Aquaprobe
®
AP-700, AP-800 & AP-2000 Instruction Manual
10401-00870 Rev R
If a problem occurs during calibration, an error message will be displayed. Refer to
Calibration Error Messages
in section 10.4 for error message handling.
14.10. Replacing the Optical DO Cap
The Optical DO Cap contains a lens, which is coated with an oxygen sensitive
luminophore, which is in turn coated with a black rubber compound that provides optical
isolation but is permeable to oxygen. Oxygen molecules pass through the rubber into the
luminophore.
Never touch the black rubber end of the DO electrode as the oils in your
skin can block the pores in the rubber coating and stop it from working correctly.
The luminophore within the DO Cap will need replacing every few years, as it is a
consumable item. Since the luminophore is an integral part of the DO Cap, the entire DO
Cap is replaced. An Optical DO Cap can last up to ten years dependent upon the amount
of use it gets.
Caution: The inside of the Optical DO Cap is very sensitive to light and can be ruined
(bleached) if it is exposed to bright light for any length of time.
Never remove the Optical
DO Cap from the Probe unless you intend to replace it with a new one.
When replacing an
Optical DO Cap, do so under subdued light.
To replace the Optical DO Cap, follow these simple steps.
1. Remove the Probe sleeve.
2. Unscrew the Optical DO Cap from the end of the DO/EC electrode by rotating it anti-
clockwise.
Do not touch the exposed optical components.
3. Apply a light smear of silicone grease to the thread and O ring.
4. Remove the new Optical DO Cap from its light-proof bag and quickly screw it onto
the end of the DO/EC electrode. Ensure that the cap is screwed fully onto the
electrode and that it is done up tight.
5. Carry out both Zero point and 100% point DO calibration as described earlier.
Please Note: It is essential when replacing the Optical DO Cap to calibrate the Zero
point BEFORE calibrating the 100% point.
© 2017 Aquaread
®
Ltd.
www.aquaread.com
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