Below are some of the common issues found when constructing models in Pumpsim™. For more help when a warning or error shows, please refer to Appendix E.
The pipe has no flow.
Some common reasons are:
- Presence of an excluded pipe in the line. Select all the pipes in the section and click on EDIT, the "excluded" check box should be unchecked.
- Some pipes might not be properly connected. Use SELECT > ALL to see if all the required pipes are connected.
- The inlet pipe could be connected above the water level of the tank.
More flow is leaving the tank than entering.
During the steady state simulation, all flows are based on the system as it is, the water level will stay the same. It provides data from the tanks at a specific level. The INFO box of the tank will give you information about the filling/emptying rate of the tank. A warning can be shown by changing the tank tolerance (Settings > Flow Simulation); a warning will show if the tank will empty or fill quicker than the tolerance. Setting the tolerance to 0 shows no warning.
During the dynamic simulation, the water level will rise until full, then the water will flow out and be lost from the system. Once empty, no water will come out of the tank.
Why is there cavitation?
Cavitation occurs when the pressure is too low and water vaporizes. It is usually due to a high pressure drop in pipes, which is often linked to a high flow rate. It is likely that a valve or device is missing in the line, often at the end. For example, an open pipe might be missing a demand point or a valve.
It is important to note that the results given when cavitation occurs are likely incorrect. A cavitation problem needs to be fixed for a correct simulation.
How can there be negative pressure?
The pressure is a gauge pressure, it is the absolute pressure minus the atmospheric pressure.