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Page 20
9.2 pH Troubleshooting
Symptom
Possible Causes
Remedy
Asymmetry (Zero)
calibration fails
(insufficient range
with
ZERO
control).
1. Reference junction blocked.
2. Reference electrolyte
contaminated.
Clean reference junction, as per
instructions supplied with the
electrode.
Flush with distilled water and
replace electrolyte.
Span calibration
fails (insufficient
range with
SPAN
control).
1. ATC probe not connected.
2. Glass bulb not clean.
3. Electrode is aged.
4. Buffers are inaccurate.
Connect ATC probe to
terminals 1 & 2 (see section
3.4).
Clean glass bulb as per
instructions supplied with the
electrode.
Attempt rejuvenation, as per
instructions supplied with the
electrode. If not successful,
replace electrode.
Replace buffers.
Unstable readings.
1. Solution guard not fitted.
2. Reference junction blocked.
3. Glass bulb not clean.
4. Bubble in glass bulb.
5. Reference junction not
immersed.
6. KCl crystals around
reference junction, inside
the electrolyte chamber.
Connect the green wire from
the ATC (or solution guard rod
if no ATC sensor is fitted), to
terminal 3 (see section 3.4).
Clean reference junction, as per
instructions supplied with the
electrode.
Clean glass bulb as per
instructions supplied with the
electrode.
Flick the electrode to remove
bubble.
Ensure that the bulb AND the
reference junction are fully
immersed.
Rinse electrolyte chamber with
warm distilled water until
dissolved. Replace electrolyte.
Inaccurate readings,
even when
calibration is
successful.
Reference junction blocked.
Clean reference junction, as per
instructions supplied with the
electrode.
Displays around 7
pH in all solutions
Electrical short inside electrode
or in cable.
Test system with a new
electrode and replace if
necessary.
Displays 4-5 pH for
all solutions.
Glass bulb or internal stem
cracked.
Replace electrode.
Содержание miniCHEM-pH
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