6 Commissioning Promass 40
30 Endress+Hauser
6.2.3 Density adjustment
Accuracy in measuring fluid density (which is proportional to the resonance of the
measuring tubes) has a direct effect on calculating volume flow. Density adjustment is
not necessary unless the properties of the fluid are outside the reference operating con-
ditions used at calibration.
Performing a density adjustment
Caution:
• On-site 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 fluid density
measured in the device by more than ±10%.
• An error in defining the target density affects all calculated volume functions.
• Density adjustment changes the factory density calibration values or the calibration
values set by the service technician.
The functions outlined in the instructions below are described in detail in the “Descrip-
tion 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 equal-
ised. The time you have to wait for equalisation depends on the fluid and the tem-
perature level.
3. Select the density adjustment function:
PROCESSPARAMETER
→
DENSITY SET VALUE
Enter the fluid's target density and save this value.
Input range = actual density value ±10%
4. Select the “MEASURE FLUID” function.
Select
the “START” setting. A “MEASURING DENSITY” message appears for
approx. 10 seconds on the display. During this time the current density of the fluid
(measured density value) is measured.
5. Select
the “DENSITY ADJUST” function.
Select the “DENSITY ADJUST” setting. Promass compares the measured density
value with the target density value and calculates the new density coefficient.
Caution:
If density adjustment does not complete correctly, you can select the “RESTORE
ORIGINAL” function to reactivate the default density coefficient.
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