Hach-Lange ISENH418103 User Manual - Manual (Page 11)

Message or symptom Possible cause Action
Slow response time
Dirty sensing element Clean the probe (refer to Clean the probe
on page 10).
Low sample temperature or
temperature difference between
samples Check the sample temperature. The lower the
temperature or the greater the difference of
temperatures between samples, traditionally the
longer the response time.
Bubbles trapped under sensor tip Gently shake the probe until bubbles are removed
from under sensor tip.
Slope out of range (refer to
Check probe response
on page 12)
pH is incorrect Verify the pH is < 8.5 after each ISA addition.
Ionic strength adjustor (ISA) not
used Add ISA to each sample and standard (one powder
pillow per 25 mL of solution).
Insufficient conditioning Condition for at least 5 minutes in a 100 mg/L
standard solution with ISA.
Damaged probe Contact a Technical Support Representative.
Incorrect standards Calibrate using freshly prepared standards.
Dirty sensing element Clean the probe and recalibrate.
Bubbles trapped under sensor tip Gently shake the probe until bubbles are removed
from under sensor tip.
Drifting/inaccurate readings
Dirty sensing element Clean the probe (refer to Clean the probe
on page 10).
Clogged reference Rinse reference junction with deionized water
thoroughly and shake the probe downward to
remove any air bubbles. The air bubbles will not be
visible.
Improper storage conditions Clean or condition the probe and attempt another
calibration. To re-condition the probe and reference
junctions, allow the probe to soak in a conditioning
solution (that contains ISA) for at least 30 minutes
prior to use.
Stabilization criteria not optimized
for the application Adjust the stabilization criteria in the measurement
options menu.
Magnetic stirrers may generate
sufficient heat to change solution
temperature. Put a piece of insulating material between the stirrer
and beaker.
Damaged probe Contact a Technical Support Representative.
Electromagnetic Forces (EMF) from
items such as voltaic cells,
thermoelectric devices, electrical
generators, resistors and
transformers Do not use in areas where EMF is present.
Bubbles trapped under sensor tip Gently shake the probe until bubbles are removed
from under sensor tip.
Out of range Measurement value is outside of
range Make sure that the sample is within the range of the
probe.
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