Fisher 249 Series Instruction Manual

Instruction Manual
Form 1803
September 2004
Cageless 249 Series Displacer Sensors
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope of Manual . . . . . . . . . . . . . . . . . . . . . . . . . .
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Type Number Description
Educational Services
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removing the Displacer and Stem
Replacing the Displacer, Cotter Spring,
Stem End Piece, and Displacer Spud
Replacing the Displacer Rod/Driver Assembly 5
Replacing the Torque Tube
Replacing the Torque Tube Arm and
Changing the Mounting
Parts Ordering . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sensor Common Parts
Indicating Gauge . . . . . . . . . . . . . . . . . . . . . . . . .

Introduction

Scope of Manual

This instruction manual includes maintenance and
parts ordering information for the cageless 249
Series sensors.
Although a Type 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.
No person may install, operate or maintain a
cageless Type 249 Series sensor without first D
being fully trained and qualified in valve, actuator
and accessory installation, operation and
maintenance, and D carefully reading and
understanding the contents of this manual. If you
have any questions about these instructions, contact
your Fisher sales office.
www.Fisher.com
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Cageless 249 Series Sensors
1
1
1
2
2
2
3
5
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6
7
7
8
8
8
W3120-3 / IL
12
Figure 1. Type 249V Sensor with DLC3000 Series

Description

The 249 Series sensors are designed to measure
liquid level, interface level, or density/specific gravity
inside a process vessel.
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.
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
Digital Level Controller