Hach D3433B8.99 User Manual page 14

5.1 Clean the sensor
Pre-requisite: Prepare a mild soap solution with warm water and dishwashing detergent, Borax
hand soap or a similar soap.
Examine the sensor periodically for debris and deposits. Clean the sensor when there is a buildup of
deposits or when performance has degraded.
1. Use a clean, soft cloth to remove loose debris from the end of the sensor. Rinse the sensor with
clean, warm water.
2. Soak the sensor for 2 to 3 minutes in the soap solution.
3. Use a soft bristle brush to scrub the entire measuring end of the sensor.
4. If debris remains, soak the measuring end of the sensor in a dilute acid solution such as < 5%
HCl for a maximum of 5 minutes.
5. Rinse the sensor with water and then return to the soap solution for 2 to 3 minutes.
6. Rinse the sensor with clean water.
Always calibrate the sensor after maintenance procedures are done.
Section 6 Troubleshooting
6.1 Intermittent data
During calibration, data is not sent to the datalog. Thus, the datalog can have areas where the data is
intermittent.
6.2 Test the conductivity sensor
If a calibration fails, first complete the maintenance procedures in
1. Disconnect the sensor wires.
2. Use an ohmmeter to test the resistance between the sensor wires as shown in
Note: Be sure that the ohmmeter is set to its highest range for all infinite (open circuit) resistance readings.
Measurement points
Between blue and white wires
Between red wire and sensor body
Between black wire and inner electrode
Between black and red wires
Between black and white wires
Between red and white wires
Between red and inner shield wires
Between black and inner shield wires
Between white and inner shield wires
Between outer and inner shield wires
If one or more of the measurements is incorrect, call technical support. Supply technical support with
the serial number of the sensor and the resistance values measured.
14 English
Table 3 Conductivity resistance measurements
Maintenance on page 13.
Resistance
1089–1106 ohms at 23–27 °C
Less than 5 ohms
Less than 5 ohms
Infinite (open circuit)
Infinite (open circuit)
Infinite (open circuit)
Infinite (open circuit)
Infinite (open circuit)
Infinite (open circuit)
Infinite (open circuit)
Table 3.