Instruction Manual
D200100X012
Fisher™ 249 Cageless Displacer Sensors
249 Cageless Sensors
May 2022
Contents
Introduction 1.................................
Scope of Manual 1.............................
Description 1.................................
Type Number Description 3.....................
Hazardous Area Classification 3..................
Educational Services 3.........................
Maintenance 4.................................
Removing the Displacer and Stem 5..............
Replacing the Displacer, Cotter Spring,
Stem End Piece, and Displacer Spud 6..........
Replacing the Displacer Rod/Driver Assembly 7....
Replacing the Torque Tube 8....................
Replacing the Torque Tube Arm and
Changing the Mounting 10...................
Simulation of Process Conditions for
Calibration of Fisher Level Controllers
and Transmitters 10............................
Parts Ordering 11...............................
Parts Kits 11...................................
Parts List 11...................................
Sensor Common Parts 11.......................
Figure 1. Fisher 249BP Sensor with FIELDVUE
DLC3010/DLC3020f Digital Level Controller
X1471
™
Introduction
Scope of Manual
This instruction manual includes maintenance and parts ordering information for Fisher 249 cageless displacer
sensors.
Although a 249 sensor is usually shipped with attached controller or transmitter, this manual does not include
operation, installation, calibration, maintenance, and parts ordering information for the controller/transmitter or for
the complete unit. For this information, refer to the appropriate controller/ transmitter instruction manual.
Do not install, operate, or maintain a 249 sensor without being fully trained and qualified in valve,
actuator, and accessory installation, operation, and maintenance. To avoid personal injury or property
damage, it is important to carefully read, understand, and follow all of the contents of this manual,
including all safety cautions and warnings. If you have any questions about these instructions, contact
your Emerson sales office
Description
249 sensors are designed to measure liquid level, interface level, or density/specific gravity inside a process vessel.
.
www.Fisher.com
249 Cageless Sensors
May 2022
Instruction Manual
D200100X012
A torque tube assembly (figure 2) and displacer provide an indication of liquid level, interface level, or density/specific
gravity. The torque tube assembly consists of a hollow torque tube with a shaft welded inside it at one end and
protruding from it at the other end.
Figure 2. Typical Side‐Mounted Cageless Displacer
TRAVEL STOP ASSEMBLY
W1800‐1
DISPLACER ROD
DISPLACER
TORQUE TUBE
W0172‐1
KNIFE EDGE BEARING
The unconnected end of the tube is sealed by a gasket and clamped rigidly to the torque tube arm, permitting the
protruding end of the shaft to twist and therefore transmit rotary motion. This allows the interior of the torque tube to
remain at atmospheric pressure, thus eliminating packing and the disadvantages of packing friction.
The displacer always exerts a downward force on one end of the displacer rod. The other end of the displacer rod rests
on the knife‐edge of the driver bearing. A keyed shaft on the bearing end of the displacer fits into a socket on the
outside of the welded end of the of the torque tube assembly.
A change in liquid level, interface level, or density/specific gravity buoys up the displacer by a force equal to the weight
of the liquid displaced. Corresponding vertical movement of the displacer results in angular movement of the displacer
rod around the knife edge. Since the torque tube assembly is a torsional spring which supports the displacer and
determines the amount of movement of the displacer rod for a given displacement change, it will twist a specific
amount for each increment of buoyancy change. This rotation is brought through the torque tube arm by the
protruding rotary shaft. A controller or transmitter attached to the end of the rotary shaft converts the rotary motion
into varying pneumatic or electric signals.
Unless otherwise noted, all NACE references are to NACE MR0175-2002.
2
Instruction Manual
D200100X012
249 Cageless Sensors
May 2022
Type Number Description
D 249BP—CL150, 300, 600 WCC (steel) top‐mounted sensor
D 249CP—CL150, 300, 600 stainless steel top‐mounted sensor
D 249P—CL150, 300, 600, 900 or 1500 steel top‐mounted sensor
Note
249P CL150, 300, and 600 sensors are only available in Europe.
All cageless 249 sensors have flanged connections.
The Parts List section shows some 249 sizes by construction and standard displacer lengths and table 1 contains
displacer and torque tube materials. However, 249 parts are available in a wide variety of materials of construction,
part dimensions, and other specifications. Contact your Emerson sales office
materials, dimensions, and specifications.
for assistance in selection of specific
Table 1. Displacer and Torque Tube Materials
Part Standard Material Other Materials
Displacer 304 Stainless Steel 316 Stainless Steel, N10276, N04400, Plastic, and Special Alloys
Displacer Stem, Driver Bearing,
Displacer Rod and Driver
Torque Tube N05500
1. N05500 is not recommended for spring applications above 232_C (450_F). Contact your Emerson sales office or application engineer if temperatures exceeding
this limit are required.
316 Stainless Steel N10276, N04400, other Austenitic Stainless Steels, and Special Alloys
(1)
316 Stainless Steel, N06600, N10276
Hazardous Area Classification
Complies with the requirements of ATEX group II Category 2 Gas and Dust
Ex h IIC Tx Gb
Ex h IIIC Tx Db
Maximum surface temperature (Tx) depends on operating conditions.
Gas: T6...T2
Dust: T85...T232
Educational Services
For information on available courses for 249 displacer sensors, as well as a variety of other products, contact:
Emerson Automation Solutions
Educational Services - Registration
Phone: 1-641-754-3771 or 1-800-338-8158
E-mail: education@emerson.com
emerson.com/Fishervalvetraining
3
249 Cageless Sensors
May 2022
Instruction Manual
D200100X012
Maintenance
Sensor parts are subject to normal wear and must be inspected regularly and replaced as necessary. The frequency of
inspection and replacement depends upon the severity of service conditions.
WARNING
Always wear protective clothing, gloves, and eyewear when performing any maintenance operations to avoid personal
injury.
Avoid personal injury or property damage resulting from the sudden release of pressure. Before performing any
maintenance procedure:
D Relieve any process pressure in the process vessel where the 249 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.
D Use caution when loosening flange bolting or pipe plugs (key 26).
D Remove the controller or transmitter from the torque tube arm (key 3).
Before performing any maintenance procedure requiring the handling of the displacer, inspect the displacer (key 10) to
make sure process pressure or liquids have not penetrated the displacer.
The displacer in this unit is a sealed container. If penetrated by process pressure or liquid, the displacer may hold pressure
or hazardous liquid for an extended period. A displacer that has been penetrated by process pressure or liquid may contain:
D pressure as a result of being in a pressurized vessel.
D liquid that becomes pressurized due to a change in temperature.
D liquid that is flammable, hazardous, or corrosive.
Sudden release of pressure, contact with hazardous liquid, fire, or explosion, which might 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. Consider the characteristics of the specific process liquid in use.
Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.
Note
Except for gaskets (keys 13, 14), trouble symptoms peculiar to specific parts are discussed in the following sections. Each section is
specific to these parts. Regardless of location, gasket failure is indicated by leakage in the gasket area. Every time a gasket is
removed, replace it with a new one upon reassembly.
The procedures below apply to all sensor types except where indicated. Key numbers used are shown in the following
illustrations:
D 249BP—figure 4
D 249CP—figure 5
D 249P—figure 6
4
Instruction Manual
D200100X012
249 Cageless Sensors
May 2022
Removing the Displacer and Stem
The displacer (key 10) is a sealed container. If the displacer has been penetrated by process pressure or liquid, it may
hold pressure or hazardous liquid for an extended period.
Process residue buildup on the displacer and stem (key 24) may change displacer weight or displacement. A bent stem
or a dented or corroded displacer can impair performance.
If the displacer rests against the travel stop, appears to be overweight, or causes output drift or other output
inaccuracies, it may have been penetrated by process pressure or liquid. Such a displacer may contain pressure
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.
Note
On the 249P and 249BP with travel stop, the displacer must come out with the sensor head (key 2) or torque tube arm
(key 3) before being completely disconnected from the displacer rod (key 7). If separating the displacer and displacer rod, remove
the cotter spring (key 11).
NOTICE
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 249 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.
5
Loading...