Prerequisites
Ensure that the active matrix is the one that you want to trim. You can set the offset separately for each matrix
on your transmitter.
You must be able to take a sample of your process fluid and obtain a laboratory concentration value at line
density and line temperature.
Procedure
1. Take a concentration reading from the meter, and record line density and line temperature.
2. Take a sample of the process fluid and obtain a laboratory value for concentration at line density and
line temperature, in the units used by the meter.
3. Subtract the meter value from the laboratory value.
4. Enter the result as the trim offset.
• Using ProLink III: Choose Device Tools → Configuration → Process Measurement → Concentration
Measurement, set Matrix Being Configured to your matrix, and enter Trim Offset.
• Using a field communicator: Choose Configure → Manual Setup → Measurements → Optional Setup
→ Conc Measurement → Configure Matrix and set Matrix Being Configured to your matrix.
Then choose Service Tools → Maintenance → Calibration → Trim CM Process Variables and enter
Concentration Offset.
5. Take another concentration reading from the meter, and compare it to the laboratory value.
• If the two values are acceptably close, the trim is complete.
• If the two values are not acceptably close; i.e. not within the density specification of the sensor,
repeat this procedure.
Calculating the trim offset
Laboratory value
64.21 °Brix
Meter value 64.93 °Brix
64.21 − 64.93 = −0.72
Concentration offset: −0.72
13.8 Adjust concentration measurement with Trim Slope
and Trim Offset
Trim Slope and Trim Offset adjust the meter's concentration measurement to match a reference value.
Tip
You can adjust concentration measurement by applying the trim offset only, or by applying both the trim
offset and the trim slope. For most applications, the trim offset is sufficient.
Prerequisites
Ensure that the active matrix is the one that you want to trim. You can set the offset and slope separately for
each matrix on your transmitter.
You must be able to take measurements of your process fluid at two different concentrations.
You must be able to take a sample of your process fluid at each of these concentrations.
For each sample, you must be able to obtain a laboratory concentration value at line density and line
temperature.
Configuration and Use Manual Measurement support
MS-00809-0200-1600 May2024
Configuration and Use Manual 157
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