Instruction manual

NGA 2000 MLT Hardware
CHECK AND REPLACEMENT OF ELECTROCHEMICAL OXYGEN SENSOR
18 - 8
Emerson Process Management GmbH & Co. OHG
Instruction Manual
90002929
07/2006
❍ Place the lid on the housing, fasten the screws and close the cover.
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 concentra-
tions of oxygen.
The longer the sensor is exposed to air, the longer it will take for the sen-
sor 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.
❍ Perform adjustment of sensor (chapter 7.)
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.