Hach EZ Series Basic User Manual page 35

Error/Warning message
Analysis results are unstable
E-stop/ Reinitialize the dispenser!
Sensor pH/mV error
Titration error
Result alarm
Possible cause
Micropump is defective
Peristaltic pump is defective
Valve is defective
Stirrer is defective
Dispenser is defective
The position of tubes in the analysis
vessel is not correct
The reagents have expired.
When Emergency stop is pushed,
the dispenser stops and must be
started again.
The pH or mV electrode are
defective or not connected.
The titration did not measure an EP
or the maximum amount of titration
solution was added without getting
an endpoint pH or mV.
The measured result is too high or
lower than the set values in the
results (F5 > Software > Results >
Alarm).
Solution
Make sure the reagents are dosed
correctly and there is no air in the
tubing.
Make sure that the drain and
sample pump are operating
correctly.
Make sure that the valves (sample,
REF1, REF2, clean) are operating
correctly.
Examine if there is a magnetic
stirrer bar in the analysis vessel and
if the solution is stirred during
analysis.
Make sure that the dispenser piston
is filled with liquid and that there is
no air in the tubing.
Examine the position of the tubing in
the analysis vessel. Make sure that
the drain tubing is at the back side
of the analysis vessel and in the
ringlets. Other tubing should be
above the liquid level.
Prepare a new set of reagents when
the reagent bottles are empty.
Flush/Prime all tubing before a
measurement is started.
Examine the dispenser. Push F2 >
Dispenser to start the dispenser
again.
Examine if the electrode is
connected correctly. Examine the
electrolyte level in the electrode,
refill if necessary.
• Examine if sample solution goes
into the vessel.
• Examine if the dispenser is filled.
• Make sure that the sensing part
of the electrode is fully in the
sample.
• Make sure that the electrode is
filled with electrolyte solution.
• Examine the level of reagents
and titrant solution. Fill if
necessary.
• Identify if the previous calibration
measured correctly (slope ok?).
• Make sure that the sample
concentration is correct.
• Identify if the vessel is clean.
Clean if necessary.
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