User manual

Toolbox 32 User Manual 1.47d www.cse-semaphore.com/mykingfisher
Page
96
AGA-8 Gas Compressibility (Detailed calculation)
Uses the American Gas Association standard AGA-8 for calculating gas compressibility using the detailed
characterization method. Requires driver AGA8DET.Dxx.
The driver is based entirely on Compressibility Factors of Natural Gas and Other Related Hydrocarbon
Gases, AGA Transmission Measurement Committee Report No. 8, Second Edition, November 1992.
Comment: A 12-character description.
Compressibility: (Float) AGA-8 compressibility factor of the gas.
Status: (Local register) AGA-8 calculation errors and warnings. The following channels are used:
• Ch1: Internal calculation error. The AGA8 Detail calculation is a fairly complicated nonlinear calculation
that includes a couple of iteration loops (ie. it repeats a calculation many times until the result converges
to a solution). The AGA8 driver limits these loops to a maximum of 100 iterations each, to limit the time
taken to perform the calculation. An Internal calculation error indicates that after 100 iterations the result
was still varying slightly (a valid result is still returned by the AGA8 calculation block). The reason for the
variation may be that the input parameters are close to the limits specified in the AGA8 Detailed
specification. For further details about the parameter limits and the tolerance levels, please refer to the
actual AGA8 Standard. If very precise accuracy is required from the result, the internal calculation error
bit can be used as a warning flag, otherwise it can be ignored.
• Ch2: Pressure out-of-range error (allowed range is 0 to 280 MPa)
• Ch3: Temperature out-of-range error (allowed range is -130 to 400
o
C)
• Ch4: Firmware driver error
• Ch5: Gas components outside normal range
• Ch6: Gas components outside expanded range
Temperature (deg C): (Float) Input variable representing gas temperature.
Pressure (MPa): (Float) Input variable representing gas pressure.
Input Components, Molar Fractions: These parameters represent the relative proportions of each
component in the gas mixture. They can be entered in any units (percentages, fractions, etc).