The following pipes have vapor volumes in computing stations greater than 10% but less than 100% of the liquid computing volume

Full Message Text

The following pipes have vapor volumes in computing stations greater than 10% but less than 100% of the liquid computing volume:

Pipe X (Name), Stations: Y (Z%)

Explanation

This Warning is part of a series of Output Messages meant to convey increasing uncertainty in results as Percent Vapor Volume increases.

Caution - greater than 0.1% but less than 10%
Warning - greater than 10% but less than 100%
Critical Warning - greater than 100%

A detailed explanation about the Percent Vapor Volume parameter, section volume, and assumptions can be found on the Interpreting Cavitation Predictions topic. In summary, Impulse's solution methodology assumes that pipe sections are 100% liquid-full. This warning is stating that for the listed pipe stations, the Percent Vapor Volume was greater than 10% but less than 100% of the section volume at some point during the transient, which is violating the 100% liquid-full assumption to a substantial degree.

Vapor volumes between 10 and 100% of the section volume indicate that major transient cavitation is occurring at that point in the system. Impulse's cavitation models are meant to capture limited transient cavitation in a system, and have limited accuracy as vapor volume increases. Depending on the system, this amount of transient cavitation may be a cause for concern since it can lead to additional waterhammer effects.

Required Action

Users should explore the various cavitation topics - and in particular the Interpreting Cavitation Predictions topic - to better understand what is causing these results, why they are possible, and how to interpret results in scenarios seeing this warning. If all else fails, users should treat systems with these results with caution, and incorporate large safety factors into their designs.