GE CGA 351, User Manual

Page: 96 / 133

December 2004
5-18 Service and Maintenance
Replacing the
Thermocouple (cont.)
6.
Extract the thermocouple from the sensor furnace, through the
opening in the bottom of the sensor enclosure.
Install the new thermocouple by completing the following steps:
1.
Insert the new thermocouple into the sensor furnace, being careful
not to strike it against the heating element or the pipe wall inside
the sensor furnace.
2.
Secure the thermocouple clamp to the bottom of the sensor
furnace with the screw previously removed.
3.
Route the thermocouple wires through the conduit and into the
electronics enclosure.
4.
Connect the thermocouple wire leads to the same pins from which
the old leads were removed. The positive (yellow) and negative
(red) leads must be connected with the correct polarity.
5.
Reinstall the oxygen sensor/manifold assembly into the bottom of
the sensor enclosure and install the upper and lower oxygen sensor
clips, as described in the previous section.
6.
Close the covers on both enclosures.
7.
Energize the main power to the meter and calibrate the oxygen
sensor (see “Calibrating the Model CGA 351” on page 4-31).
This completes the replacement of the thermocouple.
Replacing the Sensor
Furnace
The sensor furnace, which maintains the oxygen sensor at a stable
operating temperature, is located in the sensor enclosure and is easily
replaceable. The following tools are required:
•
screwdriver
•
digital multimeter
Caution!
To replace the sensor furnace, the power to the
CGA 351 must be disconnected. Therefore, replace
the sensor furnace and reconnect the power as quickly as
possible to prevent corrosion of the analyzer components
due to acid condensation.
IMPORTANT: These symbols indicate Caution - dangerously hot
surfaces and risk of electric shock, respectively:
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