
Calibration and Maintenance
9
Instruction Manual
Calibration and Maintenance
LIQ-MAN-400
May 2017
3.1
Calibrating the sensor
Rosemount 400/400VP Contacting Conductivity Sensors are calibrated at the factory and do not
need calibration when first placed in service. Simply enter the cell constant printed on the label into
the transmitter. After a period of service, the sensor may require calibration. For more
information on calibration, refer to
Application Data Sheet
.
3.1.1
Calibrating using a standard solution
If using a standard solution, choose one having conductivity in the recommended operating range
for the sensor cell constant.
1.
Immerse the rinsed sensor in the standard solution and adjust the transmitter reading to
match the conductivity of the standard.
2.
For an accurate calibration:
a. Choose a calibration standard near the midpoint of the recommended conductivity
range for the sensor.
b. Do not use calibration standards having conductivity less than 100 µS/cm.
c. Turn off automatic temperature compensation in the transmitter.
d. Use a standard for which the conductivity as a function of temperature is known.
e. Use a good quality calibrated thermometer with an error rate less than ±0.1 °C to
measure the temperature of the standard.
f. Follow good laboratory practice. Rinse the beaker and sensor at least twice with
standard. Be sure the rinse solution reaches between the inner and outer electrodes by
tapping and swirling the sensor while it is immersed in the standard.
g. Be sure air bubbles are not trapped between the electrodes. Place the sensor in the
standard and tap and swirl to release bubbles. Note the reading and repeat. If readings
agree, no trapped bubbles are present. Repeat until two subsequent readings agree.
Section 3: Calibration and maintenance