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Prerequisites
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.
Procedure
1. Collect data for Comparison 1.
a. Take a concentration reading from the meter and record line density and line
temperature.
b. Take a sample of the process fluid at the current concentration.
c. Obtain a laboratory value for concentration at line density and line temperature,
in the units used by the meter.
2. Collect data for Comparison 2.
a. Change the concentration of your process fluid.
b. Take a concentration reading from the meter and record line density and line
temperature.
c. Take a sample of the process fluid at the current concentration.
d. Obtain a laboratory value for concentration at line density and line temperature,
in the units used by the meter.
3. Populate the following equation with values from each comparison.
Concentration
Lab
=
(
A × Concentration
Meter
)
+ B
4. Solve for A (slope).
5. Solve for B (offset), using the calculated slope and one set of values.
6. Enter the results as the trim slope and the trim offset.
• Using the display: Not available
• Using ProLink III: Device Tools > Configuration > Process Measurement > Concentration
Measurement
• Using the Field Communicator: Configure > Manual Setup > Measurements > Optional
Setup > Concentration Measurement > Trim CM Process Variables
7. 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, repeat this procedure.
Measurement support
Configuration and Use Manual 153