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9.4 Adjust density measurement with Density Offset
or Density Meter Factor
You can adjust the reported density measurement by modifying the value for Density Offset
or Density Meter Factor. The measured density value is always multiplied by the density meter
factor. The density offset is always added to the result.
The default value for Density Meter Factor is 1.0. The default value for Density Offset is 0.
Accordingly, the default values have no effect on the reported density value.
Important
Density Offset and Density Meter Factor improve measurement accuracy only when the line temperature
and line pressure of the sample are close to the line temperature and line pressure of the process.
Tip
If the density offset calibration procedure is available, use it to calculate a density offset value that is
corrected to reference temperature and reference pressure. Density offset calibration is the
preferred method to adjust density measurement.
Restriction
You cannot enter a density offset from the display. If you want to change the density offset manually,
you must use ProLink III or the Field Communicator.
Prerequisites
You will need an external density measurement method that is highly accurate.
Ensure that your process is stable during the sampling procedure. Minimize variation in
density, temperature, flow rate, and fluid composition. Minimize aeration.
Procedure
1. Take a density reading from the device.
a. Ensure that line temperature and line pressure are at typical operating levels.
b. Record the line temperature and line pressure.
c. Record the measured density.
2. Immediately after the previous step, take a sample from a location as close to the
device as possible.
3. Using the external measurement method, measure the density of the sample at line
temperature and line pressure.
4. Use the following equation to calculate an appropriate value for Density Offset or
Density Meter Factor.
ρ
Lab
=
(
ρ
Line
× DensityMeterFactor
)
+ DensityOffset
Measurement support
142 Micro Motion
®
Fork Viscosity Meters (FVM)