Section 4
Maintenance
4.1 General
The Model 3505 is designed to give optimum performance with minimum maintenance. It is only
necessary to keep the external surfaces clean and free from dust. To give added protection when
not in use the unit should be switched off and covered with the optional dust cover (060 406).
4.2 Cleaning/Re-conditioning of Combination Electrodes
For general purpose use, combination electrodes can be cleaned with a mild detergent solution or a
commercial glass cleaning solution (provided these are not strongly acidic). The electrode surface
should be wiped with a clean cloth soaked in the cleaning agent, and/or allow the membrane to
stand in the solution until clean. Rinse and repeat as necessary. Electrodes which have been
allowed to dry out should be soaked overnight in warm distilled water.
Table of Cleaning Agents for Glass Electrodes
Deposit
Cleaning Agent
General Deposits
Genklene or mild detergent solution
Inorganic coatings
Commercial glass cleaning solution (not strongly acidic)
Metal compounds
Acid solution, not stronger than 1M
Oil/Grease
Complexing agent (EDTA) or suitable solvent
Resins/Lignins
Acetone, alcohol or detergent (not strongly alkaline)
Proteins (blood, etc)
Enzyme solutions (e.g; pepsin in 0.1M HCl)
Stubborn deposits
Hydrogen peroxide, sodium hypochlorite or domestic bleach
NOTE:
Solvents such as carbon tetrachloride, trichloroethylene, petroleum,
ether, etc, MUST NOT be used for cleaning electrodes that have a plastic body
or a plastic protective skirt.
350 550/REV A/03-03
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