Actuator Maintenance - Emerson FISHER GX Instruction Manual

GX Valve and Actuator
D Use lock-out procedures to be
sure that the above measures stay in
effect while you work on the
equipment.
D The valve packing box may
contain process fluids that are
pressurized, even when the valve has
been removed from the pipeline.
Process fluids may spray out under
pressure when removing the packing
hardware or packing rings, or when
loosening the packing box pipe plug.
D Check with your process or safety
engineer for any additional measures
that must be taken to protect against
process media.
Whenever a gasket seal is disturbed
by removing or shifting gasketed
parts, install a new gasket during
reassembly. This ensures a good
gasket seal because the used gasket
may not seal properly.

Actuator Maintenance

The following sections provide procedures for
actuator maintenance. Refer to figures 15, 16, 17,
and 18.
The actuator soft parts may require periodic
replacement. This includes the diaphragm (key 10),
actuator rod bushing (key 19), and the actuator rod
seal (key 20).
If the actuator stroking direction (air-to-open or
air-to-close) is unknown, refer to the nameplate on
top of actuator casing and figure 2.
When the GX actuator is equipped with
the integrated FIELDVUE DVC2000
Series digital valve controller (figure
1), additional considerations may be
required. Refer to the FIELDVUE
DVC2000 Digital Valve Controller
Mounting section of this manual for
additional instruction.
4
Note
Note
Actuator Disassembly (For Air-to-Open
Constructions - see figures 15 or 16)
1. Connect a separate air supply to the lower
diaphragm casing via the air supply connection on
the yoke (as shown in figure 15 or 16) and apply
sufficient air pressure to raise the valve plug/stem off
the seat to mid-travel.
2. Remove the stem connector nut half (key 23),
stem connector bolt half (key 24), and travel
indicator (key 26).
3. Push the valve plug/stem (key 3) down until it
contacts the seat.
4. Loosen the locknut (key 28) and thread the stem
adjustor nut (key 27) down until it clears the top of
the valve plug/stem (key 3).
5. Shut off the air pressure and disconnect the
separate air supply to the lower diaphragm casing
(as shown in figure 15 or 16).
WARNING
To avoid personal injury or property
damage due to actuator springs (key
12) being under compression, remove
the long cap screws (key 16) last.
The upper actuator casing may remain
fixed to the diaphragm and lower
casing during disassembly, even if the
casing cap screws have been
loosened. If this happens, the actuator
springs are still under compression.
The upper casing could suddenly
come loose and jump, due to the
compressed energy of the springs. If
the upper casing is stuck to the
diaphragm and lower casing when you
begin loosening the casing cap
screws, pry the casings apart with a
prying tool. Always ensure that the
springs are dispersing energy and the
upper casing is moving against the
long bolts during disassembly.
6. Remove the short actuator casing cap screws
and hex nuts (keys 17 and 18) first. Once these
have been removed from the actuator assembly,
carefully remove the long actuator cap screws and
hex nuts (keys 16 and 18), alternating between them
to gradually release the spring energy
(compression).
7. Remove the upper diaphragm casing (key 9) and
the actuator springs (key 12).
8. Lift off the actuator stem/diaphragm assembly
(includes keys 22, 11, 10, 14, 13, and 15) and
Instruction Manual
Form 5770
June 2006