Hach SIGMA 900, Руководство пользователя

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8837apdx_trouble.fm
Troubleshooting
Appendix A Troubleshooting
Troubleshooting the Liquid Sensor
The liquid sensor contains a high frequency sound transmitter and receiver.
High frequency sound waver are sent through the silicone pump tubing by
vibrating a piezoelectric crystal. The sound waves are received on the other
side of the tubing by a a receiving crystal which acts like a microphone. Since
sound waves travel more efficiently through a liquid than through air, the
receiving crystals get a louder signal when water passes through the sensor
tubing. The signal from the receiving crystal is converted to a voltage
proportional to the signal strength. The voltage is used by the 900
microprocessor to sent the exact moment water reaches the sensor. The
liquid sensor compares the signal strength (voltage) when the tubing is dry
(purging the line) to the signal strength when the tubing is full of water
(pumping a sample). The dry verses wet voltage readings are used to tell the
900 microprocessor when water has hit the liquid sensor.
Symptoms indicating a problem with the liquid sensor:
• Poor volume accuracy
• Overfilled bottles
• Missing Samples
• Purge Failures
• Pre-Rinse Failures
Solutions to liquid sensor problems:
• Change the pump tubing if discolored, worn, or brittle.
• Use only the manufacturer suppled tubing.
• Clean the sensor where tubing is held in place.
• Tighten thumbscrews to ensure proper compression of tubing in the
sensor body.
If these items do not resolve the liquid sensor issue, your controller may need
to be serviced or disable the sensor and select a manual-timed calibration
method.