Buchi Distillation Unit K-355 Manual de usuario descargar pdf (Pagina 24)

6 Operation

24 K-355 Operation Manual, Version G

6.5 Steam generator status

6.5.1 Heating

A constant colon (:) and an “H” in the STEAM-display indicates, that the steam generator is heating.

A ﬂashing colon (:) and a signal sound for 1 second indicates that the steam generator is ready.

6.5.2 Standby mode (after 30 minutes)

The TIME display and STEAM display show (-----).

Press “START” to cancel the standby mode.

6.6 Switching ON/OFF checklist

To switch on and preheat the instrument, proceed as follows:

Check the ﬁlling level of the supply tanks.•

Open the main water tap.•

Switch on the instrument and wait until the steam generator is ready.•

Insert an empty sample tube and an empty receiving vessel.•

Close the protective door.•

Set the distillation time to 2 minutes (see section “Setting the distillation time”) and the steam to •

100% (see section “Setting the steam power”).

Start the distillation by pressing “START”.•

To switch off the instrument, proceed as follows:

Switch off the instrument.•

Close the main water tap.•

Rinse the reagent 1 pump with distilled water when it is used for the additon of strong acids.•

6.7 Carrying out a distillation

To carry out a distillation, proceed as follows:

Switch on the instrument and wait until the steam generator is ready.•

Insert the sample tube containing the sample.•

Prepare a conical ﬂask or a similar receptacle with a volume of about 250 ml as receiving vessel.•

If required, select suitable chemicals in accordance with the method and the substance you deter-•

mine.

Add reagents as required.•

Set the required distillation time or select a program.•

Start the distillation by pressing “START”.•

For Kjeldahl distillation note the following:

Fill boric acid solution of 4% and 2-3 drops of Sher indicator into the receiving vessel. Alternative: •

Select suitable chemicals for the back titration.

Add water to dilute the sample by pressing “REAGENT 1”. The dilution with water prevents a too •

violent reaction when the sodium hydroxide solution is subsequently added. The sample must be

diluted in a ratio of approximately 1 part of acid to 2 parts of water.

Add sodium hydroxide solution by pressing “REAGENT 2”: Recommended alkali concentration: •

32%. Add alkali to the sample in a ratio of about 1 part of acid to 3 parts of sodium hydroxide

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Buchi Distillation Unit K-355 Manual de usuario Pagina 24