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Cleaning procedures
5.1.3
Step 3 (if necessary): Scarfing
Scarf the sample vessel with the flame of a Bunsen burner.
When scarfing use crucible tongs and wear fire-proof gloves.
Allow the glass to cool on a heat-resistant sheet before using it again.
Risk of injury due to shattering glass
If the glass should shatter, slivers of glass may cause injury.
WARNING
Scarf the glass slowly and evenly. Do not allow it to glow red-hot.
Allow the glass to cool before rinsing with water.
Wear sound laboratory clothing and safety goggles.
5.1.4
Step 4 (if necessary): Cleaning with oxidising acid
Only in the case of contamination which has not been removed using the previous
measures: Clean the glass with a concentrated oxidising acid.
This work must only be carried out by persons who are familiar with the dangers
involved when handling acids and who are familiar with the necessary safety
procedures. Acquaint yourself with the properties of the substances used. Pay
attention to the appropriate R and S phrases (safety advice).
5.2
Cleaning the ring and plate
Before using a ring or plate for the first time and before each measurement the
measuring probes must be thoroughly cleaned. The cleanness of the measuring
probes cannot be assessed visually.
If the ring or plate is only to be used in an aqueous system then rinsing it under
flowing and then under distilled water is sufficient.
After previous contact with organic liquids the measuring probes must first be
rinsed with a solvent (e.g. acetone) and then with distilled water.
page 33
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