Problem

After computing a model that uses the top filling option in one or more tanks, strange results are seen near the tank (such as a high HGL or "system disconnected" message), or the following message is generated:

• "Top filling tank; Invert level is outside the tank operating range. (Tank Minimum Level < Invert Level < Tank Maximum Level)."
• Tank with throttling inlet; Level Inlet Valve Fully Closes must be lower than (or equal to) the Tank Maximum Level."

How is this resolved?

Solution

The invert level entered must fall between the minimum and maximum level, as opposed to the minimum and maximum elevation. If an elevation is inadvertently entered or the level value entered is higher than the tank's maximum level., this error message will result.

Because the inlet invert will be the sum of the base elevation and the inlet invert level. Note that you can switch the type of operating range for the tank in the tank properties. If you change from "Elevation" to "Level" you will be able to quickly check and enter in the correct invert level and verify that it falls between the minimum and maximum level of the tank. You will need to enter a level value that is relative to the bottom of the tank. For instance, if the base of the tank is at 1000 ft and the maximum elevation is at 1010 ft, this will correspond to a "Level" of 10 ft.

In other words, the "level (inlet invert)" needs to be expressed as a distance above the bottom (base elevation) of the tank, not a HGL.

See Also

Modeling top fill tanks and throttling inlet valves