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Masoneilan 48000 Series Top Guided Globe Valve | 3
5. Air Piping
The actuators are designed to accept 1/4" NPT air supply
piping. Use 1/4" OD tubing (4 x 6 mm) or equivalent for all air
lines. If the supply air line exceeds 25 feet in length (7 meters)
or if the valve is equipped with volume boosters, then 3/8"
tubing (6 x 8 mm) is preferred. AII connections must be free
of leaks.
Do not exceed supply pressure indicated on serial plate
located on the yoke of the actuator.
6. Actuator Assembly
Assemble the actuator onto the control valve using the
appropriate instructions for the specific actuator model
and type. Connect air pressure lines to the actuator ports
to meet intended operating mode (i.e., air-to-extend, air-
to-retract, or double-acting).
7. Disassembly
Prior to performing maintenance on the valve, isolate the
valve and vent the process pressure.
7.1 Valve actuation
Access to the internal components of the valve should be
accomplished with the actuator removed. Follow the
detailed instructions below and refer to the appropriate
actuator instruction manuals.
Actuator may be pre-loaded with tension from air pressure
or springs. Prior to disconnecting instrumentation read all
instructions for the specific actuator.
7.2 Disconnect Instrumentation
Disconnect all mechanical connections between the
positioner and the other instruments. Disassemble the valve
stem and actuator stem coupling as described in the
following sections.
7.3 Air-to-Retract Actuators
Apply sufficient air pressure to the actuator to retract the
stem completely. Disconnect the plug stem from the
actuator stem depending on the connection type as
described below.
Threaded Connection
Unscrew the plug stem from the actuator stem, making sure
the plug never contacts the seating area at any time during
disassembly.
Contact between the plug and seating area during this
disassembly process may cause damage to the seating
surfaces. It may be necessary to disassemble the actuator
yoke from the valve bonnet and lifting the actuator off the
valve to avoid plug to seating surface contact.
S
tem Connector
Remove the screws and disassemble the stem connector from
the valve and actuator stems.
7.4 Air-to-Extend Actuators
For this actuator configuration, the valve plug is already in the
fully retracted position without any air pressure applied.
Disconnect the plug stem and actuator stem as described in the
threaded connection and stem connector sections above
depending on the connection type.
7.5 Actuator Removal
Disconnect all electrical and air connections to and from the
actuator. Disassemble yoke nut or yoke attachment screws,
and lift the actuator off of the valve being careful not to
damage the bonnet threads.
7.6 Valve disassembly
The valve must always be reassembled with new packing set
and gaskets. Before disassembly, make sure the
recommended spare parts are available for reassembly.
A.
If there is a leak detector connection on the lateral NPT
port of the bonnet, disconnect this piping as well.
B.
Remove body stud nuts (19).
C.
Remove packing flange nut (3), packing flange (4), and
packing follower (5).
D.
Remove bonnet (18).
Take care at this point, because the plug subassembly may
come out together with the bonnet.
Note:
Spiral wound body gaskets (9) are standard in the
48000 Series design and it is imperative that a new gasket be
installed each time the valve is disassembled.
E.
Lift up plug stem (1) and separate plug (15) from the valve.
Care must be taken to avoid damage to the plug and plug
guide.
F.
Remove body gasket (9) and lift out cage (16) by its lifting
holes. If seal rings (10, 11) are hard to remove, place
subassembly on a level base with rags or cardboard
spread on top to avoid scratching the underside of the
plug and cage. Then either use a press to push down plug
stem or tap plug stem lightly with a wooden or plastic
hammer. Inspect the seal rings (10, 11) and replace them if
worn. (48200 Unbalance Type valve is not provided with a
seal ring.)
G.
Remove body gasket (9).
H.
Loosen seat ring retainer (13) with special tool and remove
it. Because seat ring retainer (13) is provided with right-
handed thread, loosen it by turning it firmly to the left.
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