Calibration; Calibration By Direct Input Of The Cell Constants (Autcal Off) - ProMinent Portamess 911 Conductivity Operating Manual

Calibration

6 Calibration
User qualification: instructed user
n
Calibration adapts the Portamess 911 Conductivity to the cell constant of the sensor. In general, it is
enough to enter the cell constants specified by the manufacturer of the sensor into the unit.
Tab. 2: General calibration information
Parameter
Calibration solu‐
tions
Clean sensor
Cell constant
4-pin sensors
Sensor LF 204
16
Ä Chapter 2.2 'User qualification' on page 8
Explanation
Solutions for the calibration of conductivity measuring units are unbuffered
systems. Their conductivity values are not stable and are affected by low
contamination or dilution, e.g. drops of water adhering to the sensor.
Ensure that the sensor is clean before calibration. Use distilled water to
rinse out any residue. After this, we recommend drying the sensor and
rinsing it with the intended calibration solution.
The cell constant is determined by the size and geometric arrangement of
the sensor. The cell constant is the core size of conductivity sensors. The
cell constant is virtually immutable. Clean sensor surfaces without insulating
coatings are a prerequisite for this. Regular calibration is therefore not gen‐
erally necessary
With 4-pin sensors, the principle of separate current/voltage electrodes
means that the partial contamination of the sensor does not lead to meas‐
uring errors in practice. By contrast, sensors fully contaminated with insu‐
lating coatings cause the measurement to fail.
The cell constant is given with a tolerance of 1.5 % for the conductivity
sensor LF 204. In calibration mode (AutCAL OFF), this cell constant is
entered into the Portamess 911 Conductivity and saved. Further calibration
with calibration solutions is not required.
6.1 Calibration by direct input of
the cell constants (AutCAL
OFF)
1. INFORMATION: Sensor LF 204: C =
0.475 cm -1
[CAL] to access calibration. The cell
Use
constant determined and/or set during
the last calibration is displayed.
lets you exit calibration again.
'meas'