MODEL 300 COMBUSTION ANALYZER
Instruction 24-9223
5-3
5.2
TOXIC SENSOR REPLACEMENT
Equipment Needed (See Section 6 for Part Numbers)
• Nutdrivers, 4 mm (5/32"), & 8 mm (5/16")
•NO
X
Sensor, or
• CO Sensor, or
•SO
2
Sensor
Procedure
WARNING!
Burn hazard. The carbon monoxide sensor contains corrosive
chemicals. DO NOT puncture or take the sensor apart.
1. Remove sensor cover per Section 4.1.
NOTE:
The optional SO
2
and NO
X
sensors are located directly beneath
the O
2
and CO sensors. In order to remove these sensors, their mount-
ing bracket must be removed first. This requires removing the two 5/16
nuts, see Fig. 4-9.
2. Using a 5/32 nutdriver,
loosen
nuts that secure the wires connected to
Toxic sensor terminals C, S, and R (Fig. 5-2); then remove the wires.
3. Remove the 5/32 nuts that retain the Toxic sensor to its expansion
chamber; then remove and discard the old Toxic sensor.
4. Before proceeding, ensure that the Toxic sensor’s O-ring and mem-
brane are still positioned inside the expansion chamber.
5. Remove new Toxic sensor from its shipping container and place it over
the screws that protrude up from the expansion chamber. When
positioned properly, the sensor’s three electrical connections should be
facing up and toward the front of the analyzer.
NOTE:
The new CO and SO
2
sensors will have a shorting wire
connected between terminals R and S. DO NOT remove this wire
until instructed to do so in Step 7.
6. Use the three nuts removed in Step 3 to secure the sensor to the
expansion chamber.
DO NOT
overtighten these nuts!