Watts HF scientific 28030, Owner'S Manual

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CLX-XT (28652) Page 18
REV 5 (5/2020)
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-XT 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-XT, 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-XT. 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-XT displays a CAL error or the calibration was incorrectly performed, it may
be preferred to restore the factory calibration. All factory defaults settings including the
factory calibration can be reset by holding down the

button and then pressing and
releasing the

button then releasing the

button.