The air volume entering through Junction X exceeds the volume of a connected pipe

A Critical Warning message in AFT Impulse.

The air volume entering through Junction X exceeds the volume of a connected pipe. The air valve can only model air in a connected pipe. Results with more than 100% air volume are unreliable.

If there are two connected pipes this warning will always apply to the pipe with the smaller volume.

Impulse's solution method assumes that the pipes are liquid full. If the volume of air in the system has not exceeded the volume of a single pipe station, then the liquid full assumption only has a minor impact on accuracy. However, if the volume of air entering the system exceeds the volume of a computational section then the liquid full assumption will cause a larger decrease in accuracy. Impulse uses an adjusted solution method to account for the air entering at the air valve, but does not account for air traveling past the pipes connected to the air valve. Any calculations past the point that the air volume exceeds the connected pipe volume will be invalid.

It is recommended to review the model inputs. Depending on how the air valve and physical system is configured it may be useful to consider changes such as modeling the air valve inline (with two pipes connected), resizing the valve, or moving the valve to a different location.

Modeling the air valve as inline helps to eliminate the potentially short connecting pipe, which will improve model run times and allow the air valve to be attached to longer pipes. Resizing or relocating the air valve can help to reduce the amount of air let into the system and can help reduce operational issues due to entrapped air.