Device

Check valve: For what reason the check valve (in Water) has become a subnetwork controller?

•The check valve is a special type of shut-off device which only allows flow in one direction. Very often these are installed in structures and plants (normally because of space requirements and maintenance) to prevent backflow from a system. Clarifications have shown that check valves were only extremely rarely installed and collected in the current GIS systems. In some cases there are structures that indicate that one or several check valves were installed at this location. These are, for example, transfer manholes with one-sided delivery, where the direction of delivery specifies how the valve was installed. In this context, the pump stations should also be mentioned. In any case, these have to prevent the storages (towers) from emptying again.

•The check valve is like a pressure-reducing valve which also allows only one flow direction. On one side it is a delivery point and on the other side it is a source for the subnetwork. At the same time, this approach also reduces complexity, so that only the feeding elements are available as subnetwork controllers for supplies. In a cascading network that has several check valves in series, it may be that all subnetwork controllers define the subnetwork. In the process, the interrelationships very quickly become complex and confusing. For this reason, the check valve was treated like the gate valve. The following diagram shows a section with the implementation of check valves and the arrangement of the transfer point:
Transfer points (orange), pump stations (PS), reservoirs (T), supply territories (grey), water lines (blue), check valves (red)

•Internal analysis of customer data has shown that few check valves have been collected in the past. The evaluation in the existing projects has shown the following:

oSwitzerland: In approx. 35 projects less than ten objects

oGermany A few dozen.

•In order to remain as flexible as possible in the collection, the check valve was nevertheless implemented as a subnetwork controller. This can be defined/collected, but does not have to be. Here the user is free to decide whether to use the check valve or the transfer point. It is also conceivable that both objects are used. More information on this can be found in the collection guidelines, which are still being developed.