The Bentley storm and sanitary sewer models treat pumps as nodes connected to suction and discharge piping. However, not all solvers were set up with that representation and not all pumps have suction lines (e.g. submersible pumps).

In the GVF solvers, there is no benefit from using virtual pressure pipes. For the GVF-convex solver, they are treated as not virtual even if they were set up as virtual in another solver (with the diameter and length taken from prototype properties). In the GVF-rational solver, no head loss is calculated for the virtual pressure pipes. When moving between solvers, the user should remember that head loss is calculated in the GVF-convex solver so the results may not agree between solvers.

In the implicit solver, pressure pipes connected to pumps may or may not be virtual. When implicit pressure pipes are virtual, no head loss is calculated and the flow is simply moved from the upstream to the downstream nodes on the pipe. For example, a virtual suction pipe can be used to represent a submersible pump which has no suction pipe but is shown with a suction pipe in the drawing.

In the explicit solver, no head loss is calculated for virtual pressure pipes. When a SWMM model is imported into a Bentley model, a virtual pressure pipe is placed on both the suction and discharge side of the pump and the explicit solver is set as the default.

In general, the most accurate calculation of pump flows result if virtual pipes are not used. If they must be used, then they should be kept short in the drawing. For example, in SWMM, it is possible to have the discharge side of a pump connected to a node thousands of feet away with no consideration of the interconnecting force main. This should be avoided if accuracy in pump behavior is important.

When moving a model between solvers, where virtual pipes are used in the implicit and explicit solvers, it is advisable to set up a different physical alternative for the solvers.