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Configuration and Use Manual 35
Calibration
Startup ConfigurationCalibrationBefore You Begin
3.5 Performing meter validation
To perform meter validation:
1. Determine the meter factor(s) to use. You may set any combination of the mass flow, volume
flow, and density meter factors.
Note that all three meter factors are independent:
• The mass flow meter factor affects only the value reported for mass flow.
• The density meter factor affects only the value reported for density.
• The volume flow meter factor affects only the value reported for volume flow.
Therefore, to adjust volume flow, you must set the meter factor for volume flow. Setting a
meter factor for mass flow and a meter factor for density will not produce the desired result.
The volume flow calculations are based on original mass flow and density values, before the
corresponding meter factors have been applied.
2. Calculate the meter factor as follows:
a. Sample the process fluid and record the process variable value reported by the flowmeter.
b. Measure the sample using an external standard.
c. Calculate the new meter factor using the following formula:
If you are calculating the volume flow meter factor, note that proving volume in the field may
be expensive, and the procedure may be hazardous for some process fluids. Therefore, because
volume is inversely proportional to density, an alternative to direct sampling and measurement
is to calculate the volume flow meter factor from the density meter factor. This method
provides partial correction by adjusting for any portion of the total offset that is caused by
density measurement offset. Use this method only when a volume flow reference is not
available, but a density reference is available. To use this method:
a. Calculate the meter factor for density, using the preceding formula.
b. Calculate the volume flow meter factor from the density meter factor, as shown below:
Note: This equation is mathematically equivalent to the equation shown below. You may use
whichever equation you prefer.
3. Ensure that the meter factor is between
0.8 and 1.2, inclusive. If the calculated meter factor is
outside these limits, contact Micro Motion customer service.
NewMeterFactor ConfiguredMeterFactor
ExternalStandard
ActualFlowmeterMeasurement
---------------------------------------------------------------------------------
×=
MeterFactor
Volume
1
MeterFactor
Density
-----------------------------------------------=
MeterFactor
Volume
ConfiguredMeterFactor
Density
Density
Flowmeter
Density
ExternalStandard
-------------------------------------------------------
×=