Update the backwards compatibility overrides

CD_EXCLUDE_O2_FROM_HV

You can use this setting to exclude O2 from the heating value calculation. The setting works by setting the O2 value to zero when calculating the heating value. By default, the setting is disabled.

If you want to enable this:

• Set the booleanValue for CD_EXCLUDE_O2_FROM_HV to Y.

CD_CALCLIB_AGA_3_92_PART_3

You can use this setting to enable the part 3 implementation of AGA-3 1992 specifications. Previous versions of the measCalc library made some assumptions about part 3.

This is enabled by default. You should only disable this setting if you want your calculations to be performed as they were previously, even though they were found to be inaccurate.

If you want to disable this:

• Set the booleanValue for CD_CALCLIB_AGA_3_92_PART_3 to N.

CD_CALCLIB_USE_CONSTANT_ZAIR

You can use this setting to disable the use of a constant value (0.999590) for the compressibility of air in the calculations.

This is enabled by default.

Previous versions of the measCalc library have calculated this using the AGA-8 1992 virial-type but it is felt that the proper implementation is to use a constant. If you want your calculations to be performed as they were previously (despite the fact that they are not used widely in the industry), you can disable the setting.

If you want to disable this:

• Set the booleanValue for CD_CALCLIB_USE_CONSTANT_ZAIR to N.

CD_INCLUDE_H2O_HEATING_VALUE

If you apply the Water Vapour Correction Factor (WVCF) to the Heating Value, presently the calculation is performed as follows as per GPA-2172 1992:

Ewet = Edry * WVCF

If you wish to perform the calculations in GPA-2172 1985 as described below, it is possible to do so:

Wet HV = Dry HV * WVCFactor + 50.312 * (1-WVCFactor)

Ewet = Edry * WVCF + Vdry(1-WVCF)50.312

The first calculation above has been determined to be the correct one by GPA and should be used.

The second calculation is provided in case there is a contractual obligations to be backwards compatible and use the obsolete calculation.

Accordingly, this is disabled by default. We anticipate that this will never be set to Y.

If you want to enable this:

• Set the booleanValue for CD_INCLUDE_H2O_HEATING_VALUE to Y.

CD_REALTIME_2025_OR_NEWER

This is turned on by default. In the event that you are using the 2024 SP1 version of AVEVA Enterprise SCADA, you will need to turn off the setting by changing the booleanValue to N.