Hach ORBISPHERE 3654 Basic User Manual page 25

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.
8.3.2 Installing the membrane
To install the new membrane, follow the steps below:
The membrane mounting surface must be clean and even (on top of the sensor,
where the membrane and sensor have contact).
Replace the membrane O-ring on the sensor head with a new one.
Note: The 29039.0 Nitril O-ring can be reused if it is still in good condition. Membrane O-rings are part
of the protection cap kit.
In the maintenance kit, pick up the two part membrane mounting tool.
Install the sleeve over the sensor head (end with shoulder downwards).
Note: Once installed, a membrane cannot be reused. Avoid touching the membrane with bare fingers,
as this may affect its sensitivity.
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