the second group, it is necessary to enter the assumed pressure values in the node itself. These are the initial values, and the actual values ​​will be displayed after the calculation. It is correct to enter the pressure values ​​that are between the pressures set in the nodes of the first group. For example, if the pipe network between the tank with a constant pressure of 2 bar and the pipe is open to the atmosphere with an overpressure of 0 bar, then it can be assumed that in the nodes in the pipe network the pressures will be from 1.9 bar to 0.1 bar moving from the tank to the pipe that is open atmosphere.