Hanna Instruments HI 904 - Manual (Page 106)

8-4
MAINTENANCE, PERIPHERALS
If these signs are observed, the electrode pins may be dirty. Rinse the electrode with a
solvent that is appropriate for the type of sample used – methanol is usually sufficient.
Remove debris by gently wiping with a clean cloth or tissue. Allow the probe to dry
completely before re-installing.
If a more thorough cleaning is required, soak the electrode in HI 7061 Electrode
Cleaning Solution for General Use, for several hours then rinse with water followed by
methanol. Allow to dry before re-installing.
After allowing the probe to dry, inspect the glass for cracks, especially near the electrode
pins. Replace the electrode if any cracks are found.
Note: Cleaning the detector electrode with cleaning agents will remove platinum-iodine
complexes that have formed on the electrode surface. This will lower the resistance of the
detector and therefore lower the detector’s mV readings. To counteract this change, lower the
endpoint mV value, or raise the imposed current under Method Options. The platinum-iodine
complex will reform after several titrations.
Warning: Take care to protect the electrode pins from damage! Avoid using brushes/
abrasives to clean the pins. Pins can easily bend, which will cause permanent
errors in mV readings!
8.3 Reagent Adapter Holder Maintenance
The glass tube of the reagent adapter holder can be removed for cleaning if reagent and/or
waste has dripped into it. To clean the glass tube:
1. Remove the Reagent Exchange Adapter from the top of the holder.
2. Slowly remove the glass tube. Use caution as hazardous reagent/waste may have
accumulated inside the tube.
3. Rinse the tube with dry methanol. If needed, use soap and water, then rinse with
methanol.
4. Wipe joint grease off of the ground-glass joints with a clean, dry cloth or tissue.
5. Dry the tube in a drying oven, or thoroughly wipe dry.
8.4 Reagent Exchange Adapter Maintenance
The Reagent Exchange Adapter should be cleaned if excessive liquid and/or salts have built
on the surfaces. Clean the adapter and holder if salts can be seen in or near the ground-glass
joint. To clean the adapter:
1. Loosen the caps and remove the tubes from the adapter. Make sure that the bottled
end of the tubes are not immersed in liquid to avoid spillage.
2. Remove the Reagent Exchange Adapter from the top of the holder.
3. Disconnect the caps from their threads.
4. Rinse the adapter, o-rings, and caps (if necessary) with dry methanol. If needed,
use soap and water, then rinse with methanol.