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General
These instructions apply to the 75000 Series tank mount type
control valves.
For the construction of the valve body, please refer to the
drawings MNS139003 and MNS 139006, on page 3 and 4. For
the cylinder actuator, side handwheel, and other components,
refer to the respective instructions.
This control valve is designed to be mounted directly on a
container like storage tank, and the seat ring and the plug are
to be installed from the bottom of the valve body. The valve
operates such that it "closes as the stem rises".
Installation
Prior to installing the valve, clean the piping of all foreign matter
such as dirt, welding chips, scale, oil or grease. Install the valve
to the piping so that the fluid flows in the direction indicated by
the flow arrows attached to the body, or the fluid flows from "IN"
toward "OUT" marked at the connection point. When securing
the lower flange to the tank, press the seat ring against the body
until it enters the connection port of the tank. Be careful so that
the seat ring is not pressed too hard against the inner surface
of the connection port of the tank.
When the valve is installed in a horizontal position, be sure to
support the yoke or another part of the actuator.
In case of the extension type body, do not apply insulation to the
extended portion.
Provide the required air tubing for the signal pressure and air
supply, and the electrical wiring to the positioner. Make sure
there are no air leaks from the piping.
Maintenance
When the control valve needs to be disassembled for inspection,
cleaning or polishing the valve seat, follow the procedures
described below.
The following procedure is according to the drawings
MNS139003 and MNS 139006, on page 3 and 4.
Disassembly
Shut off all the air supplies, and disconnect the tubings for the
air supply and the positioner signal pressure, and the air tubing
from the volume tank.
To disassemble the valve, it must be removed from the piping.
Bring a chain block over the valve to remove it from the piping
for disassembly and for reinstallment.
1. Run a strong rope through the actuator yoke and remove the
valve retaining bolts from the piping while slightly pulling the
valve upward.
If the valve is installed in a horizontal position, also run a
rope around the body so that no excessive force is exerted
on the seat ring in the tank, when disconnecting the valve
from the tank.
2. Remove the positioner linkage from the split clamp (18)
which connects the piston rod (19) of actuator and the
plug (13) of the body side. Loosen the nut (16) or the bolt
(26), depending on the assembly method of the split clamp
(see drawing MNS-139003 & MNS-139006), to remove the
split clamp (18). Record the depth of the stem in the split
clamp and the position of the split clamp so that they can be
reassembled to the same dimension. Loosen the set screws
(28) for easy reassembly.
3. Remove the nuts(27) from the plug. Remove the plug (13),
followed by the seat ring (12) from the bottom of the body.
The actuator can be removed by loosening the drive nut (5),
which connects the body (10) and the yoke (14). If the yoke
is connected to the body with the stud (23) and nut (24),
loosen the nut (24) to remove the actuator from the body.
Polishing the Valve Seat
When the valve seat needs polishing, install the seat ring (12)
and plug (13) from the bottom of the body (10), and tentatively
hand-tighten them to the body. Lightly press the plug (13)
against the seat side from the bottom of the body (10), hold the
plug with a wrench at the wrench holder, and polish the seating
surface. Polishing the seating surface too hard may damage
the seating surface. When polishing the seating surface, apply
a fine-grain, quality abrasive to it. Thoroughly clean the seating
surface prior to reinstallation.
Reassembly
When reassembling the valve, replace the gland packing (6)
and gasket (11) with new ones where possible. If the valve is
gasketless, remove all foreign objects such as dirt, grease,
etc. Reassembly is basically done by reversing the process
of disassembly. However, the following steps for reassembly
should be taken:
If the flange is a threaded type, it must be screwed
about 5 mm from the body’s end to give adequate
compression to the gasket. Please refer to figure 1.
To prevent any equipment damage or troubles, follow
the instructions below.
a) The valve must not be used when exceeding the
applied regulations, standards and criterion.
b) The valve must not be used in any condition other
than the agreed specifications.
c) If the heat transfer medium in the jacket is an
incompressible fluid, do not increase the pressure
above the agreed specification or expand the
fluid when closing the inlets/outlets of the jacket.
Please refer to the drawing MNS-139006 on page 4.
