KROHNE ALTOSONIC V EN - Manual (Page 23)

ALTOSONIC V
Operating Manual rev02 E 7.30850.34.00 Page 23 of 106
In the picture method 1 is in light-blue meaning this method is used to make the Reynolds correction
factor Kr.
In the picture method 2 and 3 is in grey meaning this method is not used to make the Reynolds
correction factor Kr.
The green arrow ► at the Kr location shows that this Kr factor is used in the flow calculation. No arrow
means: Not used.
When the correction is on hold due to flow variations this is shown in yellow as HOLD at the Kr
location. During the hold period the corrections are done with the REAL-profile as a reference.
The “Dev AB %” shows the percentage of deviation between measured AL BL pair and closest
interpolated match to AL BL the lookup table. The smaller the deviation the higher the quality of the
Reynolds Correction normally is.
SWIRL shows:
In version 03005000 and later the previous used Swirl Number is replaced by the Swirl% and
Skewness%.as quality parameters on the measured flow profile.
The Swirl % is an indication for the found swirl. A normal value is -3.5%…+3.5%.
Out of this range the swirl is considered to have a influence on the flow measurement accuracy.
The Skewness % an indication for the skewness of the measured flow profile. As Skewness can come
in many different shapes (symmetrical, and assymetrical) it is difficult to put a limit on the allowed
percentage. Skewness is installation specific and can come in many different shapes (symmetrical
and asymmetrical). Determination of a limit should be based on installation experience. Registration of
skewness during start up or during the first few weeks of installation will give insight in the installation
specific limits
It is strongly recommended to avoid swirl by using a flowstraighting device. In the situation whereby
flow straigtners can not be used or are insufficient for the high levels of swirl can not be elimimated the
A-V has option to use a swirl correction factor because swirl influences the profile and as such the
used correction based A and B needs to be compensated for this the swirl correction table can be
used. This correction value if possible should be avoided. Hoewever if swirl is present the result will be
much better neverthelees the accuracy of the A-V will be lowered and as such the A-V may operate
outside its spec.
By default the swirl correction factor is not used.
Only if there is physically no way to correct a swirl it is used to make a more reasonable flow value but
this value is inaccurate. As such the ALTOSONIC V may operate outside its specification to be within
specs of the ALTOSONIC V because of possible uncalibrated swirl intensities and viscosities.
•
The green arrow ► at the Ks location shows that the factor is used in the flow calculation.
No arrow means: Not used in the flow calculation.
•
If the correction is on hold due to flow variations, this is shown in yellow as HOLD at the Ks
location. During the hold period the corrections are performed with the REAL-profile as a
reference.
BODY EXPANSION shows:
The temperature expansion correction is done with the measured Body(Primary) temperature.
The correction factor is Kb. The green arrow
► at the Kb location shows that the factor is used in the
flow calculation. No arrow means: Not used.
The correction for body thermal expansion is as follows:
) ( 3 1
ref body b
T T K − ⋅ ⋅ + = α
K
b
: Correction factor used for the body thermal expansion
α : Lineair thermal correction factor [°C -1 ], depending on the type of metal material.
T
body
: Temperature body [°C]
T
ref
: Temperature reference [°C]
The Kb factor is implement as a normal kfactor to correct the measured volume for thermal body
expansion.
Another option to use (by default disabled) is the pressure expansion correction. Only applicable for
high process pressures. The correction factor is Kbp. The green arrow ► at the Kbp location shows