Electro-Chemical Devices (ECD) DCA-23 - Manual (Page 20)

Page 14 DCA-23 Dechlorination Analyzer
4.0 START UP
Supply sample flow to the system. Verify the sample flow is passing through both flow cells and
returning to the drain. The S10 style sensors tend to self purge air from the flow cell naturally and
usually don’t require any special treatment. Purge any trapped air in the system by loosening the
electrode fitting allowing water to overflow out of the Tee Flowcell.
Allow the system to run at least 1 hour before proceeding to the Chlorine/TRO Sensor calibration.
4.1 CALIBRATION
The DCA-23 was calibrated before shipping and should not require calibration at Start Up. If Calibration
is required calibrate the Temperature Sensor first then the pHS10 Sensor and finally the TRO Sensor.
4.2 TEMPERATURE SENSOR
Allow the sensor to equilibrate for at least 10 minutes. Verify the displayed temperature agrees with the
thermometer. If not, then adjust the temperature in the Temperature Trim °C/°F menu (see section
3.3.3 above) to agree with the thermometer. This calibration was performed in the factory calibration
but it is advisable to perform a temperature check every 2-3 months.
4.3 pH SENSOR
The PHS10 pH sensor was calibrated with pH 7.0 and pH 10.0 buffers at the factory before shipping.
Verify the displayed pH agrees with the actual pH. If the pH value deviates by more than 0.2 pH then
adjust the value in the pH Cal 1 Menu by setting the existing pH 7 value to the actual sample value and
then accepting the calibration. (See section 3.3.1 above)
4.3.1 Two Point Calibration
Remove the PHS10 pH sensor from the flow cell and place it in a beaker of pH 7.00 Calibration Buffer.
Scroll down to the pH Calibration 1 Menu and enter the menu by pressing both horizontal CALIBRATE
keys, Enter the Cal 1 line and adjust the calibration value to pH 7.00. When the mV value has stabilized
accept the value by pressing the down MENU key. An Acceptable mV value is ± 60 mV zero point offset.
Rinse the sensor and place it in a beaker of pH 10.0 Calibration buffer for the second point calibration.
Scroll down and enter the Cal2 Line. Enter the value of the Calibration Solution and accept the
calibration when the mV/pH value has stabilized. An Acceptable value is > 54 mV/pH. Rinse the sensor
and return it to the DCA-23 flow cell. (See section 3.3.1 above)
4.4 CHLORINE SENSOR (TRO)
Chlorine Calibration
Using an approved method, the DPD test for an example, verify the displayed chlorine concentration
agrees with the actual value. If further calibration is necessary, first verify the displayed temperature
and pH values are correct before beginning the chlorine standardizing procedure.
Perform a DPD test on the sample. Then using the TRO/pH/Chlorine Calibration Curve determine the
proper TRO mV value for the tested DPD Chlorine and pH values. Enter the TRO mV value in the TRO Cal
1 Screen as described in section 3.3.2 above. The DCA-23 will now display the Chlorine value associated
with that TRO value.