Büchi Labortechnik AG
Help with faults | 11
Operation Manual K-365 Dist Line
93/106
Problem
Possible cause
Action
Samples do not get
dark blue/brown af-
ter addition of
NaOH
Air in NaOH hose.
u
Flush the system. See
Chapter 8.13 "Dosing
manually", page 74
No catalyst used for digestion
(only H
2
O
2
or Kjeldahl tablets
ECO).
11.2
Troubleshooting distillation
Problem
Possible cause
Action
Splashing during dis-
tillation or addition
of chemicals
The sample tube is too small.
u
Select a bigger sample tube.
Sample volume too high.
u
Lower sample volume.
Amount of water used for dilu-
tion is too low.
u
Increase dilution volume.
Measured nitrogen
content is too high
Air in titration system, burette
or tubes.
u
Tighten the connections.
u
Flush the tubing with titrant.
u
Refill burette.
Carry over during distillation.
u
Insert less sample.
u
Avoid big concentration
differences in measurement
series.
Titrant concentration too high.
u
Lower the titrant
concentration.
Error in calculation.
u
Check calculation.
u
Check titration parameters.
u
Check the titer for the
titrant in use.
pH electrode is defective.
u
Maintain electrode. See
related documentation
u
If necessary, replace it.
The glassware is dirty.
u
Clean the glassware. See
Chapter 10.2 "Cleaning and
servicing the sample tube",
page 82
