Instruction Manual
D200099X012
249 Caged Sensors
April 2017
7
because it was in a pressurized vessel, may contain process liquid that becomes pressurized due to a change in
temperature, and may contain process liquid that is flammable, hazardous or corrosive.
WARNING
Sudden release of pressure, contact with hazardous liquid, fire, or explosion, which may result in personal injury or
property damage, can occur if a displacer that is retaining pressure or process liquid is punctured, subjected to heat, or
repaired.
Handle the displacer with care:
1. Before starting any maintenance procedure, be sure the following safety actions have been completed.
Relieve process pressure in the vessel where the 249 sensor is installed.
Drain the process liquid from the vessel.
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.
Be sure the cage is also free of process pressure and/or liquid. Use caution when loosening flange bolting or pipe
plugs.
Be sure process pressure or liquids have not penetrated the displacer.
2. Properly support the cage head or sensor head (key 2) and the torque tube arm (key 3). Remove the cap screws or
stud bolts (key 21) and hex nuts (key 22) that hold the cage head to the cage.
CAUTION
When removing the sensor from the cage, the displacer may remain attached to the displacer rod and be lifted out with the
cage head (key 2) when the cage head is removed. If separating the displacer and displacer rod/drive assembly (key 9)
before removing the cage head, remove the cotter spring (key 11).
Be careful not to let the displacer slip and drop into the bottom of the cage, as displacer damage could result.
3. When removing the sensor from the cage, the displacer may remain attached to the displacer rod and be lifted out
with the cage head (key 2) when the cage head is removed. If separating the displacer and displacer rod/driver
assembly (key 9) before removing the cage head, remove the cotter spring (key 11) according to the Replacing the
Displacer, Cotter Spring, Stem End Piece, and Displacer Spud section. Be careful not to let the displacer slip and
drop into the bottom of the cage, as displacer damage could result.
4. Carefully remove the cage head and lift out the displacer (key 10). If the displacer comes out with the cage head, be
careful not to damage the displacer or bend the stem when setting the cage head down.
5. Follow the procedure for replacing the displacer, displacer rod assembly, cotter spring, stem end piece, and
displacer spud as necessary.
Replacing the Displacer, Cotter Spring, Stem End Piece, and Displacer
Spud
The cotter spring (key 11), the ball on the displacer rod/driver assembly (key 7), and the stem end piece (key 23) or
displacer spud socket may be either too worn for a secure connection or so clogged or corroded that the displacer
does not pivot properly. Replace these parts, as necessary.
