Hach-Lange NH4D sc Ammonium Sensor - Manual (Page 29)

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Section 5 Maintenance
Important Note: Only qualified personnel should conduct the tasks
described in this section of the manual.
5.2 Clean the sensor
Important Note:
Do not touch the membranes with fingers.
Do not clean the sensor cartridge with sharp objects that may
cause scratches and do not use any chemical cleaning agent.
1. Clean the sensor cartridge with the soft brush supplied.
2. Clean the sensor body (not the cartridge) with a sponge or
brush.
3. Rinse the sensor with clean, lukewarm tap water.
Note: Do not use destilled water.
5.3 Replace the sensor cartridge
The sensor cartridge is replaced as described below and in
Figure 12 on page 30 .
1. Clean the sensor and thoroughly dry the sensor cartridge and
the sensor adapter.
2. Unscrew the locking ring and remove.
Important Note: The sensor cartridge must direct downwards so
that no water can run into the sensor adapter. The contacts
between the sensor and the sensor cartridge must remain dry.
3. Pull the sensor cartridge out of the sensor adapter and dispose
of the old sensor cartridge and opaque gasket per applicable
regulations.
4. Ensure that the new opaque gasket is installed during every
sensor cartridge replacement.
5.1 Maintenance schedule
Maintenance task 30 days 1 12 months
Clean sensor 2 x
Replace the sensor cartridge 3, 4 x
Check sensor for damage x
Check measured value by lab reference analysis and correct values by matrix
correction if required
3
x
1 Recommendation: weekly during the first month in operation
2 The frequency of cleaning depends on the application. In some applications more or less frequent cleaning may be necessary.
3 In typical operating conditions, a different interval may be required depending on the specific application and local conditions.
4 Sensor cartridges are wear parts and are not covered by the instrument warranty.
Important Note: Do not check the sensor with usual NH
4
–N standard solutions, because the ion strength of
normal standard solutions are not strong enough. Use therefore calibration solutions with artificial ion matrix
generate to have plausible measurements (e.g. LCW892).