Bourdon Tube/Flapper Assembly Replacement; Block-And-Bleed Relay Assembly Replacement; Low Or High Set Point Assembly Replacement; Pilots Without Set Point Indication - Fisher 4660 Instruction Manual

Type 4660
Use lock-out procedures to be sure
that the above measures stay in effect
while you are working on the equip-
ment.
Bourdon Tube/ Flapper Assembly
Replacement
Obtain the Bourdon tube/flapper assembly kit listed in
the parts kit section.
1. Remove the case cover screw (key 5) and the case
cover (key 3).
2. Unhook the flapper spring (key 18) from the Bour-
don tube/flapper assembly. Inspect the flapper spring,
and replace it if the coils are separated when the
spring is in its free state with no extension.
3. Loosen the screws (key 27), and remove the Bour-
don tube/flapper assembly.
4. Disconnect the process tubing (key 8).
5. Install a new Bourdon tube/flapper assembly and
tighten the machine screws.
6. Reconnect the process tubing to the Bourdon tube/
flapper assembly.
7. Reconnect the flapper spring to the Bourdon tube/
flapper assembly.
8. Replace the case cover, and attach it with the case
cover screw.
9. If appropriate, place a new label (key 73) with the
new Bourdon tube set range on the front plate (key
74).
10. Reset the high and/or low set points according to
the procedures presented in the Operating Information
section.
11. Refer to the alignment of the nozzle beam proce-
dures in the Operating Information section.
Block-and-Bleed Relay Assembly
Replacement
Obtain the block-and-bleed relay assembly listed in
the parts kit section.
1. Make sure supply pressure is shut off and vented.
2. Remove the case cover screw (key 5) and the case
cover (key 3).
3. Remove the machine screws (key 57).
4. Remove the block-and-bleed relay assembly.
5. Make sure the O-rings are in place on the bottom
flange, then install a new block-and-bleed relay as-
sembly.
12
6. Tighten the machine screws.
7. Refer to the alignment of the nozzle beam proce-
dure in the Operating Information section.
8. Replace the case cover, and attach it with the case
cover screw.
9. Reset the high and/or low set points according to
the procedures presented in the Operating Information
section.
Low or High Set Point Assembly
Replacement
Obtain the set point assembly listed in the parts kit
section, then perform one or the other of the following
procedures.

Pilots Without Set Point Indication

New locking wedges (key 71) must be
installed when performing this proce-
dure. Refer to the parts list section and
obtain the correct quantity. Two are re-
quired for low or high versions. Four are
required for high-low versions.
1. Perform steps 1 through 4 of the Bourdon tube/flap-
per assembly replacement procedure.
2. Remove the knob (key 67) by loosening the knob
set screw and pulling it away from the front plate (key
74).
3. Remove the locking disk (key 69) and the locking
nut (key 70).
4. Remove the screws (key 68) and the switch point
assembly.
5. Remove the locking wedges (key 71).
6. Install the new set point assembly and tighten the
screws.
7. Install new locking wedges over the set point stem.
8. Apply lubricant (key 81) to the locking nut threads
and install it finger-tight.
9. Tighten the locking nut to 50 lbf in (5.6 N m) of
torque. Back the nut out one-quarter turn.
10. Re-tighten the locking nut to 10 lbf in (1.1 N m) of
torque.
11. Install the knob on the stem and tighten the set
screws. Attempt to rotate the knob. If the knob rotates,
repeat steps 9 and 10.
12. Loosen the set screws and remove the knob.
13. Repeat steps 1 through 12 if both set point assem-
blies are to be replaced on a high-low version of the
pilot.
Note