HF scientific CLX Online Residual Chlorine Monitor (Old) - Manual (Page 20)

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 S or Tbuttons 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, this is a zero offset.
5. Press  to Zero the instrument and return to AUTO measurement mode.
Note: 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 S button and then pressing and releasing
the 
button then releasing the S button.
CLX (9/07) Page 14
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