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Vapodest 45s
9 Trouble shooting
The chemicals used are contaminated with nitrogen
compounds.
Strong reaction in the digestion tube, caustic soda
drops got into the receiver.
Part of the glass condenser is broken, drops of the
caustic soda got into the receiver.
Tubes are contaminated with nitrogen
Carry over of ammonia from the previous sample
Check the chemicals one after the other, get a blank
value, a replacement of the chemicals might be re-
commended.
Increase the amount of water.
Exchange the glass condenser.
Clean the tubes without detergent or rinsing agent.
Extent the distillation time or check whether sufficient
alkali was added.
9.3. Results too high
Reason for error
Actions to be taken
Distillation has not been complete or distillation time
has been too short.
Ammonia escapes at leaks.
Amount of caustic soda which is added is too low, no
release of ammonia.
Not enough boric acid in the receiver, escaping am-
monia is not entirely absorbed.
Tube is not immersed entirely into the boric acid re-
ceiver.
Formation of ammonia complexes which are not de-
stroyed by the caustic soda.
No quantitative carry over of the ammonia content, the
amount of the distillate should be 100ml.
- Contaminated or detective viton cone; clean or
replace.
- Check seals at the distribution head and if neces-
sary, replace it.
- Non return valve at the condenser is bonded, clean
or replace it.
- Digestion tube is damaged at the wide neck ope-
ning.
- Glass of the distribution head is leaking, replace
it!
Check the amount delivered by the NaOH pump; about
4 ml should be delivered per second.
Increase of the amount of boric acid.
Increase of the amount of acid.
This problem only occurs with catalysts containing
mercury, sodium thiosulphate solution destroys these
complexes.
9.4. Results too low or no results
Reason for error
Actions to be taken
