Yokogawa Integral Oxygen Analyzer ZR202 - Manual (Page 158)

IM 11M12A01-05E 11-7
11. Inspection and Maintenance
Replacement of heater strut assembly
Refer to Figure 11.4 as an aid in the following discussion.
Remove the cell assembly (6), following Section 11.1.2, earlier in this manual.
Remove the two screws (15) that tighten the cover (12) and slide it to the flange side.
Remove the four bolts (10) to remove the converter (16). Then remove the three
connectors to which leadwire from the heater and thermocouple is connected.
Loosen Screw (19) until Heater Strut Assembly (23) plate can be removed.
There’s no need to remove O-ring (18) which prevents Screw (19) from coming out.
Pull out connector (13).
Loosen and remove the screw (8) with a special wrench (part no. K9470BX or equiva-
lent) and then remove the heater strut assembly (23) from the detector (24).
To reassemble the heater strut assembly, reverse the above procedure:
Insert the heater strut assembly (23) into the detector (24), while inserting the calibration
pipe in the detector (24) into the heater section in the heater strut assembly (23) as well
as in the bracket hole. Coat the screw (8) with grease (NEVER-SEEZ: G7067ZA) and
tighten the screw (8) with a special tool (part no. K9470BX or equivalent) with a
tightening torque of 12N•m 6 10 %.
Next, to install the O-rings (22) on the calibration-gas and reference-gas pipes, disas-
semble the connector (13) in the following procedure:
First, remove the screw (25) and then remove the plate (17) and two caps (20).
If the O-ring (22) remains in the hole, pull them out from the back. Pass the heater and
thermocouple leadwire through the connector (13). Also, pass the calibration-gas and
reference-gas pipes through the opening of the connector (13). If the O-ring (22) fails,
replace it with a new one.
Push the two caps (20) into the associated opening of the connector (13).
Insert the plate (17), aligning it with the groove of the cap (20), and tighten it with the
screw (25). If you attempt to insert the calibration-gas and reference-gas pipes into the
connector (13) without disassembling the connector (13), the O-ring may be damaged.
Tighten Screw (19) in Heater Strut Assembly (23) until connector (13) can’t move.
Reassemble in reverse order to the above disassembly procedure.
When installing the cell assembly (6), replace the metal O-ring (7) with a new one.
11.1.4 Replacement of O-ring
The detector uses three different types of O-rings (14), (21), and (22). One O-ring alone
(14), or two O-rings (21) and (22) are used. (For a pressure-compensating model, two O-
rings are used for individual uses. Two O-rings (21) and (22) are used for reference-gas
sealing and require periodic replacement.