249W Level Sensor
Instruction Manual
Form 5729
March 2005
11
provide a suitable means of
supporting the displacer to prevent it
from dropping into the vessel or cage
and being damaged.
1. After following the proper procedure to remove
the sensor and the displacer from the process vessel
or displacer cage, move the sensor assembly to a
suitable maintenance area. Support the assembly to
avoid damage to the displacer, displacer stem,
displacer rod assembly, and associated parts.
2. Remove the controller/transmitter and displacer
(key 4). Then, remove the hex nuts (key 20) that
hold the torque tube arm (key 2) to the wafer body
(key 1). Separate the torque tube arm from the wafer
body.
3. Using the proper tool, loosen and then remove
the upper bearing driver bolt (key 8). Lift the
displacer rod/driver assembly from the knife edge of
the driver bearing (key 7). Separate the displacer
rod/driver assembly from the end of the torque tube
assembly (key 3).
4. If necessary, remove the bearing driver by
removing the lower bearing driver bolt. Install a new
bearing driver and bolts.
5. If necessary, replace the displacer rod/driver
assembly and install it on the knife edge of the
bearing driver. Carefully fit the keyed shaft on the
bearing end of the displacer rod into a socket on the
outside of the welded end of the torque tube
assembly.
6. Install the sensor and controller/transmitter.
Calibrate the controller/transmitter following the
procedures given in the controller/transmitter
instruction manual.
Replacing the Torque Tube
Corrosion or leakage through the outer end of the
torque tube is evidence of deterioration in the torque
tube assembly (key 3) or torque tube end gasket
(key 13). Erratic or nonexistent rotary shaft output
may occur if the socket on the inner end of the
torque tube assembly does not engage the bearing
end of the displacer rod/driver assembly (key 5).
1. After following the proper procedure to remove
the sensor and the displacer from the process vessel
or displacer cage, move the sensor assembly to a
suitable maintenance area. Support the assembly to
avoid damage to the displacer, displacer stem,
displacer rod assembly, and associated parts.
2. Remove the controller/transmitter and displacer
(key 4). Then, remove the hex nuts (key 20) that
hold the torque tube arm (key 2) to the wafer body
(key 1). Separate the torque tube arm from the wafer
body.
3. Remove the nuts (key 18) and retaining flange
(key 14) holding the positioning plate (key 15) at the
end of the torque tube arm.
CAUTION
If the displacer is still attached to the
displacer rod at this point, be careful
not to let the torque tube assembly
slip when using the screwdriver
leverage procedure in steps 4 and 6.
Sudden release of the displacer could
cause damage to the displacer or
torque tube assembly.
4. Remove the positioning plate (key 15) by freeing
its two lugs.
The vertical lug fits into a hole in the flange of the
torque tube arm (figure 15). The horizontal lug
(hidden behind the screwdriver in figure 15) fits into
a slot in the outer tube end of the torque tube
assembly (the figure 15 exploded view shows this
lug to the right of the outer tube end).
The positioning plate may be pried away from the
torque tube arm and outer tube end if the displacer
already has been disconnected from the displacer
rod. However, if the displacer is still connected to the
displacer rod, place a screwdriver blade in the slots
of the positioning plate and outer tube end as shown
in figure 15. Slowly turn the positioning plate to
release its lug from the torque tube arm. Then,
carefully turn the plate back to allow the displacer to
come to rest and slip the other lug of the plate from
its slot in the outer tube end.
5. Pull the torque tube assembly and tube end
gasket out of the torque tube arm.
6. Install a new tube end gasket and insert the
torque tube assembly into the torque tube arm as
shown in figure 15. Rotate the torque tube assembly
until its socket mates with the driver member on the
displacer rod assembly and so the outer tube flange
rests against the gasket. With a thumb on the upper
portion of the positioning plate and a screwdriver in
the slots as shown in figure 15, rotate the plate and
press the lug on the plate into the hole in the torque
tube arm.
7. Install the retaining flange and secure it with four
nuts (key 18), being sure to tighten all nuts evenly.
