Hach PHC281, User Manual

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Section 8 Maintenance
Regular maintenance is necessary for the best accuracy, stabilization time and life of the probe.
Keep the probe in the recommended storage solution between measurements.
8.1 Clean the probe
N O T I C E
Probes with an open reference junction can become permanently damaged if the reference junction
is soaked for a long time in a cleaning solution. Make sure to soak the probe below the reference
junction only.
Clean the probe regularly to remove contamination and to keep the reference junction open.
Symptoms of contamination:
• Incorrect or irregular readings
• Slow stabilization times
• Calibration errors
• Sample material stays on the probe
1. Rinse the probe with deionized water. Use warm (35–45 °C (95–113 °F)) deionized water to
remove storage solution that dries on the probe. Dry the probe body with a lint-free cloth.
2. Soak the probe below the reference junction in the applicable cleaning solution for the specified
time. Do not let the reference junction soak in the cleaning solution or the probe can become
permanently damaged. Refer to
Figure 4 , Table 1 and Consumables on page 15.
3. Rinse or soak the probe for 1 minute in deionized water. Dry the probe body with a lint-free cloth.
4. Soak the probe in pH 4 buffer for 20 minutes.
5. Rinse the probe with deionized water. Dry the probe body with a lint-free cloth.
Figure 4 Soaking depth for open junction probes
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