Modbus Registers; Clean The Sensor; Test The Conductivity Sensor - Hach 3400 Serie Manual Del Usuario

Modbus registers

A list of Modbus registers is available for network communication. Refer
to www.hach.com or www.hach-lange.com for more information.
Maintenance
W A R N I N G
Personal injury hazard. Only qualified personnel should conduct the tasks
described in this section of the manual.

Clean the sensor

W A R N I N G
Chemical hazard. Always wear personal safety protection in accordance with the
Material Safety Data Sheet for the chemical that is used.
W A R N I N G
Personal injury hazard. Removal of a sensor from a pressurized vessel can be
dangerous. Reduce the process pressure to below 10 psi before removal. If this is
not possible, use extreme caution. Refer to the documentation supplied with the
mounting hardware for more information.
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 a 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.
Troubleshooting
Intermittent data
During calibration, data is not sent to the datalog. Thus, the datalog can
have areas where the data is intermittent.

Test the conductivity sensor

If a calibration fails, first complete the maintenance procedures in
Maintenance on page 15.
1. Disconnect the sensor from the module.
2. Use an ohmmeter to test the resistance between the sensor wires as
shown in Table 4.
Note: Be sure that the ohmmeter is set to its highest range for all infinite (open
circuit) resistance readings.
Table 4 Conductivity resistance measurements
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.
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)
English 15