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Reference
MVI71-AFC ♦ PLC Platform
Gas and Liquid Flow Computer
Viscosity (cP)
The viscosity of the fluid, used only in the calculation of the meter's coefficient of
discharge.
Isentropic exponent
The ratio of (specific heat at constant pressure) to (specific heat at constant
volume).
Default Fpv
Normally, the AFC uses the "Detail Characterization Method" of the AGA 8
Standard to calculate the compressibilities of the gas from its composition as
given by the molar analysis, which compressibilities are used in all subsequent
calculations. When AGA 8 cannot be applied because no analysis is available
(no components selected, or analysis is all zero), then this value supplies the
supercompressibility (which combines the effects of the compressibilities at both
reference and operating conditions) to be substituted for the output of AGA 8.
K/Meter factor
The primary measured quantity (usually gross volume) is calculated as (pulse
count) divided by (K-factor) and multiplied by (meter factor). One of those factors
(usually the K-factor) is static and is entered here; the other factor (usually the
meter factor) is calculated by interpolating from the table that begins at register
8530, which table in turn acquires its values from one or more meter provings at
different flow rates. For more information, see stream option "Interpolate Kfactor" (register 8500 bit 8).
Default energy content
Normally, the AFC uses the "Detail Characterization Method" of the AGA 8
Standard to calculate the heating value of the gas from its composition as given
by the molar analysis, which heating value is used in all subsequent calculations.
When AGA 8 cannot be applied because no analysis is available (no
components selected, or analysis is all zero), then this value supplies the mass
heating value to be substituted for the output of AGA 8.
Default density at reference
The density at reference conditions ("corrected density") to be substituted for use
in measurement calculations when it is otherwise unavailable because either
(a) density process input is out of range, and both meter calculation options
"Density correction" and "Ignore default flowing density" (register 8025 bits 8 and
7) are set,
or
(b) the density correction calculation fails (for example, if an input to the
calculation is outside the range allowed by the Standard).
ProSoft Technology, Inc.
November 27, 2007
Page 219 of 291