Instruction manual

NGA 2000 MLT Hardware
MEASURING PRINCIPLE
2 - 14
Emerson Process Management GmbH & Co. OHG
Instruction Manual
90002929
07/2006
Notes for analyzers with electrochemical TEO
2
cell!
For TEO
2
sensor please note that the gas inlet and outlet connections of the analyzer are sealed to prevent
exposure of the sensor to air.
Prolonged exposure of the sensor to air can cause extended start up time, reduction of performance or
damage to the sensor. Do not remove the sealing caps until all associated sample handling components
are installed and the instrument is fully ready for installation.
After replacement purge gas paths with inert gas (nitrogen (N
2
)) or sample gas as soon as possible to avoid
prolonged exposure of the sensor to high concentrations of oxygen.
The longer the sensor is exposed to air, the longer it will take for the sensor to recover to low ppm levels.
When installing a new sensor or starting the instrument for the first time, it may take as long as eight hours
for the analyzer to purge down to the lowest operating range.
Prolonged exposure of the sensor to air can cause extended start up time, reduction of performance or
damage to the sensor.
After initial startup or startup following a prolonged shutdown, the analyzer may require extended time to
recover to the range of measurement. Commonly, this is caused by the introduction of ambient air into the
sample and/or vent lines to the sensor. The presence of higher than normal levels of oxygen at the sensor
will cause the sensor electrolyte to become saturated with dissolved oxygen. When the instrument is placed
in operation, the sensor must now consume all excess dissolved oxygen above the desired measuring
level.
All analyzers with electrochemical TEO
2
cell have to be purged with inert gas (Nitrogen, N
2
) prior to
disconnect the gas lines ! Then the gas line fittings have to be closed for transport or depositing analyzer.
OXYGEN MEASUREMENT