Emerson Process Management 3024C - Manual (Page 8)

3024C Actuator
Instruction Manual
Form 5760
March 2007
8
WARNING
Avoid personal injury or property
damage from sudden release of
process pressure or bursting of parts.
Before performing any maintenance
operations:
D Always wear protective gloves,
clothing, and eyewear when
performing any maintenance
operations to avoid personal injury.
D Disconnect any operating lines
providing air pressure, electric power,
or a control signal to the actuator. Be
sure the actuator cannot suddenly
open or close the valve.
D Use bypass valves or completely
shut off the process to isolate the
valve from process pressure. Relieve
process pressure from both sides of
the valve. Drain the process media
from both sides of the valve.
D Vent the power actuator loading
pressure and relieve any actuator
spring precompression.
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.
Disassembly
1. For complete disassembly, the positioner and all
accessories (if attached) must be removed from the
actuator. Follow appropriate removal procedures in
the instruction manuals supplied with the positioner
and accessories.
2. Bypass the control valve. For a top-loaded Type
3024C Air-to-Close actuator reduce the diaphragm
air pressure to zero and remove the piping or tubing
from the connection in the upper diaphragm casing
(key 16). For a bottom loaded Type 3024C
Air-to-Open apply air pressure to the diaphragm to
open the valve.
Note
When disassembling the stem
connector on Air-to-Open
constructions it is essential to apply
enough air pressure to the underside
of the diaphragm to lift the valve plug
off its seat. This will ensure that all
residual spring compression in the
actuator is supported while the stem
connector is removed.
3. Undo the stem connector by first slackening the
valve stem locknuts and then removing the socket
bolts.
4. Undo the yoke locknut on the valve bonnet and
carefully lift the actuator off the valve. As you undo
the yoke locknut, ensure that the actuator is properly
supported. If the actuator is a bottom loaded
Air-to-Open type, reduce the diaphragm pressure to
zero and remove the piping or tubing from the
connection in the lower diaphragm casing (key 1).
5. Slightly loosen all diaphragm casing cap screws
(key 19 and 21). Remove the plastic hose (key 22).
Unscrew the short and long diaphragm casing cap
screws and nuts (keys 19, 20 and 21) alternately,
until only the long casing cap screws (key 21)
remain engaged. Then allow the remaining spring
compression to be slowly released by alternately
unscrewing the long casing cap screws.
6. When removing the diaphragm and actuator
springs perform one of the following procedures as
appropriate:
For a Type 3024C Air-to-Open Actuator
(figure 9)
a. Lift off the upper diaphragm casing (key 16),
the casing spacer (key 29) and seal ring (key 30)
if fitted (see figure 13), and remove the springs
(Key 15).
b. Using a strap wrench or soft-jawed vice, hold
the actuator stem (key 8) and remove the travel
stop nut (key14).
c. Remove the diaphragm plate (key 13),
diaphragm (key 11), O-Ring (key 12), pressure
plate (key10) and the split ring halves (key 9).