Packing Maintenance; Replacing Packing - Emerson Fisher GX Instruction Manual

Instruction Manual
February 2009
Pneumatic tubing is not required because the air
passages are internal to the actuator. Also, install
the insulating gaskets around the mounting bolts.
6. Check for clearance between the magnet
assembly and the DVC2000 feedback slot. The
magnet assembly should be positioned such that the
index mark in the feedback slot of the DVC2000
housing is between the valid range on the magnet
assembly throughout the range of travel.
(See figure 4).
B. For air-to-close GX actuator (spring-to-open)
(see figure 4 and figure 20 or 21):
1. Attach the magnetic feedback array (supplied
with the DVC2000) to the valve stem connector
using the alignment template (supplied with the
mounting kit) for accurate alignment.
2. In the air-to-close configuration it is required that
an R1/8 plug be installed into the integral mount
pneumatic port on the back of the DVC2000 housing
(Port B of figure 4).
3. Remove the digital valve controller's cover.
4. Using a 6mm hex wrench, attach the digital valve
controller to the GX actuator mounting pad.
The O-ring seal and G1/4 or 1/4 NPT
plugs (supplied in the mounting kit)
are not used with this actuator
construction.
5. Check for clearance between the magnet
assembly and the DVC2000 feedback slot. The
magnet assembly should be positioned such that the
index mark on the pole pieces (back of the controller
housing) is between the marks on the magnet
assembly throughout the range of travel. (See
figure 4.)
6. Install tubing between the external pneumatic
output connection of the DVC2000 (Port A of
figure 4) to the air supply connection (see figure 20
or 21) on top of the actuator casing.
When changing actuator action:
When field converting a GX actuator from
air-to-open to air-to-close closed (or vice-versa), you
will need to change the plugs for the pneumatic
passages in the DVC2000 housing.
Note
GX Valve and Actuator
D To convert from air-to-close to air-to-open
(spring-to-close), remove the R1/8 pneumatic plug
on the back of the DVC2000 housing and install an
O-ring (Port B of figure 4). Plug the external
pneumatic output with a 1/4 NPT or G1/4 plug
(depending on the housing version). (Port A of
figure 4.)
D To convert from air-to-open to air-to-close
(spring-to-open), remove the external pneumatic
plug (1/4 NPT or G1/4 plug, depending on the
housing version from Port A of figure 4). Install an
R1/8 plug on the back of the DVC2000 housing (Port
B of figure 4). Install tubing between the pneumatic
output connection of the DVC2000 (Port A) to the air
supply connection on top of the actuator casing (see
figure 20 or 21).

Packing Maintenance

Key numbers refer to figures 15, 18, 19, 20, 21, 22,
and 23.
Packing Adjustment
For spring-loaded single PTFE V-ring packing
(figure 15) or for Graphite ULF packing (figure 16),
the Belleville spring pack (key 34) maintains a
sealing force on the packing. If leakage is detected
around the packing follower (key 29) check to be
sure that the packing follower (key 29) is tight. Using
a wrench, tighten the packing follower (key 29) in 1/4
turn intervals until the leakage is stopped. If leakage
cannot be stopped in this manner, proceed to the
Replacing Packing section in this manual.

Replacing Packing

This section provides instruction on replacing
packing in standard bonnets, extension bonnets, and
bellows extension bonnets.
Isolate the control valve from the line pressure,
release pressure from both sides of the valve body
and drain the process media from both sides of the
valve. Shut off all pressure lines to the actuator and
release all pressure from the actuator. Use lock-out
procedures to ensure that the above measures stay
in effect while you work on the equipment.
1. For air-to-open constructions:
a. Connect a separate air supply to the lower
diaphragm casing via the air supply connection
on the yoke (as shown in figure 18 or 19) and
apply sufficient air pressure to raise the valve
plug/stem off the seat to mid travel.
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