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Reference Manual
00809-0100-3222
4
Calibration
4.1
Sensor calibration
The nominal cell constant of the 1 in. diameter sensor is 6/cm and the nominal cell
constant of the 2 in. diameter sensor is 4/cm. The error in the cell constant is about ±10%,
so conductivity readings made using the nominal cell constant will have an error of at least
±10%.
For higher accuracy the sensor must be calibrated. The sensor can be calibrated using a
standard solution or a previously calibrated sensor and transmitter. Calibration against a
standard solution requires that the sensor and outer flanges be removed from the process
piping. Generally it is a useful method only when the sensor is first installed. Otherwise,
the sensor should be calibrated in place against a referee sensor and transmitter.
To calibrate against a standard solution, screw a short length of metal pipe into one of the
outer flanges and cap the open end of the pipe. Stand the sensor on the capped end and
fill it with standard to the level of the upper surface of the second outer flange. Be sure the
shorting strap is connected to both flanges.
Adjust the analyzer reading to match the known conductivity of the standard. Do not
place a temperature sensor or any object inside the conductivity sensor during calibration.
Doing so will alter the measured conductivity and introduce an error in the measurement.
Once the sensor has been installed in the process piping, removing it for calibration is
impractical. In this case, calibrate the sensor against a referee sensor and transmitter,
ideally while both sensors are simultaneously measuring the same process liquid. If this is
not practical, calibrate the sensor against the results of a measurement made on a grab
sample.
For more detailed information on calibration methods, please reference application data
sheet ADS-43-025 available on the
Rosemount 222 Sensors
Emerson Liquid Analysis website
Calibration
September 2018
19
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