Calculated specific gravity check

The Calculated Specific Gravity Check detects errors in field equipment specific gravity calculations.

This check is performed after data is loaded into the tables, and only if the following conditions are met:

• New Heating Value or Composition Data is available.

• The new data passed the Gas Composition Normalization Check.

• Gas Quality Site is active.

This check applies to any Specific Gravity measurement that has associated compositional data. The following algorithm is used to detect errors in the calculations:

Where:

• SG = Specific gravity of gas stream.

• Comp i = Gas component percentage i in gas stream.

• SGi = Specific gravity associated with component i component specific gravity reference: GPA 2145.

• Zb(gas) = Base supercompressibility of the gas (using AGA-8).

• Zb(air) = Base supercompressibility of air (constant).

• Tol = Tolerance (% error) acceptable for the data check.

The algebraic sum of the specific gravities of each gas component should be equal to the telemetry value for specific gravity, within set tolerances. If the algorithm returns a true condition, an alarm and event are generated and a request is made for a Specific Gravity estimation.

The processing will continue regardless if the outcome is true or false. If the check fails, a specific gravity problematic context is generated.