Panametrics CGA 351, User Manual, Page: 88 / 119

Chapter 5.
82 CGA 351 User’s Manual
• 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:
Replacing the Sensor Furnace (cont.)
Complete the following steps, in the order given, to remove the old sensor furnace:
1. Disconnect the main power to the CGA 351.
WARNING!
Failure to cut the main power at the external
disconnect device before proceeding will result in
serious personal injury.
2. Open the cover on the sensor enclosure.
WARNING!
The sensor furnace may still be hot. Always use
heat-resistant gloves when handling it.
3. Remove the oxygen sensor/manifold assembly and the thermocouple, as described in the previous sections
(see page 80 and page 81).
Note: For information regarding component locations and/or wiring connections in an optional enclosure, see
Appendix C.
4. Free the sensor furnace from its mounting bracket by removing the two screws on the top and bottom of the
furnace, and lift the sensor furnace out of the enclosure.
5. Locate the ceramic block on the bottom of the sensor furnace and loosen the two (2) terminal screws closest to
the outer edge of the sensor furnace.
IMPORTANT: Do not completely remove the terminal screws from the ceramic power block.
6. Carefully remove the two leads from the loosened terminal screws near the outer edge of the sensor furnace.
This completes the removal of the old sensor furnace. Install the new sensor furnace immediately, by completing the
following instructions:
1. Locate the ceramic block, which is located on the bottom surface of the new sensor furnace.
2. Feed each of the previously removed sensor furnace wires through the outside, then the inside, of the ceramic
block. Reconnect the two wires to the outer terminals on the ceramic block.
Replacing the Sensor Furnace (cont.)
3. Make sure the internal power leads are fed all the way through the ceramic block, in order to make a good
connection, and that they exit on the opposite side from which they were inserted. Tighten all four (4) terminal
screws on the ceramic block.
4. Using a digital multimeter, check the resistance of the sensor furnace heating element. Specific instructions may
be found on page 73.
5. Reinstall the thermocouple and the oxygen sensor/manifold assembly into the sensor enclosure, as described on
page 80 (starting with step 3).
6. Close the cover on the sensor enclosure.
7. Reconnect the main power to the unit and recalibrate the oxygen sensor (see
Calibrating the CGA 351 on
page 62).
This completes the replacement of the sensor furnace.