11 | Help with faults
Büchi Labortechnik AG
94/106
Operation Manual K-365 Kjel Line
Problem
Possible cause
Action
Measured nitrogen
content is too low
Incomplete digestion.
u
Increase digestion time.
u
Use different Kjeldahl tablet.
The H₂SO₄ volume is too low.
u
Use KjelOptimizer software
to optimize the digestion
(download available on
BUCHI website).
Kjeldahl Tablets and H₂SO₄ in
wrong ratio.
u
Correct ratio of Kjeldahl
Tablets and H₂SO₄.
u
Use KjelOptimizer software
to optimize the digestion
(download available on
BUCHI website).
Nitrogen content per sample
tube is too high.
u
Not apply more than 200 mg
Nitrogen per sample tube.
u
Use KjelOptimizer software
to optimize the digestion
(download available on
BUCHI website).
Not enough NaOH or incorrect
concentration of NaOH used
(required is 32 %)
u
Correct volume for complete
alkalization of the digested
sample.
Leakage during distillation.
u
Check connection between
condenser and splash
protector.
u
Tighten the connection.
u
If necessary, replace it.
Titrant solution
u
Check titer of titrant.
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
Incorrect weighing.
u
Use weighing boats (easy
sample transfer from
balance to sample tube).
u
Use anti-static equipment.
u
Use larger sample sizes.
