Emerson Fisher 249, Fisher 249B, Fisher 249BF, Fisher 249C, Fisher 249K Instruction Manual

Instruction Manual

D200099X012

Fisherr 249 Caged Displacer Sensors

249 Caged Sensors

August 2014

Contents

Introduction 1.................................

Scope of Manual 1.............................

Description 2.................................

Type Number Description 3.....................

Educational Services 4.........................

Maintenance 4.................................

Cleaning the Cage 5...........................

Removing the Displacer and Stem 6..............

Replacing the Displacer, Cotter Spring, Stem

End Piece, and Displacer Spud 7...............

Replacing the Displacer Rod/Driver Assembly 8....

Replacing the Torque Tube 9....................

Changing Cage Head Position 10................

Replacing the Torque Tube Arm and

Changing the Mounting 11...................

Simulation of Process Conditions for Calibration

 of Fisher Level Controllers and Transmitters 12....

Related Documents 12..........................

Parts Ordering 12...............................

Parts Kits 13...................................

Parts List 13...................................

Figure 1. Fisher 249B Sensor with 2500 Controller

W3121‐3

Introduction

Scope of Manual

This instruction manual includes maintenance and parts ordering information for 249 caged 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.

Note

Caged sensors have a rod and block shipping lock installed on each end of the displacer to protect the displacer in shipping, as
shown in figure 2. Remove these parts before installing the sensor to allow the displacer to function properly.

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

www.Fisher.com

249 Caged Sensors

August 2014

Instruction Manual

D200099X012

carefully read, understand and follow all the contents of this manual, including all safety cautions and warnings. If you
have any questions about these instructions, contact your Emerson Process Management sales office before
proceeding.

Description

249 sensors are designed to measure liquid level, interface level, or density/specific gravity inside a vessel.

A torque tube assembly (figure 3) 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. Rod and Block Shipping Lock

SHIPPING BLOCK

LOCK NUT

SHIPPING STOP ROD

X1114

Figure 3. Typical Caged Displacer

W1800-1

KNIFE EDGE
BEARING

ROTATABLE
HEAD

TORQUE TUBE

DISPLACER ROD

DISPLACER

CAGE

SHIPPING STOP ROD

X1113

LOCK NUT

2

SHIPPING BLOCK

W2141-1

Instruction Manual

D200099X012

249 Caged Sensors

August 2014

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 4 shows how the controller or transmitter mounts on the torque tube
arm.

Unless otherwise noted, all NACE references are to NACE MR0175-2002.

Figure 4. Torque Tube Arm Exploded View Showing Controller or Transmitter Mounting

CONTROLLER OR TRANSMITTER
(DLC3010/DLC3020f
SHOWN)

GE51212

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

Type Number Description

 249—CL125 or 250 cast iron cage with screwed or flanged connections.

 249B—CL150, 300, or 600 steel cage with screwed or flanged connections.

 249BF—CL150, 300, or 600 cast steel or stainless steel cage with flanged connections only. Available from Emerson

Process Management in Europe only.

 249C—CL150, 300, or 600 stainless steel cage with screwed or flanged connections.

 249K—CL900 or 1500 steel cage with flanged connections only.

 249L—CL2500 steel cage with flanged connections only.

The cage head on all of the 249 constructions may be rotated to any of the eight alternate positions shown in figure 7.
Connection sizes are either NPS 1‐1/2 or 2.

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249 Caged Sensors

August 2014

Instruction Manual

D200099X012

The Parts List section shows some 249 sizes by construction, standard displacer lengths, and standard materials 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 Process Management sales office for
assistance in selection of specific materials, dimensions, and specifications.

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 Process Management 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 249 displacer sensors, as well as a variety of other products, contact:

Emerson Process Management
Educational Services, Registration
Phone: [phone] or [phone]
e‐mail: [e-mail]
http://www.emersonprocess.com/education

Maintenance

Sensor parts are subject to normal wear and must be inspected 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 installation operations to avoid personal
injury.

Avoid personal injury or property damage resulting from the sudden release of pressure. Before performing any
maintenance procedure:

 Relieve any 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.

 Use caution when loosening flange bolting (key 22) or pipe plugs (key 17, 26, or 27).

 Remove the controller or transmitter from the torque tube arm (key 3).

Before continuing with any maintenance procedure, be sure the cage (key 1) is also free of process pressure and/or liquid.
Use caution when loosening flange bolting (key 22) or pipe plugs (key 17, 26, or 27).

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.

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Instruction Manual

D200099X012

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:

 pressure as a result of being in a pressurized vessel

 liquid that becomes pressurized due to a change in temperature

 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 and 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.

249 Caged Sensors

August 2014

The procedures below apply to all sensor types except where indicated. Key numbers used are shown in the following
illustrations:

249—figure 8

249B—figure 9

249C—figure 10

249K—figure 11

249L—figure 12

Cleaning the Cage

Process residue buildup in the bottom of the cage (key 1) or at the connections may restrict flow in and out of the cage
or interfere with displacer motion. Remove the cage to clean out process residue buildup.

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 (key 3). Take
care not to damage the torque tube assembly (key 9) inside the torque tube arm.

 Be sure the cage is also free of process pressure and/or liquid. Use caution when loosening flange bolting (key 22)

or pipe plugs (keys 17, 26, or 27).

 Be sure process pressure or liquids have not penetrated the displacer (key 10).

2. Properly support the cage head (key 2) and the torque tube arm. Remove the cap screws or stud bolts (key 21) and
hex nuts (key 22) that hold the cage head to the cage.

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249 Caged Sensors

August 2014

Instruction Manual

D200099X012

CAUTION

When removing a sensor from a cage, the displacer may remain attached to the displacer rod and be lifted out with the
cage head when the cage head is removed. If separating the displacer and displacer rod 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. Carefully remove the cage head and lift out the displacer.

4. A style 1 or 4 (screwed or flanged) cage must be disconnected at the lower connection and the liquid damper
(key 29) removed. Remove the damper by prying it out of a flanged connection or by unscrewing it from a screwed
connection with a 1/2‐inch hex (Allen) wrench. If necessary, completely remove the style 4 cage from the vessel.

5. For complete drainage and cleaning of a cage with style 2 or 3 (screwed or flanged) connections (figure 5), remove
the pipe plug (keys 17 or 26) from the bottom of the cage. Remove the liquid damper (key 29). If necessary,
completely remove the cage from the vessel.

Figure 5. Cage Connection Styles

STYLE 1: TOP
AND BOTTOM

SCREWED: S1
FLANGED: F1

A1271-2

STYLE 2: TOP
AND LOWER SIDE

SCREWED: S2
FLANGED: F2

STYLE 3: UPPER
AND LOWER SIDE

SCREWED: S3
FLANGED: F3

STYLE 4: UPPER
SIDE AND BOTTOM

SCREWED: S4
FLANGED: F4

6. Use appropriate cleaning techniques, tools, and solutions. After cleaning the cage, install the liquid damper and
reconnect the cage to the vessel. Install the cage head and controller/transmitter. Properly calibrate the
controller/transmitter following the procedures given in the controller/transmitter instruction manual.

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

6