4660 Pressure Pilot
Instruction Manual
Form 5200
September 2004
13
When the process pressure returns to a value
between the low and high set points, the flapper no
longer contacts one of the set point pivots, but
contacts the nozzle beam, again capping off the
relay nozzle. This resets the relay assembly,
restoring full output pressure.
Maintenance
Select the appropriate maintenance procedure, and
perform the numbered steps. Each procedure
requires that supply pressure and process pressure
be shut off before beginning maintenance. All key
numbers are shown in figure 8.
WARNING
Avoid personal injury or property
damage from an uncontrolled process
or sudden release of process
pressure. Before starting disassembly:
D
Always wear protective clothing
and eyewear when performing any
maintenance operations.
D
Provide some temporary means
of process control before taking the
pilot out of service,
D
Shut off the process pressure line
and the supply pressure line, and
bleed all the supply pressure.
D
Bleed all process pressure from
the pilot so that no pressure is
contained in the Bourdon tube.
D
Use lock-out procedures to be
sure that the above measures stay in
effect while you are working on the
equipment.
D
Check with your process or safety
engineer for any additional measures
that must be taken to protect against
process media.
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
Bourdon 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
Bourdon 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
procedures 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
assembly.
6. Tighten the machine screws.
