Instruction Manual
D103288X012
249VS Sensor
July 2018
10
CAUTION
Support the sensor assembly to avoid damage to the displacer, displacer stem, displacer rod assembly, and associated
parts.
1. After following the proper procedure to remove the sensor assembly from the process vessel, move the sensor
assembly to a suitable maintenance area.
2. Remove the controller/transmitter and displacer (key 9).
3. Remove the nuts (key 13) and retaining flange (key 12) holding the positioning plate (key 21) 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 would cause damage.
4. Remove the positioning plate (key 21) by freeing its two lugs.
The vertical lug fits into a hole in the flange of the torque tube arm (top of figure 7). The horizontal lug (hidden
behind the screwdriver at the bottom of figure 7) fits into a slot in the outer tube end of the torque tube assembly
(the figure 7 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 7. 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. Remove the tube end gasket
(key 17) and discard (a new gasket will be installed in step 6). Clean and inspect the gasket mating surfaces.
6. Install a new tube end gasket into recess in torque tube arm.
7. Insert the torque tube assembly into the torque tube arm as shown in figure 7. 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 7, rotate the plate and press the lug on the plate into the hole in the torque tube arm (this will
preload the torque tube).
8. Install the retaining flange and secure it with four nuts (key 13), being sure to tighten all nuts evenly.
9. Install the sensor head and controller/transmitter. Calibrate the controller/transmitter following the procedures
given in the controller/transmitter instruction manual.
Replacing the Torque Tube Arm and Changing the Mounting Position
Looseness of the driver bearing (key 3), wear on its knife‐edged surface, or a bent, worn, or corroded displacer rod
assembly (key 14) may impair performance. Be especially sure to check the ball on the displacer rod.
CAUTION
Support the sensor assembly to avoid damage to the displacer, displacer stem, displacer rod assembly, and associated
parts.
