8
Troubleshooting
8.1
Troubleshooting
In the event that the probe appears to function abnormally, this section may be
of use in solving the problem. Several possible problem conditions are de-
scribed along with likely causes and solutions. If a problem arises, please read
this section carefully and attempt to understand and solve the problem. If the
probe seems faulty or the problem cannot otherwise be solved, contact a Hart
Scientific Authorized Service Center (see Section 1.4). Be sure to have the
model number and serial number of your probe available.
Problem
Causes and Solutions
Data changes greater than 0.1°C
are observed
Mechanical shock can cause temperature errors as great as 0.5°C. If
this is observed, first measure and record the R
tp.
Next anneal the
PRT at 965°C for four hours. Measure the R
tp
again. The annealing
should decrease the R
tp
. If the R
tp
is stable, recalibrate the PRT.
Data changes less than 0.1°C
Slight mechanical shock can cause temperature errors less than
0.1°C. If this is observed, first measure and record the R
tp.
Next an-
neal the PRT at 965°C for four hours. Measure the R
tp
again. The an-
nealing should decrease the R
tp
. Repeat the annealing, R
tp
measurement cycle several times. When the R
tp
is stable, recalibrate
the PRT. If the R
tp
does not stabilize, contact a Hart Scientific Autho-
rized Service Center (see Section 1.4).
Oxidation of the platinum sensor may occur after prolonged use be-
tween 200 – 450°C. This oxidation will demonstrate itself by an in-
crease in R
tp
of less than 0.1°C. To reduce the effects of oxidation,
anneal the PRT at 600 – 661°C for 4 hours. Measure the R
tp
again.
Repeat the annealing, R
tp
measurement cycle several times This an-
nealing process should return R
tp
to within calibration tolerances. If
the R
tp
is within calibration tolerance, the PRT is usable. If the R
tp
is
not within calibration tolerance, but it is stable, recalibrate the PRT.
Data unstable
If the data is unstable at the Triple Point of Water (TPW), check the
connector. If the connector is correct, contact a Hart Scientific Autho-
rized Service Center (see Section 1.4). The PRT may be damaged
and need repair.
If the data is unstable at high temperatures, it may be due to electrical
noise in the system. Reduce the temperature and observe the data. If
it is stable, electrical noise is interfering with the measurements at
high temperatures. Check the grounding of the readout device and the
heat source. A faulty ground on either device could interfere with high
temperature measurements. Use of a clamp-on ferrite on both ends of
the lead-wire may reduce noise interferance. If the data remains un-
stable at high temperatures, determine the source of the interferance
and resolve the issue.
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8 Troubleshooting
Troubleshooting