Metrohm 807 Dosing Unit - Manual (Page 39)

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4 Handling and maintenance
807 Dosing Unit
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4 Handling and maintenance
4.1 Care and upkeep
In contrast to the Dosino drive, dosing units require regular care.
If aggressive reagents are dosed with dosing units, then such units should
be rinsed with an inert solvent when not in use ( 'PREP/Preparing func-
tion) and then subsequently emptied ( 'EMPTY/Emptying function). In
the event of that the dosing unit is not in use for
> 2 days, the dosing unit
should be emptied without fail, because even water can corrode the buret
glass in the event of prolonged periods of disuse. Remove the dosing drive
in the event of prolonged periods of disuse (longer than one week).
NOTE
Dosing units require regular inspections and must be disassembled
down to the cylinder unit from time to time and cleaned as necessary.
WARNING
Monthly or even weekly inspections are called for in the event that
alkali, corrosive or high-concentration reagents are used. If non-prob-
lematic reagents are used, then the inspection intervals can be exten-
ded to between six and twelve months.
4.1.1 Cleaning dosing cylinder and dosing piston
CAUTION
Never disconnect the cylinder from the cylinder base. Neither the cylin-
der nor the piston should ever be placed in a dishwasher!
￭ Check the leak-tightness of the dosing piston and cylinder. Inspect the
dosing piston for deformations or damage to the sealing lips. The pis-
ton and the cylinder must be replaced in the event that any changes
are discovered.
￭ Degreasing the piston and the glass cylinder are part of the cleaning
procedure. Use a cloth to wipe down the piston.