Instruction Manual
D103288X012
Fisher™ 249VS Cageless Displacer Sensor
249VS Sensor
May 2022
Contents
Introduction 1.................................
Scope of Manual 1.............................
Description 1.................................
Educational Services 3.........................
Installation 3..................................
Mounting the Sensor on the Process Vessel 4......
Maintenance 5.................................
Removing the Displacer and Stem 6..............
Replacing the Displacer, Cotter Spring,
Stem End Piece, and Displacer Spud 8..........
Replacing the Displacer Rod/Driver Assembly 8....
Replacing the Torque Tube 9....................
Replacing the Torque Tube Arm and
Changing the Mounting Position 10............
Simulation of Process Conditions for
Calibration of Fisher Level Controllers
and Transmitters 11............................
Parts Ordering 11...............................
Parts Kits 12...................................
Parts List 12...................................
Sensor Common Parts 12.......................
Figure 1. Fisher 249VS Sensor with FIELDVUE
DLC3010/DLC3020f Digital Level Controller
W9355-1
™
Introduction
Scope of Manual
This instruction manual includes maintenance and parts ordering information for the cageless Fisher 249VS sensor.
Although a 249VS sensor is usually shipped with an attached controller or transmitter, this manual does not include
operation, installation, calibration, maintenance, or 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 249VS 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
The 249VS sensor is designed to measure liquid level, interface level, or density/specific gravity inside a process vessel.
before proceeding.
www.Fisher.com
249VS Sensor
May 2022
Instruction Manual
D103288X012
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. Side‐Mounted Cageless Wafer‐Style Sensor Assembly
TRAVEL STOP
ASSEMBLY
KNIFE EDGE BEARING
W1800‐1
DISPLACER ROD
DISPLACER
TORQUE TUBE
W9353
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 rod fits into a socket on the
outside of the welded end 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. Figure 3 shows how the controller or transmitter mounts on the torque tube
arm.
The 249VS wafer‐style sensor mates with cast iron CL125 flat face and CL250 raised face flanges, and CL150, 300, 600,
900, and 1500 raised face steel flanges. The 249VS is also available with CL600, 900, 1500, and 2500 butt weld end
process connections.
Unless otherwise noted, all NACE references are to NACE MR0175‐2002.
The Parts List section shows some standard 249VS displacer lengths. Table 1 contains displacer and torque tube
materials. However, 249VS parts are available in a wide variety of materials of construction, part dimensions, and
other specifications. Contact your Emerson sales office
for assistance in selection of specific materials, dimensions,
and specifications.
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Instruction Manual
D103288X012
Figure 3. Torque Tube Arm Exploded View Showing Controller or Transmitter Mounting
249VS Sensor
May 2022
CONTROLLER OR TRANSMITTER
(DLC3010/DLC3020f
SHOWN)
X1469
RETAINING
FLANGE
ROTARY SHAFT
POSITIONING
PLATE
MOUNTING HOLES ACCEPT
FOUR STUDS OR CAP SCREWS
DEPENDING ON CONTROLLER OR
TRANSMITTER
OUTER
TUBE END
GASKET
HEX NUTS OR CAP
SCREWS DEPENDING ON
CONTROLLER OR TRANSMITTER
TORQUE
TUBE ARM
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
Educational Services
For information on available courses for 249VS 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
Installation
WARNING
To avoid personal injury or property damage resulting from the sudden release of pressure:
D Always wear protective clothing, gloves, and eyewear when performing any installation operations.
D Check with your process or safety engineer for any additional measures that must be taken to protect against process
media.
D If installing into an existing application, also refer to the WARNING at the beginning of the Maintenance section of this
instruction manual.
3
249VS Sensor
May 2022
Instruction Manual
D103288X012
The 249VS is installed directly on the vessel as shown in figure 4. The sensor mounts on the side of the vessel using an
NPS 4 flat face or raised face flange.
Because the displacer hangs inside the vessel, provide a stillwell around the displacer if the fluid is in a state of constant
agitation to avoid excessive turbulence around the displacer. For interface or fluid level applications, install a gauge
glass on the vessel.
Figure 4. Fisher 249VS Sensor Side Mounted on Vessel
NPS 4 RF FLANGE
DISPLACER
STILLWELL
NOTE:
1STILLWELL REQUIRED AROUND DISPLACER IF THE FLUID IS IN A STATE OF
CONTINUOUS AGITATION
W9356-1
249VS
1
Mounting the Sensor on the Process Vessel
NOTICE
If inserting the displacer into the vessel before attaching it to the displacer rod, provide a means of supporting the displacer
to prevent it from dropping into the vessel and being damaged.
Install the sensor wafer body on the vessel using the following procedure.
Attach the displacer to the displacer rod (see figure 5) before installing the sensor on the vessel.
1. Place a connecting flange gasket on the sensor assembly.
2. Install four line flange studs and nuts in the connecting flange at locations that correspond to the sensor mounting
lug locations.
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Instruction Manual
D103288X012
Figure 5. Displacer and Displacer Rod Connections
COTTER SPRING
DISPLACER ROD
DISPLACER STEM
EXTENSION
LOCKING NUTS
DISPLACER SPUD
249VS Sensor
May 2022
3. Insert the displacer and the 249VS sensor into the process connection/vessel.
4. Place a blind flange on the back of the sensor and lightly secure (tightening nuts enough to hold wafer body and
gasket in place) using four line flange bolt nuts, centering the connecting flange gasket and sensor on the vessel
connecting flange.
5. Install the remaining line flange bolts and nuts.
6. Tighten all nuts in a crisscross fashion.
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 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 249VS sensor and vent any
pneumatic supply pressure.
D Use caution when loosening flange bolting.
D Remove the controller or transmitter from the torque tube arm (key 1).
Before performing any maintenance procedure requiring the handling of the displacer, inspect the displacer (key 9) 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:
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