Instruction Manual Section 10: Calibration
LIQ-MAN-56 April 2017
Calibration 79
10.6 Calibration —Chlorine
W
ith a Chlorine measurement board and the appropriate sensor, the 56 can measure any of
four variants of Chlorine:
• Free Chlorine
• Total Chlorine
• Monochloramine
• pH-independent Free Chlorine
The section describes how to calibrate any compatible amperometric chlorine sensor. The follow-
ing calibration routines are covered in the family of supported Chlorine sensors:
• Air Cal
• Zero Cal
• In Process Cal
10.6.1 Calibration — Free Chlorine
A free chlorine sensor generates a current directly proportional to the concentration of free
chlorine in the sample. Calibrating the sensor requires exposing it to a solution containing no
chlorine (zero standard) and to a solution containing a known amount of chlorine (full-scale
standard). The zero calibration is necessary because chlorine sensors, even when no chlorine
is in the sample, generate a small current called the residual current. The analyzer
compensates for the residual current by subtracting it from the measured current before
converting the result to a chlorine value. New sensors require zeroing before being placed in
service, and sensors should be zeroed whenever the electrolyte solution is replaced.
To calibrate the chlorine sensor, access the Calibration screen by pressing ENTER/MENU
from the main screen, select S1 or S2 Measurement and press ENTER/MENU. Press INFO at
any time to learn more about this procedure. A yellow screen will appear with detailed
instructions and information.
The following calibration routines are
covered:
1. Zero Cal Zeroing the sensor in
solution with zero free chlorine
2. Grab Cal Standardizing to a
sample of known free chlorine
concentration
1. To Zero Calibrate the analyzer with
the sensor attached, follow the step-
by-step procedures displayed on-
screen.
2. To perform a Grab Calibration by
Standardizing the sensor, follow the
step-by-step procedures displayed
on-screen.
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