Maintenance Schedule - Hach pHD sc Analog Differential pH/ORP Sensors Manuel D'utilisation

4.5 Impedance measurements
To increase the reliability of the pH measurement system, the controller
determines the impedance of the glass electrodes. This measurement is
taken every minute. During diagnostics, the pH measurement reading
will be on hold for five seconds. If an error message appears, refer to
Error list on page 19 for more details.
To enable/disable the sensor impedance measurement:
1. Push the MENU key and select Sensor Setup.
2. Select Diag/test and push ENTER.
3. Select Imped Status and push ENTER.
4. Select Enable/Disable and push ENTER.
To see both actual and reference sensor impedance readings:
1. Push the MENU key and select Sensor Setup.
2. Select Diag/test and push ENTER.
3. Select sensor signals and push ENTER.
4.6 Modbus registers
A list of Modbus registers is available for network communication. Refer
to the manufacturer's website for more information.
Section 5 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.
16 English

5.1 Maintenance schedule

The maintenance schedule shows minimum times for regular
maintenance tasks. Perform maintenance tasks more frequently for
applications that cause electrode fouling.
Maintenance task
Clean the sensor
Inspect sensor for damage
Replace salt bridge and fill
solution
Calibrate sensor
5.2 Clean the sensor
W A R N I N G
Chemical exposure hazard. Obey laboratory safety
procedures and wear all of the personal protective
equipment appropriate to the chemicals that are handled.
Refer to the current safety data sheets (MSDS/SDS) for
safety protocols.
W A R N I N G
Personal injury hazard. Removal of a sensor from a pressurized vessel
can be dangerous. Installation and removal of these sensors should be
done by individuals trained in proper high pressure and temperature
installation. Always use industry approved hardware and safety
procedures when dealing with high pressure and/or temperature fluid
transport systems.
90 days Annually
X
X
X
Set by regulatory agencies or
experience