Second method
1.
Program the transmitter in process calibration mode.
2.
Make sure the displayed value is stable before adjusting it with that of a precision calibration
solution with a conductivity close to that of the process sample.
Maintenance
Conductivity probes are extremely reliable and do not require constant re-calibration. However, if you
observe inconsistent measurements, it is advisable to check the following:
1.
Check the wiring (see
Cable connections
on page 6)
2.
Check the transmitter programming (see
Programming the transmitter
on page 9)
3.
Check the installation of the probe (see
Probe installation
on page 7)
4.
Check the probe (Pt100 and electrodes)
Figure 8 Connector view
1
Electrodes
2
Pt100
Pt100:
Compare the resistance measured directly on the connector with the values below:
Temperature (°C)
0
10
20
30
40
50
Resistance (Ω)
100.00
103.90
107.70
111.67
115.54
119.40
Temperature (°C)
60
70
80
90
100
Resistance (Ω)
123.24
127.07
130.89
134.70
138.50
Electrodes:
Check the insulation between the two electrodes (infinite resistance when probe is
dry and exposed to air).
5.
Clean the probe. The harsh conditions in which the conductivity probes are often used makes a
periodic cleaning obligatory. This will avoid the accumulation of insulating layers at the surface of
the electrode resulting in erroneous measurements.
• For most uses, washing in hot water with a household washing up liquid is sufficient.
• Greasy or oily layers can be removed with methanol or ethanol.
• When used in solutions containing bacteria or algae, use a chlorinated cleaning product such
as bleach.
• With metallic hydroxide deposits, soak the probe for 10 minutes in a 20% nitric acid solution.
6.
Re-calibrate the probe (see
Probe calibration
on page 10)
English
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