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Overview
Meter validation compares flowmeter measurements reported by the transmitter to an
external measurement standard. If the transmitter value for mass flow, volume flow, or
density measurement is significantly different from the external measurement standard,
you may want to adjust the corresponding meter factor. The flowmeter’s actual
measurement is multiplied by the meter factor, and the resulting value is reported and
used in further processing.
Prerequisites
Identify the meter factor(s) that you will calculate and set. You may set any combination of
the three meter factors: mass flow, volume flow, and density. Note that all three meter
factors are independent:
• The meter factor for mass flow affects only the value reported for mass flow.
• The meter factor for density affects only the value reported for density.
• The meter factor for volume flow affects only the value reported for volume flow or
gas standard volume flow.
Important
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.
If you plan to calculate the meter factor for volume flow, be aware that validating 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 measurement is to calculate the meter factor for volume flow from the meter factor
for density. See Section 9.4.1 for instructions on this method.
Obtain a reference device (external measurement device) for the appropriate process
variable.
Important
For good results, the reference device must be highly accurate.
Procedure
1.
Determine the meter factor as follows:
a. Use the flowmeter to take a sample measurement.
b. Measure the same sample using the reference device.
c. Calculate the meter factor using the following formula:
NewMeterFactor ConfiguredMeterFactor
ReferenceMeasurement
FlowmeterMeasurement
=
x
2. Ensure that the calculated meter factor is between 0.8 and 1.2, inclusive. If the
meter factor is outside these limits, contact Micro Motion customer service.
Measurement support
128 Micro Motion
®
Model 1500 Transmitters with Analog Outputs