HF scientific CLX Online Residual Chlorine Monitor - Manual (Page 19)

CLX (1/12) Page 14
REV 5.1
6.2 Zero (offset) Calibration Procedure
Generally this calibration is only required if readings are expected to be below 1 mg/L or
if it is required by a regulatory authority. To perform this calibration, the water supply to
the CLX must be changed to chlorine free water such as de-ionized water. This chlorine
free water must be run through the instrument for at least 5 minutes prior to using the
following procedure.
1. On the CLX, press the MODE/EXIT button once. The screen is shown below.
2. Press either the  or buttons to get the following screen.
3. Press  to enter the zero calibration screen.
4. The screen will show the current reading on the CLX. Since there is no
chlorine, the only reading may be a slight offset due to the absorbance of the
reagents. There should be no pink color developed.
5. Press  to perform a Zero calibration. When the calibration has completed the
instrument will return to AUTO measurement mode automatically.
There is a limit of ±0.20 mg/L total adjustment available. A ZERO Cal.
greater than this will cause a CAL warning and no calibration will have
occurred. Enter SERVICE mode to clear this error.
6.3 Restore Factory Settings
If the CLX displays a CAL error or the calibration was incorrectly performed, it may be desired to
restore the factory calibration. All factory defaults including factory configurations can be reset
by holding down the  button and then pressing and releasing the  button then releasing the 
button.