Hach Ultra ORBISPHERE 3658, Operator'S Quick Manual

Page: 11 / 16

Page 11
The following table lists possible measurement errors.
The following are warning messages that may appear on the instrument LCD in place of the gas
concentration measurement.
Troubleshooting (cont)
Symptom Cause Possible Solution
Unstable
measurement
Degassing Adjust sample flow rate
Flow chamber and/or membrane not clean Clean system
Sensor’s membrane not tight smooth and
wrinkle free
Replace membrane and recalibrate
Leaking solenoid valve
No gas bubbles should escape from the purge gas
outlet during measurement. If the solenoid leaks
(more than 1 bubble in 15 seconds) contact your Orbi-
sphere representative.
An external power supply is used but the
power supply is not clean
Switch to battery power
Low readings
Sample flow rate too low Check flow rate
Degassing Adjust forcing gas and/or sample flow rate
Membrane is not at sample temperature
Allow sample to flow past the membrane to make sure
the membrane is at sample temperature before mak-
ing measurements
Membrane not clean Clean system
Incorrect solubility curve Change solubility
Incorrect calibration Recalibrate
High readings
Membrane is not at sample temperature
Allow sample to flow past the membrane to make sure
the membrane is at sample temperature before mak-
ing measurements
Incorrect solubility curve Change solubility
Incorrect calibration Recalibrate
Message Meaning
Pur
This message appears on the LCD if the purge gas supply fails. To detect this condition, the voltage
signal from the TC sensor is measured. This is normally between 1-3 volts, depending which gas is
being measured.
If the flow of purge gas stops, the sensor voltage wanders outside the permitted range of 100mV to 4 V.
Out
This message appears if the sensor is unplugged from its correct position, or if the temperature is
outside the range -5°C to 100°C.
Err
During start-up, this message indicates the instrument cannot complete the start-up tests successfully.
If the problem persists, contact your local Orbisphere service representative for assistance.
During calibration, this message indicates that the partial pressure of gas is below the acceptable range
(<5 mbar), or that you have pressed a wrong key.