Operating instructions

84 METTLER TOLEDO DE40/50/51 Density Meter
17. Maintenance
17.1 Changing internal battery
The battery is used for data storage and has a service life of around 5 years when it is kept
charged. We thus recommend switching the instrument on now and then to ensure the
battery remains operational during this time.
17.2 Power line voltage, power line, fuse
The DE40/50/51 will adapt automatically to the power line voltage in the range of 100 to
240V and 50/60 Hz.
Changing blown fuses:
- Switch off the instrument and disconnect all cables on the rear of the instrument.
- Put the instrument on the rear side.
- Remove the small plate at the instrument’s bottom plate by unscrewing the 2 screws.
- Change the blown fuse(s) and put the small plate in place again. Make sure to use the correct
fuse type for replacement: T3.15A / 250V.
17.3 Replacing the silicagel
- Replace the silicagel of the drying tube when it becomes pink. If this is not done the drying
of the measurement tube (and thus the adjustment with dry air) is no longer assured.
17.4 Replacing the tube nozzles
If you find air bubbles in the measurement tube on every sample injection which do not
originate from the sample itself, the tube nozzle may be leaking or damaged. To change the
tube nozzles, proceed as follows:
- Carefully remove the protective silicone cap that holds the nozzles correctly in place. Make
sure not to tear at the rim, but hold its strong middle part with your fingers.
- Unscrew the tube nozzle anticlockwise and then screw in the new one tightly by hand. Do
not apply pressure as this would damage the measurement tube.
- Then put the protective silicone cap in place again with the squared hole at the bottom so
that leaking liquid from the cell unit can flow out.
Maintenance