BUCHI Distillation Unit K-355 - Manual (Page 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