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MODEL 140,141, and 142 sensors CALIBRATION
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CALIBRATION
Model 140 sensors are not calibrated at the factory. The cell constant on the label is a nominal value only. The true
cell constant can differ from the nominal value by as much as ±5%. For improved accuracy, calibrate the sensor
using either a solution of known conductivity or a referee meter and sensor. If using a standard solution, choose
one having conductivity in the recommended operating range for the sensor cell constant. Refer to the analyzer
manual or product data sheet and use the range recommended for Model 400 series sensors. For the 0.2/cm cell
constant Model 140 sensor, use the range for the 0.1/cm Model 400 sensor and multiply the upper and lower limits
by two.
Do not use standard solutions having conductivity less than about 100 uS/cm for calibration. They are susceptible
to contamination by atmospheric carbon dioxide, which can alter the conductivity by a variable amount as great as
1.2 uS/cm (at 25°C). Because 0.01/cm sensors must be calibrated in low conductivity solutions, they are best cal-
ibrated against a referee meter and sensor in a closed system.
For more information about calibrating contacting conductivity sensors, refer to application sheet ADS 43-024,
available on the Rosemount Analytical website.