About the isolation trace
The isolation trace is used to determine the nearest valves to be closed in order to isolate one or more selected pipes. The trace works outwards from selected links until the tracing tool reaches pre-defined boundary points.
The isolation trace tool uses the Isolation Trace dialog.
The method is described in Carrying out an isolation trace.
Modes
The isolation trace can be run in two modes:
- Interactive - Each branch of the trace will stop when it reaches pipes that are assumed closed or the limits of the network. If there are no supply nodes (reservoir, fixed heads, transfer-in nodes) in the sub network accessible via the link, the whole of the sub-network is included in the set of links affected. Otherwise, you will be asked to indicate if the link is closed off at either end.
- Non interactive - In this mode you can specify which valve types are to be used as boundary valves. The trace will work outwards from selected links until it reaches pipes that are assumed closed, the limits of the network, or boundary valves.
A maximum of thirty nodes can be included in an isolation trace. A message is displayed if this number is exceeded.
Boundary points
There are several types of node that you can optionally choose as boundary points where the trace will assume a pipe can be closed and will therefore stop. These are:
- Transfer nodes
- Fixed head nodes
- Reservoir nodes
- Well nodes
- Area change
Isolation trace assumes that all pump, meter, and valve links are available to be closed for isolation purposes. If there is control data, isolation trace will take account of closed links, identifying them as links “assumed to be closed”.
You can also define a selection of links that are to be assumed as available to be closed for isolation purposes. This can be used in addition to, or instead of, using the boundary point options.
Transfer nodes
A Transfer Node Status dialog is used to view the demand associated with transfer nodes in the network and to control whether a transfer is regarded as a demand or a supply.
- With control data - InfoWorks WS Pro sets a default based on flow direction at the node (negative flow is treated as demand, positive flow is treated as supply). The treated as default can be overridden via a drop-down menu.
- Without control data - If control data is not open, InfoWorks WS Pro treats all transfer nodes as a demand by default. The treated as default can be overridden via a drop-down menu.
Area change
The Area Code field specified for nodes will often be used to identify different district metered areas (DMAs) or other operational divisions in the water supply system. You can define a boundary by a change in Area Code field, even if there is no valve / closed link modelled at that boundary.
Isolated objects
You can specify which objects are to be isolated on the network. The isolation trace will start from the link(s) in this selection.
Closed links
If there are some links that are known to be closed prior to the use of the isolation trace tool, these can be specified.
Valves to ignore
It is assumed that links can be closed at a valve. If you do not want to make such an assumption, you can specify the valve to ignore. In interactive mode, this means that you will be asked if you want to close the corresponding link or leave it open.
Downstream valves
By default, it is assumed that valve closure can occur at links whose closure would cut off a supply of water to the area being isolated. In interactive mode, this means that you will only be prompted to take an action on links located on the upstream side of the pipe(s) being isolated.
Alternatively, the isolation trace can be made to prompt for valve closure for all specified links whose closure would cut off the area to be isolated, regardless of whether any water is supplied via such a link. This means that you may also be prompted for downstream links.
Markers
Temporary markers can be chosen to be displayed on the GeoPlan at links identified as assumed closed and to be closed during the isolation trace process.
The default is to have no marker information.
Markers are temporary and will be discarded when the trace is reset or when the GeoPlan is closed.
Customer points and spatial data selection
The trace selects and highlights all nodes and links that will be isolated on the GeoPlan. Customer points and/or spatial data that will be isolated can be added to the selection.
Reports
Items can be identified for inclusion in an HTML report that can be requested.
For detailed information on report options available in the isolation trace, see Report Options dialog.
Warnings
When the trace has not managed to successfully isolate the desired objects, having exhausted all the possibilities, a warning message is displayed to the user.
