FMC Corporation - Talstar 80 - Handbuch (Seite 64)

Commissioning Proline Promass 80 PROFIBUS PA
64
6.7.2 Density adjustment
Accuracy when determining the density has a direct effect on volume flow calculation. Density
adjustment is thus necessary under the following conditions:
• The sensor does not measure exactly the density value that the user expects on the basis of
laboratory analyses.
• The fluid properties are outside the measuring points set at the factory, or the reference operating
conditions used to calibrate the measuring device.
• The system is used exclusively to measure a fluid’s density which must be registered to a high
degree of accuracy under constant conditions.
Performing a 1-point density adjustment
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Caution!
• Onsite density adjustment can be performed only if the user has detailed knowledge of the fluid
density, obtained for example from detailed laboratory analyses.
• The target density value specified in this way must not deviate from the measured fluid density
by more than ±10%.
• An error in defining the target density affects all calculated density and volume functions.
• Density adjustment changes the factory density calibration values or the calibration values set by
the service technician.
• The functions outlined in the following instructions are described in detail in the "Description of
Device Functions" manual.
1. Fill the sensor with fluid. Make sure that the measuring tubes are completely filled and that
liquids are free of gas bubbles.
2. Wait until the temperature difference between fluid and measuring tube has equalized. The
time you have to wait for equalization depends on the fluid and the temperature level.
3. Select the density adjustment function:
HOME
→ F → R → PROCESS PARAMETERS → F → DENSITY SET POINT
– When you press P you are automatically prompted to enter the access code if the function
matrix is still disabled. Enter the code.
– Now use P to enter the target density of your fluid and press F to save this value (input
range = actual density value ±10%).
4. Press F to select the "MEASURE FLUID" function.
With P, select the "START" setting and press F. The message "DENSITY ADJUST RUNNING"
then appears on the display for approx. 10 seconds. During this time Promass measures the
current density of the fluid (actual density value).
5. Press F to select the "DENSITY ADJUST" function.
With P, now select the "DENSITY ADJUST" setting and press F. Promass now compares the
target and actual density values and uses this information to calculate the new density
coefficients.
"
Caution!
If the density adjustment does not complete correctly, you can select the RESTORE ORIGINAL
function to reactivate the default density coefficients.
6. Back to HOME position with Q (press P simultaneously).