Hach ORBISPHERE 31xxx Manuel D'utilisation Simplifié page 12

The membrane needs to be replaced once or twice a year depending on application conditions. This
can be tailored accordingly.
Note: If you are not familiar with ORBISPHERE sensor servicing, your Hach representative will be glad to assist
you
6.2 Testing the sensor condition
Periodically, inspect visually the sensor head for any deposits. Rinse it under clean tap water, and
dry with a clean tissue.
To verify the sensor, check measurements against a known standard sample value:
• If reading deviation is ±1% of the expected value, no action needs to be taken.
• If deviation exceeds ± 1%, perform a new calibration.
• If deviation exceeds 10% of the original values, replace the membrane.
Carry out the 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.
6.3 Membrane replacement
6.3.1 Removing the membrane
1.
1. Place the thermal conductivity sensor vertical with the head up. Remove the plastic storage cap.
2. Unscrew the protection cap, using the tool provided in the maintenance kit.
Never remove the protection cap, unless you plan to replace the membrane.
3. Pay attention to the components inside the protection cap. Note the assembly order of each item.
4. Pull up the membrane holding ring with the tool provided in the maintenance kit. The membrane
holding ring comes in two slightly different internal diameters, depending on the membrane(s)
total thickness. Remove membrane(s).
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