With the program CROSS, closed as well as branched water supply networks can be computed. The program processes following elements: hydrant, slide valve, check valve, source supplies, delivery pits, pressure tank, water towers, flow regulator. The feeding in the net can take place with centrifugal pumps, piston pumps as well as elevated water tank or water tower. Different pressure zones are considered with pressure regulator to increase or decrease the pressure. Additionally 24-hour-simulation is also possible and provides a system layout plan with default coordinates. With the program GraPS the computation output can be graphically evaluated under different topics.
The basis of the calculation is the DVGW leaflet GW 303 "Calculation of the pipeline nets with electronic data processors".
The hydraulic calculations are carried out according to Prandtl-Colebrook formula and the resistance
formula of Darcy. The iterative solution of the nodes and mesh equations takes place in the procedure of "head loss equation" by Kirchhoff.
The network data consists of Node-list, Pipe-list, elevated tank, pumping and pressure change list.
The net can be divided into different sub networks. The sub networks can be computed individually or combinely.
In node-list, ground level elevation and extraction rate should be indicated. In Pipe list, start node and end node, nominal diameter, roughness coefficient value and pipe length are necessary.
The sequential order of input of node and pipe is arbitrary.
Centrifugal pumps are defined by pump characteristics.
An increase in pressure and/or a pressure reduction by a pressure regulator is defined as the relative pressure change in m+NN. In contrast, a constant pressure can be given in m+NN during a pressure control.
An elevated tank is defined by assigning the feeding water level to a node.
As per desire, different cases (operating conditions) can be defined.
Individual elements (e.g. pumps) can be active or inactive in the respective case .
Different variations are possible at the definition of the water extraction: as Node extraction, as Pipe extraction or both in combination. Additional constant quantities of water including water during fire can be taken and computed separately.
In the node list, the quantities of water for a particular case, can be changed by an overall multiplication factor.
For the node extraction, the water extraction (l/s) is entered in the node list at every extraction point. For the distance extraction, a supplying zone (meter-flow value) can be assigned to each pipe.
Apart from case-wise computation, the program CROSS also makes a 24h Serial simulation possible. Variable load profiles are assigned to the individual net elements in the form of hydrograph curves (e.g. time-dependent, variable node extraction, variable pump capacity, and switching off pumps, variable feeding water level of the high container etc.). CROSS offers different variations for the evaluation of the particular computation result of the 24-hour-simulation.
After setting a reference pressure (smallest permissible operating pressure in the case of fire) as well as an additional extraction quantity of water, which are set successively for each node, an automatic fire drop computation can be accomplished.
Data output
Different operating conditions (load cases), as desired, can be stored. The expenditure takes place concerning the contents and format in freely definable lists. The following lists are used:
Application limitations
In a project as many as desired cases can be defined. The supply network can be divided into as many as desired sub networks (e.g. different pressure zones).
Data exchange
The data with CROSS are available in the following programs for further treatment:
| • | GraPS | Graphical planning system for Sewer and Water Supply nets |
| • | CROSSPLOT | Longitudinal profile drawing |
| • | CROSSPLAN | Network plan drawing |
| • | WERTWASSER | Property valuation for Water Supply Network |
Interface diagrams
The data are stored in ACCESS Database format. Different functions are available to import and export:
| • | ASCII | Read data from an ASCII file. The format can vary and can be specified by each of initial position and the number of characters in the specified value to be imported. |
| • | Excel | Data in the Excel format can be imported to and exported from the current project. |
| • | RTF, WMF, HTML | Each resulting list can be exported with the preview to RTF, or HTML WMF format. |
| • | Query Generator | Arbitrary evaluations is made possible for the project data base with the help of Query generator. |