The Compressibility Calculation Type

Depending on the system setup, a Realflo-enabled SCADAPack controller can provide one of these industry-standard gas compressibility calculations:

• AGA-8 (1994) Detail—A detailed gas compressibility calculation. This is the recommended calculation for systems that can support this type and are using flow computers prior to Realflo version 7.02.1.

  This option is not available if the Type of gas flow calculation is set to 'AGA-9' on the Flow Calculation tab.

• NX-19—A gas compressibility calculation for use on older applications that do not support AGA-8 calculations.

  This option is not available if the Realflo-enabled controller on which the Flow Run is located is a SCADAPack x70 controller. This is indicated by the controller's Firmware Type being set to 'x70' (see Specify the Firmware Type in the Geo SCADA ExpertGuide to the SCADAPack Modbus Driver).

• AGA-8 (2017) Detail—Supported by Realflo version 7.02.1 onwards. A detailed gas compressibility calculation that uses the same calculation as the AGA-8 (1994) Detail option, but with different limits for the parameters.
• AGA-8 (2017) GERG—Supported by Realflo version 7.02.1 onwards. A gas compressibility calculation that is based on the GERG2008 equation of state.

The Type of calculation that a Flow Run performs is read into Geo SCADA Expert when the server establishes communications with the controller on which the Flow Run is located. You can also specify the calculation Type manually, if required. For example, if a Flow Run’s data is to be used on report(s), and you want to configure those reports to include the relevant data fields, before Geo SCADA Expert establishes communications with the controller on which the Flow Run is located.

The Type field at the top of the Compressibility Calculation tab indicates the type of compressibility calculation that a Flow Run performs.

The type of calculation that a Flow Run performs determines the fields that are displayed on the rest of the tab.

If the Compressibility Calculation Type is NX-19, the tab displays fields that show the General NX-19 Calculation Properties.

If the Compressibility Calculation Type is one of the AGA-8 options, the tab displays fields that show the:

• General AGA-8 Calculation Properties
• AGA-8 Gas Composition Properties
• AGA-8 Hexane Properties
• AGA-8 Relative Density and Heating Value Properties.