Maintenance Schedule - Hach pH Manuel D'utilisation

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.
Chemical exposure hazard. Dispose of chemicals and wastes in accordance with local, regional and
national regulations.

5.1 Maintenance schedule

Table 1 shows the recommended schedule of maintenance tasks. Facility requirements and
operating conditions may increase the frequency of some tasks.
Task
Clean the sensor on page 18
Replace the salt bridge
on page 18
Calibrate the sensor
5.2 Clean the sensor
Pre-requisite: Prepare a mild soap solution with a non-abrasive dishwashing detergent that does not
contain lanolin. Lanolin leaves a film on the electrode surface that can degrade the sensor
performance.
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.
Note: Sensors with antimony electrodes for HF applications may require additional cleaning. Contact technical
support.
Always calibrate the sensor after maintenance procedures are done.
5.3 Replace the salt bridge
Replace the salt bridge and the standard cell solution at 1 year intervals or when calibration fails after
the sensor has been cleaned.
6
Frequency is dependent on the operating conditions.
18 English
W A R N I N G
C A U T I O N
Table 1 Maintenance schedule
1 year
X
Set by regulatory agencies or experience
As necessary
6
X