Volume ratio check

The Volume Ratio is the volume calculated in the field (Vref) divided by the volume calculated by the Measurement host (Vcalc). You can use the Volume Ratio to flag or replace volumes in Measurement. Depending on the type of meter configured, these settings are accessible on the Properties for Meter window: Orifice EFM tab, the Corrector Meter tab, and the Pulse EFM tab.

If the Remote Terminal Unit (RTU) reports a volume, but the host cannot calculate a volume, the volume ratio will be set to 1.0 and a problem item appears on the Problematic Context for Meter window with the following message: "Volume Ratio (Vcalc = 0)". The situation arises when either:

• The flowing parameters, such as Differential Pressure for an Orifice meter, are 0.

• A pulse count is 0.

• Configuration is incorrect.

• Gas quality issues exist.

If Auto replace (when Vcalc = 0) is selected, then:

• The value from the RTU is saved in the audit trail.

• The new volume is set to 0.

• The volume ratio is set to 1.0.

• The system generates a problematic context record with the following message: "Volume Ratio Check (Vcalc = 0)(auto replaced)".

If the RTU does not report a volume, but the host can calculate a volume, the volume ratio will be set to 1.0 and a problem item appears on the Problematic Context for Meter window with the following message: "Volume Ratio (Vref = 0)". The situation arises as a result of either a flow cutoff in the RTU, or the inability of the RTU to calculate a volume.

If the Auto replace (when Vref = 0) is selected, then:

• The volume is replaced by the calculated volume.

• The system generates a problematic context record with the following message: "Volume Ratio Check (Vref = 0)(auto replaced)".

When the Volume Ratio can be calculated (both Vref and Vcalc are present), the value is compared to the high and low thresholds. If the value is outside the thresholds, the system generates a problematic context record with the following message: "Volume Ratio".

If Auto replace (outside threshold) is selected, then:

• The value from the RTU is saved in the audit trail.

• The new volume is set to the calculated volume.

• The volume ratio is set to 1.0.

• The system generates a problematic context record with the following message: "Volume Ratio (auto replaced)".

  Note: In the event that you manually entered a zero on the Meter Data Editor, the system automatically assumes that the information entered is correct. Accordingly, an auto replace will not be performed during the Volume Ratio Check.