Calibration Procedure; Measurement Considerations; Troubleshooting - Extech Instruments ExStik CL200 User Manual

Calibration Procedure

For accuracy, the CL200 requires periodic calibration.
1. Using a chlorine standard, of known concentration (CL207), perform a normal sampling
procedure with 20 ml of the solution and a reagent tablet. Wait for the display icon HOLD
(approx. 2-minute sampling time).
2. With the meter still in the solution, long press the Mode/Hold button for approximately 5
seconds, until CO appears.
3. The displayed concentration value can now be adjusted to match the actual concentration of the
solution.
4. Press the MODE/HOLD key to increase the value or press the CAL/RECALL button to decrease
the value.
5. After the adjustment, short press the ON/OFF button, SA will appear, followed by END. This
confirms that the adjustment was saved.
6. Switch OFF the meter.

Measurement Considerations

1. If the meter is new, or has not been used for several weeks, at least two tests should be made
to condition the electrode.
2. Do not touch the reagent tablets. Touching can cause contamination. See the earlier section
'Reagent Tablet Health Hazards' for important safety information.
3. If the electrode has not been used for 24 hours, wipe the tip with a clean/dry towel before use.
4. Before use, wash the sample cups and the caps, rinsing them completely.
5. The CL200 should not be left in a solution while switched OFF, otherwise readings may take
longer to stabilize.
6. Do not touch the sensor surface except with a clean/dry towel.
7. When measuring solutions of varying chlorine concentrations, i.e. 0.1ppm and 5.0ppm, use
separate sample cups.
8. Discard the sample cup when it exhibits a change in color.
9. Preserve the electrode by completely wiping it dry and replacing the electrode cover
immediately after testing. The electrode should always be stored in the dry cap.
10. Cover the connector with the clear cover whenever the electrode is removed from the meter
body.
11. Gently stirring the probe in the solution for 10 seconds, within the first minute of operation, will
yield quick and accurate readings. Do not stir after 10 seconds.

Troubleshooting

1. If the unit appears locked, it is possible that the Data Hold mode has been inadvertently
accessed. If the HOLD icon is displayed, press the MODE button, or turn the meter off and
restart.
2. If the meter continues to appear locked, remove the batteries and long press the power button
for 10 seconds. Install the batteries and try again. When the batteries are removed, stored
readings are cleared.
3. If the meter displays -1, in a known level of chlorine, the meter or electrode may be defective.
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