Flow-X─ Function Reference
4-169
Flow-X General functions - fxASTM_D1555_Dens60F
Equilibrium
pressure
The equilibrium pressure is considered to be
0 psig for liquids which have an equilibrium
pressure less than atmospheric pressure (in
compliance with API MPMS 12.2 par.
12.2.5.4)
psig
0..2000
0
Function
outputs
Remark
EU
SW tag
Alarm
Fallback
Status
0: Normal
1: Input argument out of range
2: Calculation error
3: No convergence
-
STS
FIOOR
CALCERR
Density at
60°F
g/cc
DENS60
0
F
Compressibility factor
The output value will be either
rounded or not depending input
'API 11.2.1 rounding'
1/psi
F
0
CTL
Volume correction factor for
temperature.
Value will be rounded according
to input 'ASTM D1555 rounding'
-
CTL
1
CPL
Volume correction factor for
pressure
Value will be rounded according
to input 'API 11.2.1 rounding'
-
CPL
1
ASTM D1555
calculation
out of range
With respect to ASTM D1555 the
temperature value is:
0: In Range
1: Out of Range
ASTM_OOR
0
API 11.2.1
calculation
out of range
With respect to API 11.2.1 the
conditions of density,
temperature and pressure are:
0: In Range
1: Out of Range
API_OOR
0
Calculations
ASTM D1555 contains both formulas and tables for the Ctl (called VCF in the standard) for the different
product. Please note the formulas are the standard and not the tables. This function therefore applies
the formula to calculate the Ctl value.
The function performs the following iterative algorithm to calculate the relative density at 60
°
F and 0
psig. No rounding is applied
1.
At the start of the iteration the density at [60
F, 0 psig] is set equal to the
observed density and the CPL value is set to 1.
2.
The density corrected for pressure is calculated by dividing the observed density
by the CPL value.
3.
The CTL value and the density at [60
F, equilibrium pressure] is calculated from
the density corrected for pressure and the observed temperature according to
ASTM D1555
4.
The compressibility factor F is calculated according to API MPMS 11.2.1 from the
density at [60
F, equilibrium pressure] and the 'Observed temperature'.
Depending on setting ‘API 11.2.1 rounding’ the rounding and truncation rules of
API 11.2.1 are applied for this step.
5.
The CPL value is calculated from the calculated compressibility factor and the
'Observed pressure' input value.
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