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< 7. Calibration >
7-3
IM 12F5A1-01E
7.2.2 Method of Zero Calibration using Chlorine-free Water
The method of performing Zero Calibration using Chlorine-free Water is as follows:
Note that the electrode mechanism block should be secured to the measuring tank, and the
electrodes rotating.
(1) Prepare 2-3 liters of chlorine-free water.
The chlorine-free water should consist of pure water to which 10 ml of pH 7 buffer solution and
50 mg of NaCl has been added.
(2) Select <CAL> mode (“ZERO” displayed in message display.)
Note: If Service Level code 08 is set to “1” for “initialize electrode sensitivity”, then placing the unit in <CAL> mode results in
“NO.CHNG” or “CHANGE” being displayed. In response (see Sec. 7.3) press the
YES
key and “ZERO” is displayed.
(3) Connect piping to supply chlorine-free water to the FC400G.
Close the needle valve at the sample water inlet of the FC400G, and remove the sample
water piping from the joint to the measuring tank. Release any sample water remaining in the
measuring tank by opening the drain cock on the tank. Use tubing and hardware to connect the
chlorine-free water tank to the sample water inlet. Use a head difference or a pump to supply
chlorine-free water at a flow rate of at least 100 ml/min.
(4) With the chlorine-free water flowing at the specified flow rate, watch the data display and wait for
it to stabilize.
(5) Perform zero calibration
Check that the data displayed on the data display has stabilized, then press the
YES
key.
While calibration is being performed, a blinking “mg/l” or “ppm” is displayed. When calibration
ends normally, “ZR.END” is displayed.
Note: During calibration, if an abnormality occurs then “END.E6” or “END.E7” are displayed. Refer to Sec. 7.4 for a description
of how to fix the problem.
(6) Exiting Zero calibration
Confirm that a normal “ZR.END” rather than an error message then press the
YES
key.
Pressing the
YES
key switches the display to “SPAN”. After stopping the indicator electrode,
revert the electrode to its position in the measuring tank. After fixing the electrode mechanism
block to the measuring tank, restart electrode rotation. Perform span calibration (see Sec. 7.3)
after performing zero calibration.
7.2.3 Auto Zero Calibration using Chlorine-free (chlorine not included) Water.
Auto Zero Calibration is performed using an activated charcoal filter. Setup as follows:
(1) In Service Level code 09 [Washing / Auto zero calibration] set “1” for Auto zero calibration.
The default is “0” for washing.
(2) Select “*AZ.CAL” for Auto zero calibration sequence in Setting Level.
After selecting “Auto Zero Calibration timer ON (*T. ON), select Calibration Interval (*INT D),
Calibration Setup time (WT.min), and Stabilization (settling) time (*RT.min).
Default values are : For Calibration Interval (*INT D), 10 days (refer to zero filter flushing
functions); for Calibration Setup time (WT. min), 10 min ., for Stabilization (settling) time (*RT.
min), 10 min.
When Auto Zero Calibration starts, the analog output is held, <HOLD> lights, and <CAL> (blinking) is
displayed. At the same time, the <MAINT> contact output turns ON.
After the calibration setup time has elapsed, the measured value drops to near zero, and after this
measured value has stabilized it is automatically reset to zero. The method used to determine if the
value has stabilized is the same as for manual calibration.
When calibration is completed, the flow through the unit is switched from zero water (pure deionized
water) to sample water, then after the stabilization (settling) time has elapsed the analog output hold is
released, <HOLD> and <CAL> go OFF, and the <MAINT> contact turns OFF.