ATI
Q46C2 2Electode Conductivity System
Part 8
– Calibration
43
O&M Manual
Rev-H (6/19)
8.2
Performing a 1-Point Calibration
This calibration method is intended to be used as an on-line calibration method or a wet-cal with
reference solutions. During calibration, the system will display the current conductivity reading,
and the user can manually enter a reference value from a reference solution bottle or a comparative
reference instrument.
For wet calibrations, the user may use pre-made calibration references (also available from ATI) or
a NaCl solution may be made using pure, dried NaCl crystals and one liter of high purity, de-ionized,
CO
2
-free water as mixed in the table shown in Figure 7-1. All table data is at 25°C - therefore, the
sensor must be at this temperature to calibrate properly using the table data. If another reference
calibration solution is being used, be sure to note temperature of reference solution before
calibration. Since the sensor must ideally be at the specified temperature, wet calibrations can be
difficult to perform accurately.
Figure 22 - NaCl Reference Solution for Calibration
During the 1-point calibration, the User must be careful to calibrate with a solution that falls into the
measuring range selected. If the calibration solution is outside the measuring range, an error will
result.
Procedure
1.
Determine whether the calibration will be done on-line or with the sensor removed and
placed into a reference solution. If the sensor is removed from the application, rinse and
clean.
2.
If the sensor has been removed and placed into a solution, allow sensor to temperature
equilibrate with the solution as much as possible. With the sensor coming from an
application that differs greatly in temperature, the user may have to wait as much as 5
minutes. If the sensor is on-line, the user may want to set the output HOLD feature prior
to calibration to lock out any output fluctuations.
3.
Scroll to the CAL menu section using the MENU key and press ENTER or the UP arrow
key.
Cal Cond
will then be displayed.
4.
Press the ENTER key and the lower line of the display will prompt the user to
Place the
sensor in reference solution
. Press the ENTER key.
5.
The screen will display the last measured conductivity value and a message will be
displayed prompting the user for the lab value. The user must then modify the screen value
with the arrow keys and press ENTER. The system then performs the proper checks.
NaCl Reference Solution for Calibration (25°C)
μS/cm
NaCl (gm)
NaCl (mg/L)
100
0.05
50
200
0.10
100
