Density Adjustment - Endress+Hauser Proline Promass 84 MODBUS RS485 Operating Instructions Manual

Commissioning
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66
6.4.2

Density adjustment

It is advisable to perform a density adjustment when optimum measuring accuracy is required for
calculating density dependent values. The application may require a 1-point or 2-point density
adjustment.
1-point density adjustment (with one fluid):
This type of density adjustment is necessary under the following circumstances:
• 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.
Example: Brix density measurement for apple juice.
2-point density adjustment (with two fluids):
This type of adjustment is always to be carried out if the measuring tubes have been mechanically
altered by, e.g. material buildup, abrasion or corrosion. In such cases, the resonant frequency of the
measuring tubes has been affected by these factors and is no longer compatible with the calibration
data set at the factory. The 2-point density adjustment takes these mechanically-based changes into
account and calculates new, adjusted calibration data.
Performing a 1-point or 2-point density adjustment
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.
• The 2-point density adjustment is only possible if both target density values are different from
each other by at least 0.2 kg/l. Otherwise the error message #731 (adjustment is not possible)
appears on the display.
• 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. Using the local display, select the SETPOINT DENSITY function in the function matrix and
perform density adjustment as follows:
Function Function name
No.
6482 DENSITY ADJUST MODE
6483 DENSITY SET VALUE 1
Proline Promass 84 MODBUS RS485
Setting to be selected ( S or O )
(to next function with F )
Use P to select a 1- or 2-point adjustment.
!
Note!
When you press P you are automatically prompted to enter the access
code if the function matrix is still disabled. Enter the code.
Use P to enter the target density of the first fluid and press F to save
this value (input range = actual density value ±10%).
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