Emerson Fisher 249P, Fisher 249BP, Fisher 246CP Instruction Manual

Instruction Manual

D200100X012

Fisherr 249 Cageless Displacer Sensors

249 Cageless Sensors

December 2012

Contents

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

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

Description 1.................................

Type Number Description 2.....................

Educational Services 3.........................

Maintenance 3.................................

Removing the Displacer and Stem 4..............

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 9....................

Simulation of Process Conditions for
Calibration of Fisher Level Controllers

and Transmitters 10............................

Parts Ordering 10...............................

Parts Kits 11...................................

Parts List 11...................................

Sensor Common Parts 11.......................

Figure 1. Fisher 249V Sensor with FIELDVUE™
DLC3010/DLC3020f Digital Level Controller

W3120‐3

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 Process Management 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

December 2012

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.

Type Number Description

D 249BP—CL150, 300, 600 steel top‐mounted sensor

D 249CP—CL150, 300, 600 stainless steel top‐mounted sensor

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Instruction Manual

D200100X012

249 Cageless Sensors

December 2012

D 249P—CL150, 300, 600, 900 or 1500 steel top‐mounted sensor

Note

249P CL150, 300, and 600 sensors are only available in Europe.

D 249V—CL125 or 250 cast iron or CL150, 300, 600, 900, or 1500 steel side‐mounted sensor

Note

249V sensors are only available in Europe.

All cageless 249 sensors have flanged connections.

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
P.O. Box 190; 301 S. 1st Ave.
Marshalltown, IA 50158-2823
Phone: [phone] or
Phone: [phone]
FAX: [phone]
e‐mail: [e-mail]

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.

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249 Cageless Sensors

December 2012

Instruction Manual

D200100X012

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 5

D 249CP—figure 6

D 249P—figure 7

D 249V—figure 8

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.

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Instruction Manual

D200100X012

249 Cageless Sensors

December 2012

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 249V, 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).

CAUTION

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.

2. Support the sensor head (key 2) and the torque tube arm (key 3). Remove the bolting that holds the sensor head to
the process vessel.

CAUTION

When removing a sensor from a process vessel, the displacer may remain attached to the displacer rod and be lifted out
with the sensor head (key 2) when the sensor head is removed. If separating the displacer and displacer rod before
removing the sensor head, remove the cotter spring (key 11). If the displacer comes out with the head or torque tube arm,
be careful not to damage the displacer or bend the stem when setting the head or arm down.

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