Second Method - Hach POLYMETRON Serie Manual Del Usuario

5.5.2.2 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.
Section 6 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
2. Check the transmitter programming (see
3. Check the installation of the probe (see
4. Check the probe (Pt100 and electrodes)
Figure 8 Connector view
1 Electrodes
Pt100: Compare the resistance measured directly on the connector with the values below:
Temperature (°C)
Resistance (Ω)
Temperature (°C)
Resistance (Ω)
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
Cable connections on page 6)
Programming the transmitter
Probe installation
0 10
100.00 103.90
60
123.24 127.07
Probe calibration
on page 7)
2 Pt100
20 30
107.70 111.67
70 80
130.89
on page 10)
on page 9)
40 50
115.54 119.40
90 100
134.70 138.50
English 11