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6.2.3. Accessing the Threaded Sensor Assembly
The loading mechanism and vent seat for the LF-690 can be accessed from the top of the regulator. Ensure
the spring is de-compressed by rotating the hand wheel fully anti-clockwise and follow the instructions
below:
i.
Remove the securing grub screw (26) from the regulator body (1).
ii.
Unscrew the pan screw (27) and remove the name plate (24) from the hand wheel (23).
iii.
Using a 24mm socket, unscrew the locknut (25) and remove the hand wheel (23) from the
adjusting screw (19).
iv.
With the regulator secured up-right in a vice, remove the bonnet (18) by using a torque wrench
or equivalent with 47mm open end.
v.
Un-screw and lift the top works from the assembly, inclusive of the bonnet (18), load spring
(17), adjusting mechanism (19,20,21,22) from the Regulator body (1).
vi.
The sensor assembly (11-16,28-30,33,35-37) can be removed from the regulator body (1) firmly
gripping the flats of the lower spring rest (13) with pliers and lifting.
vii.
If necessary, the baffle plate (7) and connector pin (4) can be withdrawn. Inspect the connector
for damage and replace if required.
viii.
Grip the flats of the lower spring rest (13) in a vice so that the vent seat nut (16) is facing upwards.
ix.
The vent seat nut (16) can be removed using a 10mm open ended spanner and the vent seat (11)
can then be removed from the sensor (15) along with the 9mm x 1mm 'O' ring (28).
x.
Inspect the vent seat (23) for damage and replace.
xi.
Replace all 'O' rings and backups (29,30,33,35-37) located on the sensor (15) and sensor holder
(14) prior to reassembly, ensuring adequate lubrication is used.
xii.
Insert the sensor (15) into the sensor holder (14).
xiii.
Apply a small droplet of Loctite 638, to the thread of the lower spring rest and screw the lower
spring rest (13) into the top of the sensor (15).
xiv.
Grip the flats of the lower spring rest (13) in a vice and tighten the sensor (15) against it using the
flats at the base of the sensor.
xv.
Secure the vent seat nut (16) using a 10mm open ended spanner.
xvi.
Place the connector pin (4) into the baffle plate (7) and locate into the regulator body, taking
care not to damage the sealing edge of the connector pin.
xvii.
After reassembling the sensor (15) and holder (14), place the assembly into the regulator body
(1) ensuring that it is firmly in place.
xviii.
Place the load spring (27) onto the spring rest (25).
xix.
Screw the top works ( 18-22 ) onto the regulator body ensuring that the adjusting screw properly
locates within the load spring (17) and using a torque wrench with 47mm open end , tighten to
120Nm.
xx.
Tighten the securing grub screw (26) against the bonnet (18).
xxi.
The hand wheel (23) can now be secured on to the adjusting screw (19) using the locknut (25).
xxii.
The name plate (24) can then be secured using the pan screw (27).
It is recommended that all parts in the repair kits are used. Any defect parts removed during the service
should be disposed of.
Replacement 'O' rings should be lubricated with suitable non-hydrocarbon grease such as Krytox GPL 205.
11
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