5 calculation of standard volume and mass – KROHNE ALTOSONIC V EN User Manual
Page 54
ALTOSONIC V
Operating Manual rev02 E
7.30850.34.00
Page 54 of 106
5 CALCULATION OF STANDARD VOLUME AND MASS
The principle of the UFP-V is measuring the volumetric proces flow rate. Integrating this value in time
results in the volumetric proces total.
Often measured quantities are compared. Because of temperature and pressure dependency of the
volumetric proces it can be preferable to convert to more standard conditions:
•
Volumetric standard (1.01325 bar and for example 15°C).
•
Mass
5.1
Volumetric standard
The correction of the volumetric proces to volumetric standard is done according to API/ASTM-IP
standards.
The volume correction factor VCF can be divided into:
•
Correction for the temperature dependency, using API 11.1 standard 2540 equation and constants,
resulting in a correction factor C
tl
•
Correction for the pressure dependency, using API 11.2.1M equation and constants, resulting in a
correction factor C
pl
.
pl
tl
C
C
VCF
⋅
=
VCF
Vol
Vol
proces
d
s
⋅
=
tan
VCF
: Volume correction factor
C
tl
: Temperature correction factor
C
pl
: Pressure correction factor
Vol
stand
: Volumetric standard [m3]
Vol
proces
: Volumetric proces [m3]
Also available after calculation is the density at proces conditions. This means that mass is also
calculated.
5.1.1
Calculation of correction temperature dependency C
tl
The correction for the temperature dependency to the 15°C reference base:
))]
15
(
8
.
0
1
(
)
15
(
[
−
⋅
⋅
+
⋅
−
⋅
−
=
process
T
process
T
tl
T
T
EXP
C
α
α
C
tl
: Temperature correction factor
α
T
: Thermal expansion coefficient [1/°C]
T
proces
: Temperature proces [°C]
In this, the equation is independent of the group or substance. It can be used with any valid method of
obtaining the thermal expansion coefficient for a given fluid, as long as a statistically significant number
of points is obtained. A minimum of ten such points is recommend. In addition, the values of the
constants K
0
, K
1
and K
2
are given for each major group.
These constants relate the thermal expansion coefficient to base density by :
2
15
1
2
15
0
K
K
K
T
+
+
=
ρ
ρ
α
α
T
: Thermal expansion coefficient [1/°C]
ρ
15
: Density at reference 15 °C [kg/m
3
]
K
0
, K
1
, K
2
: Constants, depending on the type of the product
The API table for the 15°C reference base as installed in the UFP-V is: