8 Troubleshooting
K-375 / K-376 / K-377
Operation Manual, Version E
146
Boiling retardation/bumping/foaming
∙ Missing digestion rods or boiling stones are used
∙ Missing Antifoam tablet or other anti-foaming agent
Typical mistakes distillation
Samples do not get dark blue/brown after addition of NaOH
∙ Empty NaOH tank
∙ Air in NaOH hose
∙ No catalyst used for digestion (only H2O2)
Splashing during distillation or addition of chemicals
∙ Choosen wrong sample tubes
∙ Volume in sample tubes too high
∙ Not enough water used for dilution
Other problems that may occur
Problem
Cause
Corrective measure
Nitrogen content too
high
∙ Air in titration system, buret,
tubes
∙ Carry over during distillation
∙ Wrong titrant
∙ Error in calculation
∙ Defective pH electrode
∙ Defective colorimetric sensor
∙ Dirty glassware
∙ Air bubbles disturb the colori-
metric titration
∙ Refill buret
∙ Use less volume, or increase
water volume for dilution
∙ Use right concentration
∙ Check calculation and
concentration of titration,
molar reaction factor, factor of
titrant
∙ Calibrate electrode, replace if
necessary
∙ Clean the sensor surface,
place the sensor in cleaning
solution during idle periods
∙ Only use clean glassware
∙ Check the top fitting on the
condensate inlet
