Hach Ultra ORBISPHERE 3658, Operator'S Quick Manual

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Page 12
Sensor maintenance includes membrane
replacement and external cleaning to restore the
original sensor sensitivity. This means low
running costs and down time reduced to a
minimum.
The membrane needs to be replaced once or
twice a year depending on application conditions.
This can be tailored accordingly.
Periodically, visually inspect the sensor head for
any deposits. Rinse it under clean tap water, and
dry with a clean tissue. To verify if the membrane needs to be replaced,
check sensor measurements against a known
standard sample value. If the deviation exceeds
10% of the original value, replace the membrane.
CAUTION
Carry out any maintenance in a clean dry place in
order to avoid damaging the sensor's precision
components, and also to prevent water or
humidity from getting into the sensor.
Sensor Maintenance
It is recommended to leave the sensor in place in the instrument when changing the membrane.
To remove the membrane, follow the steps below:
To avoid any liquid coming into contact with the TC sensor chip via the purge path, check that
the flow chamber is completely empty of any liquid sample.
Then remove the flow chamber from the sensor by turning the flow chamber locking nut counter-
clockwise and gently lifting it off the sensor.
CAUTION
A thermistor at the top of the sensor (position No 1 in the
illustration) is used to measure the sample temperature, and
an air duct (position No 2 in the illustration) is used for the
purge gas inlet. Do not bend or damage either of these
components by trying to twist the flow chamber off the sensor.
Unscrew the protection cap, using the tool provided in the
maintenance kit.
CAUTION
Never remove the protection cap, unless you plan to replace
the membrane.
Pull up the membrane holding ring with the tool provided in the
maintenance kit.
Remove membrane.