Teledyne BDS-3960 - Oxygen analyzer - Manual (Page 63)

Oxygen Analyzer Maintenance
Teledyne Analytical Instruments 63
Read higher than expected (1), (2), (3)
Read lower than expected (2), (3)
Read negative (3), (4)
Noise signal (3), (5)
Slow response (5)
Causes and solution keys:
(1) Gas leak: Make sure to use new VCR gaskets, high quality
valves and gas regulator for the sampling system. Tighten each
connection.
(2) Improper gas flow rate: adjust the inlet pressure to obtain 0.5 –
1 SLPM flow rate.
(3) Improper calibration of the analyzer: Press the SYSTEM
button on Main menu screen of the PPC to bring the System
screen. Then press the “Set default” button. This will return the
analyzer to its defaults settings in calibration and zero values.
Recalibrate the analyzer with a high quality standard gas if it is
necessary. Be warned this will set defaults to ranges and alarms
settings as well.
(4) Just after adding water: The analyzer will recover by itself.
(5) Gas entered and is trapped in the sensor: This could happen if
the sensor is filled with the electrolyte improperly, or the sensor
is pressurized because of a clogged vent. To remedy this
situation, uninstall the sensor and take off the cap carefully, then
apply a vacuum degas process as shown in the Figure 5-4.
Degassing in a 28 inch mercury vacuum for 5 minutes is
sufficient to remove the gas bubbles. Reinstall the sensor into the
analyzer.
Note: A low cost vacuum degas kit (TAI P/N B72098) is available
from Teledyne Analytical Instruments.