ProSoft Technology MVI56-AFC - Manual (Page 277)

MVI56-AFC ♦ ControlLogix Platform Reference
Liquid and Gas Flow Computer User Manual
ProSoft Technology, Inc. Page 277 of 316
February 25, 2011
Pressure Correction Factor, CPL
The CPL(Flowing / UserBase) is calculated according to the method given in
MPMS Ch 12.2 1995. In order to correct "density at reference" to User Base
conditions, and also when iteratively calculating corrected density for the effect of
elevated pressure, the CPL(Flowing / ApiBase) (unrounded) is also calculated
according to the same method.
Density Correction
The density at API Base is determined according to relevant standards, which
density is used as input to the CTL and CPL calculations. The density at User
Base is determined by multiplying den(ApiBase) by the term (CTL(UserBase /
ApiBase) * CPL(Flowing / ApiBase) / CPL(Flowing / UserBase)), all unrounded
factors; this density is reported only and is not used in any calculations. When
density correction is not selected, or an alarm causes a default to be assumed,
any default "density at reference conditions" is deemed to be at User Base, and
is also corrected to API Base for input to the CTL and CPL calculations.
Archiving and Event Log
a) Accumulation and data recording for gas-phase archives conform to the
requirements of API MPMS Ch 21 sec 1, 1993. Liquid-phase archives
conform to API MPMS Ch 21 sec 2.
b) Event-logging conforms to the requirements given in the Industry Canada
Weights and Measures Board Draft Specification "Metrological Audit
Trails" of 1995-03-01
14.2.2 Liquid Correction Factor Details
For firmware version 2.05 and later, correction factors for most liquids are
calculated according to the 2004 edition of API MPMS Chapter 11.1, enhanced
with additional CPL calculations if required in order to allow selection of a non-
standard base (reference) pressure. For lighter liquids (NGLs and LPGs), to
which the 2004 Chapter 11.1 does not apply, the CTL and density correction
calculations of GPA TP-27 are enhanced with the incorporation of the CPL
calculations of MPMS Chapters 11.2.1 and 11.2.2 in a manner analogous to the
method of the 2004 Chapter 11.1, to permit density correction to account for the
effect of pressure and to yield the combined correction factor CTPL. For all
liquids the option is available to use the vapor pressure correlation of GPA TP-15
June 1988.
For firmware version 2.04 and earlier, correction factors are calculated as
described in the following paragraphs.
Temperature Correction Factor CTL
(According to Several "Tables" of MPMS Ch 11.1 (1980, except E Tables 1998 =
GPA TP-25) and Other Standards)
Calculation of CTL (= VCF, Volume Correction Factor) from flowing temperature
and density at standard temperature depends on the measurement system (SI or
US), the product type (crude or refined), and the density range (high or low).