Hach ORBISPHERE 3658 Basic User Manual page 21

Membrane replacement
After replacing a membrane, the sensor must always be recalibrated. Allow the sensor to settle for
30 minutes in measurement phase to allow measurements to stabilize, before performing the sensor
calibration.
Removing the membrane
It is recommended to leave the sensor in place in the instrument when changing the membrane. It is
not necessary to remove it.
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.
Refer to Instrument overview
To remove the membrane, follow the steps below:
A thermistor at the top of the sensor (position No 1) is used to measure the
sample temperature, and an air duct (position No 2) 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.
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 the old membrane and discard it.
Installing the membrane
To install the new membrane, follow the steps below:
on page 6.
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