Understand tank boundaries

Tank boundaries are the absolute and normal operating limits. For more information, see Configuring the Tank Configuration Tab of the Tank Record.

The level and volume values exist as separate fields, but they can be considered together since both level and volume indicate the same height in the tank. When entering a value in the Advanced Database Editor (ADE) or the Controller's display for either a level or a volume, the other value not entered will automatically populate using a strapping table lookup. As a result, the values will need to be edited if changes to the strapping table are made.

Maximum Physical Level and Maximum Physical Volume values represent the highest point in the tank, above which overflow will occur. These values are typically set to the same values as the highest entry in the strapping table. While the Maximum Safe Volume and Minimum Safe Volume, and Maximum Safe Level and Minimum Safe Level values define the range in which normal tank operations occur. The Maximum Safe is treated as the full point, and the Minimum Safe is the empty point. The available volume and tank room are calculated in reference to these limits. Warning alarms for these values are configured in the Targets tab, and enabling these alarms is done in the Alarming tab. The Minimum Physical Level and Minimum Physical Volumes are always zero, and as such, these values do not have fields and are not configured.

Validation is done on both tank levels and volumes to ensure that they do not exceed the physical boundaries of the tank. If a reading indicates that the level is negative or has exceeded the Maximum Physical Level or Maximum Physical Volume, it is treated as an instrument failure. The level and volume cannot be updated until the reading returns to normal within the physical boundaries. During an instrument failure condition, AVEVA Enterprise SCADA generates an instrument failure alarm and uses the last good level or volume for the abnormal tank record. For more information, see Understand tank Instrument Failure alarms.