Instruction Manual
D103288X012
249VS Sensor
July 2018
7
CAUTION
Be careful not to let the displacer slip and drop into the bottom of the process vessel, as displacer damage could result.
When removing a sensor assembly from a process vessel, the displacer may remain attached to the displacer rod and
removed with the sensor assembly.
If the displacer is removed with the sensor assembly, be careful not to damage the displacer or bend the displacer stem
when setting the sensor assembly down.
If separating the displacer and displacer stem during the removal of the sensor assembly from the process vessel, remove
the cotter spring (key 8) and separate the displacer/displacer stem from the sensor assembly.
Be careful not to let the displacer slip and drop into the bottom of the process vessel, as displacer damage could result.
1. Before starting any maintenance procedure, be sure the following safety actions are completed.
D
Relieve process pressure in the process vessel where the 249VS sensor is installed.
D
Drain the process liquid from the process vessel.
D
Shut off any electrical or pneumatic input to the controller or transmitter attached to the 249 sensor and vent
any pneumatic supply pressure. Remove the controller or transmitter from the torque tube arm.
D
Use caution when loosening flange bolting or pipe plugs.
D
Be sure process pressure or liquids have not penetrated the displacer.
2. Carefully remove the torque tube arm.
3. On the 249VS, the travel stop plate can be located in one of four positions, as shown in figure 6.
For proper operation in the target application, the displacer rod must not touch either plate over the expected
range of process conditions.
D
When the displacer is completely submerged in the upper fluid, the net load of weight minus buoyancy must be
low enough to allow the displacer rod to be above the lower plate.
D
When the displacer is completely submerged in the lower fluid, the net load of weight minus buoyance must be
high enough to keep the displacer rod from hitting the upper plate.
If necessary, remove the place and choose a position where the rod will not touch the plate.
4. Follow the procedure for replacing the displacer, displacer rod assembly, cotter spring, stem end piece, and
displacer spud as necessary.
Figure 6. Fisher 249VS Travel Stop Plate Positions
BJ8646‐A
1
HIGH
2
INTERMEDIATE
3
INTERMEDIATE
4
LOW
