YOKOGAWA RC400G, User Manual

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<7. Calibration>
7-3
IM 12F4A1-01E
7.2.3 Automatic Zero Calibration Using Chlorine-Free Water
Automatic zero calibration is performed using an activated charcoal filter. The parameters should
be set in following the procedure.
(1) Select “execution (on)” in function code “5.”, “Automatic zero calibration function” in
<PROGRAM.1>. The default setting is “stop (oFF).”
(2) Set the automatic zero calibration sequence parameters in “A,” “b” and “c” in
<PROGRAM.2>. Function code “A” is “Setting automatic zero calibration cycle,” function
code “b” is “Setting automatic zero calibration preparation time” and function code “c” is
“Setting automatic zero calibration relaxation time.” The default settings are: “10 days (note:
refer to zero filter flushing function)” for function code “A”, “10 minutes” for function code “b”
and “10 minutes” for function code “c”.
Once automatic zero calibration starts, the analog output is held, <HOLD> lamp turns on, and
<CAL> lamp flashes. At the same time, the solenoid valve SV6 is energized to let chlorine-free
water flow and the analyzer waits a preset calibration preparation time. When the analyzer
reads a value approximate to zero and confirms that the reading has stabilized, it performs zero
calibration. The analyzer checks the stability using the same criteria of manual calibration. After
the calibration is completed, the solenoid valve SV6 is de-energized to let sample water flow and
the analyzer waits a preset relaxation time, the time required for zero water to be replaced with
sample water. The held analog output is released, and <HOLD> and <CAL> lamps turn off.
NOTE
• The automatic calibration will be aborted if the mode is changed to the one other than the
<MEAS.> mode during the calibration. Upon abort, the held analog output is released, and
<HOLD> and <CAL> lamps turn off. The calibration cycle timer is reset.
• The [FUNC] key is valid even during automatic calibration. ([FUNC] key does not affect the
automatic zero calibration sequence.)
• The calibration cycle timer will start at zero when:
* the automatic zero calibration is set to “on” upon startup;
* the setting of automatic zero calibration is changed to “on”;
* the automatic calibration cycle is changed (only when automatic zero calibration is
enabled).
• The timer continues to count regardless of operation mode.
• Automatic zero calibration is executed only when the analyzer is in <MEAS.> mode. If
the time for automatic zero calibration comes while the analyzer is in other modes, the
calibration will be cancelled. The internal timer is reset and then starts counting.
• If the time for automatic cleaning comes during automatic zero calibration, the automatic
cleaning will be cancelled. If the time for automatic zero calibration comes during automatic
cleaning, the automatic cleaning is aborted and the automatic zero calibration starts. In this
case, the sequence for switching the solenoid valves SV3 and SV4 continues, but this does
not affect the automatic zero calibration.
14th Edition : Jul. 15, 2020