DX0 - Non-Redundant Quantity Indicator

The DX0 - Non-Redundant Quantity Indicator index quantifies the amount of flowing material that is not subject to redundancy checking, that is, the solvability value is not R (redundant). It is based on redundant metered flows, redundant transfers, and redundant inventory gauge differences, and is expressed as a percentage. The operating target of less than 20% – 30% unchecked measurement is desired. If the DX0 index is more than 50% then it may not be possible to detect measurement error with accuracy. You need to add additional measurements whether they are real physical instruments or pseudo measurements that are derived from a calculation. A DX0 value of 0 % implies that every measurement is redundant, which is highly unlikely in a plant environment.

DX0 is calculated by the following equation:

Where:

I = ith flow/transfer/inventory that is in service.

|QR| = Absolute value of the measurement that is redundant.

|Q| = Absolute value of the measurement of flow/transfer/inventory. The reconciled value is used if there is no measurement.