Yokogawa Integral Oxygen Analyzer ZR202 - Manual (Page 166)

<11. Inspection and Maintenance>
11-6
IM 11M12A01-02E
Replacement of heater strut assembly (ZR22G : Style S2 and after)
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. Open the terminal
box (16) and remove the three terminal connections – CELL +, TC + and TC -.Before disconnect
the HTR terminals, remove the terminal block screw (28). Keeping the other terminal remaining
to be connected. Disconnect the two HTR connections. (These terminals have no polarity.)
Remove the two screws (15) that fasten the cover (12) and slide it to the flange side.
Remove the four bolts (10) and terminal box (16) with care so that the already disconnected wire
will not get caught in the terminal box.
In case of the pressure compensation type detector, remove the screw (36) and the plate (37) on
the adapter (35). Remove the adapter (35), drawing out the wires of the heater strut assembly
(23) from it.
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 equivalent) 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 ± 10%.
Next, to install the O-rings (22) on the calibration gas and reference gas pipes, disassemble 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-rings (22)
remains in the hole, pull them out from the back. Pass the heater and thermocouple lead wire
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 the screw (19) in heater strut assembly
(23) until connector (13) can’t move.
Reassemble in reverse order to the above disassembly procedure.
The two wires with ceramic insulators from the heater strut assembly are heater wires, and the
single-core shielded wire is the cell signal + terminal; for the two-core shielded cable, the semi-
translucent rubber-sheathed wire is the thermocouple + terminal, and the other wire is the
− terminal. (If the wires are marked, match the markings with those on the terminal board).
When installing the cell assembly (6), replace the metal O-ring (7) with a new one.
11.1.4 Replacement of Dust Filter
Set the dust filter (1) in place using a special pin spanner (with a pin 4.5 mm in diameter: part no.
K9471UX or equivalent). If a dust filter that has already been replaced once is used again, apply
grease (NEVER SEEZ: G7067ZA) to the threads of the dust filter.
11.1.5 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 and calibration gas
sealing and require periodic replacement.
8th Edition : Jan.13,2012-00