Emerson FISHER GX Instruction Manual page 10

GX Valve and Actuator
b. Remove the stem connector nut half (key 23),
stem connector bolt half (key 24), and travel
indicator (key 26).
c. Push the valve plug stem (key 3) down until it
contacts the seat.
d. 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).
e. Shut off the air pressure and disconnect the
separate air supply to the lower diaphragm
casing (as shown in figure 15 or 16).
2. For air-to-close constructions, as shown in
figure 17 or 18, remove the stem connector nut half
(key 23), stem connector bolt half (key 24), and
travel indicator (key 26).
WARNING
To avoid personal injury or property
damage by uncontrolled movement of
the actuator yoke (key 8), loosen the
body/yoke nuts (figures 15, 16, 17, and
18, key 7) or bonnet/yoke nuts (figures
19 and 20, key 46) by following the
instructions in the next step. Do not
remove a stuck actuator yoke by
pulling on it with equipment that can
stretch or store energy in any other
manner. The sudden release of stored
energy can cause uncontrolled
movement of the actuator yoke.
The following step also provides
additional assurance that the valve
body fluid pressure has been relieved.
3. For standard bonnet constructions (figures
15, 16, 17, and 18), body nuts (key 7) attach the
actuator yoke (key 8) to the valve body (key 1).
Loosen these nuts approximately 3mm (1/8 inch).
For extension and bellows bonnet constructions,
bonnet nuts (key 46) attach the actuator yoke (key 8)
to the extension bonnet (key 39). Loosen these nuts
approximately 3mm (1/8 inch).
10
Note
4. Then loosen the valve-to-yoke gasketed joint by
either rocking the actuator yoke or prying between
the valve and actuator yoke. Work the prying tool
around the actuator yoke until it loosens.
WARNING
If there is evidence of process fluid
under pressure leaking from the joint,
retighten the valve body/joint nuts and
return to the Warning at the beginning
of the Maintenance section to ensure
proper steps have been taken to
isolate the valve and relieve process
pressure.
5. If no fluid leaks from the joint, loosen the packing
follower (key 29) two turns to relieve the packing
compression load.
6. For standard bonnet constructions (figures
15, 16, 17, and 18), remove the body nuts (key 7)
completely.
For extension and bellows bonnet constructions
(figures 19 and 20), remove the bonnet nuts
(key 46) completely.
CAUTION
To avoid property damage, place the
actuator yoke on a protective surface,
as described in the following
procedure.
7. Carefully lift off the actuator yoke and set it on a
protective surface to prevent damage.
For standard bonnet constructions, if the bonnet
(key 4) together with the valve stem plug assembly
has a tendency to lift with the actuator yoke, ensure
it does not drop from the actuator.
For extension and bellows constructions, ensure
the bonnet (key 4) does not lift with the actuator
yoke.
For DN150 balanced constructions, if the bonnet,
guide sleeve, or valve stem assembly have a
tendency to lift with the actuator yoke, ensure they
do not drop from the actuator.
CAUTION
For extension and bellows bonnet
constructions, lifting the bonnet with
Instruction Manual
Form 5770
June 2006